IES - Objective Paper I II El

I.E.S-(OBJ) 1997

1 of 16

ELECTRICAL ENGINEERING PAPER-I 1.

The electric field Eat any point Z is given by

A charge distribution is shown in the given figure:

r ρ a. E = ∈0 r ρ b. E = ∈0 r ρ c. E = ∈0 r ρ E= ∈0

Which of the following expressions for the displacement flux density D due to the given charge distribution is correct? 1. D = − ρ 0 aix for x < − a 2. D = − ρ 0 ( x + a ) ix for − a < x < 0 3. D = + ρ 0 ( x − a ) ix for 0 < x < a

2.

4. D = + ρ0 aix for x > a Select the correct answer using the codes given below: a. 1 and 4 b. 2 and 3 c. 1,2 and 3 d. 2,3 and 4 Two concentric metallic spheres of radii ‘a and ‘b’ carry charges + Q and – Q respectively as shown in the given figure. Potential at the centre ‘P will be

a. Zero Q b. 4π ∈0 b −Q c. 4π ∈0 a Q ⎛1 1⎞ ⎜ − ⎟ 4π ∈0 ⎝ a b ⎠ An infinite plane surface carries a uniform charge density p/m2 as shown in the figure.

d. 3.

d.

=−

Z r az |Z | Z r az Z > 0 = 0, Z = 0 |Z | Z r az | Z |> 0 = 0, Z = 0 |Z| |Z | r az , Z < 0 Z

ρ |Z| r

∈0 Z

az , Z < 0

= 0, Z = 0 4.

5.

A magnetic field B and an electric field E are at right angles to each other along the y-axis and x = axis respectively as shown in the given figure. the path of an electron which starts at the origin will be

a. Straight along the y-axis b. Cycloidal along the x-axis c. Straight along the z-axis d. Cycloidal along the z-axis An infinitely long conductor carrying a current I in a region permeability μ 1 and in the vicinity of another region of permeability μ 1 is shown in the given figure for calculating the field in the first region, the effect of discontinuity is replaced by an image I’ and with μ 1 < μ2

which one of the following statements is correct in this regard?

6.

7.

8.

a. I and I’ have the same strength and direction b. I and I’ have opposite direction but the same strength c. 1 and I’ have the same direction but different strength d. I and I’ have opposite direction and different strength The image of the dipole of moment P in the grounded sphere shown in the given figure is

a. A dipole of moment P b. A dipole of moment PR/d c. A dipole of moment PR2/d2 d. Not a dipole If two concentric square loops A and B shown in the given figure carry equal currents in the same sense, then the magnetic field at ‘O due to the two loops A and B will be in the ratio

a. 1: 2 b. 1 : 1 c. 2 :1 d. 2 : 1 Match List-I (Phenomena) with List-Il (Reasons) and select the correct answer using the codes given below the lists: List I A. Force on a unit north pole due to current B. Flux density intensity relation in a magnetic material C. Force of attraction between a current carrying conductor and a magnetic slab

9.

10.

11.

12.

2 of 16 D. Identically zero magnetic field outside a coaxial cable List II 1. Magnetic Polarization 2. Maximization of magnetic lines of force 3. Work done along a closed path is equal to total current flow 4. Force between magnetic elements A B C D 3 1 2 4 a. b. 4 1 2 3 3 2 1 4 c. 4 2 1 3 d. Two point charges Q and – Q are located on the surface of a sphere of radius R as shown in the figure. The average electric field in the volume of the sphere is

a. Infinite r 2Q −n ) b. 2 ( 4π ∈0 R r 2Q c. +n ) 2 ( 4π ∈0 R d. Zero A flat slab of, dielectric ( ∈r = 5 )is placed normal to a uniform field with a flux density D = 1 Coulomb/m2. The slab is uniformly polarized. Polarization V in the slab (in Coulomb/m2) will be a. 0.8 b. 1.2 c. 4.0 d. 6.0 A parallel plate capacitor with air as dielectric is charged and then disconnected from the supply. The force between the plates is F. If the cap actor is now immersed in a liquid dielectric of dielectric constant e, then the force between the plates will be a. ∈2 F b. ∈ F c. F d. F / ∈ Match List-I with List-II and select the correct answer using the codes given below the Lists: (Symbols have the usual meanings)

List I A. Poisson’s equation B. Laplace’s equation C. Joule’s equation D. Helmholtz’s equation List II 1. ∇ 2φ = 0

17.

2. ∇ 2 E + K 02 E = 0 where K 0 = ω μ0 ∈0

3. ∇ φ = − 2

ρ

a.

∈0

dP = U j = E. J dV A B C D a. 2 1 4 3 3 4 1 2 b. 3 1 4 2 c. d. 2 4 1 3 A circular loop has its radius increasing at a rate of 2m/s. The loop is placed perpendicular to a constant magnetic field of 0.1 Wb/m2. When the radius of the loop is 2 m, the emf induced in the loop will be a. 0.8π V b. 0.4π V c. 0.2π V d. Zero Kirchhoff’s current law for direct currents is implicit in the expression r a. V .D = ρ r b. ∫ J .n ds = 0 r c. V .B = 0 ∂D d. ∇ × H = J + ∂t A rectangular loop in the x-z plane bounded by the lines x = 0, x = a, z = 0 and z = b, is in a time-varying magnetic field given by B = B0 cos ωt a y

4.

13.

14.

15.

16.

Where B0 is a constant, ω is the angular frequency and ay is the unit vector in the y– direction, the emf induced in the loop is given by a. abB0 cos ωt b. abB0ω sin ωt c. B0 ω sin ωt d. Zero In a broadside array, the maximum radiation a. Occurs at 90° to the line of the array b. Occurs at 450 to the line of the array

3 of 16 c. Occurs along the line of the array d. Could occurat any angle to the line of the array At a certain frequency ‘f’ a uniform plane wave is found to have established a wavelength λ in a good conductor. Of the source frequency is doubled, then the wavelength would change to

18.

19.

20.

21.

λ

2 2λ

b. c. 2λ d. 4λ Two loss-less transmission lines 1 and .2 shown in the given figure have each a characteristic impendence Z. Line 1 is charged to a voltage of V and line 2 to a voltage of 2 V. Then both of them are discharged through resistances Z as shown. If line 1 gets fully discharged in time T, then line 2 will fully discharged in time

a. T/4 b. T/2 c. T d. 2T As the temperature of a ‘p’ type semiconductor is gradually and continuously increased, the Fermi level will move a. Into the valence band b. Into the conduction band c. Towards the middle of the forbidden gap d. Into the region between the acceptor. level and the valence band Which one of the following polarization mechanisms/ sets of mechanisms contribute (s) to the static dielectric constant of a homopolar neutral dielectric? a. Electronic b. Electronic and ionic c. Electronic, ionic and dipolar d. Electronic, and dipolar Consider the following materials: 1. Pure silica 2. Bakelite 3. Hard rubber 4. Paraffin

22.

23.

24.

25.

26.

The correct sequence of the DECREASING order of loss angle (60 Hz) these dielectric materials is a. 1, 2, 3, 4 b. 1, 4, 3, 2 c. 4, 1, 2, 3 d. 4, 3, 1, 2 Which one of the following materials is piezoelectric? a. Pb2Au b. Ba Ti O3 c. Mg A12O4 d. Ni Fe2O4 The residual resistivity of metals essentially independent of a. Is temperature b. Increase linearly with increasing temperature c. Decrease linearly with increasing temperature d. Initially increases linearly with temperature and then remains constant. Consider the following metals: 1. Zinc. 2. Gold. 3. Silver. 4. Copper. The correct sequence of the increasing order of their resistivities is a. 4, 3, 1, 2 b. 3, 4, 2, 1, c. 4, 3, 2, 1 d. 3, 4, 1, 2 Match List-I with List-II and select the correct answer: List I (Class of material) A. Ferromagnetio B. Superconductor C. Semiconductor D. Piezoelectric List II (Material) 1. YBa2 Cu2 O7 2. LiNbO3 3. Co 4. InGaAsP A B C D a. 3 1 2 4 3 1 4 2 b. c. 1 3 2 4 1 3 4 2 d. A type I superconductor maintained at a temperature T 5 d. 3 < T < 5 The Nyquist plot of the open-loop transfer function G (s) H(s) is shown in the given figure. It indicates that

93.

94.

95.

a. The open-loop system is unstable but the closed-loop system is stable b. Both open-loop and closed-loop systems are unstable c. Open-loop system is stable but closedloop system is unstable d. Both open-loop and closed-loop systems are stable In the control system shown in the given figure, the controller which can give zero steady-state error to a ramp input. with K = 9 is

a. Proportional type b. Integral type c. Derivative type d. Proportional plus derivative type The garn cross-over frequency and bandwidth of a control system are ωcu and ωbu respectively. A phase-lag network is employed for compensating the system. If the gain cross-over frequency and bandwidth of the compensated system are ωcc and ωbc respectively, then a. ωcc < ωcu ; ωbc < ωbu b. ωcc > ωcu ; ωbc < ωbu c. ωcc < ωcu ; ωbc > ωbu d. ωcc > ωcu ; ωbc > ωbu The transfer function of a certain system is Y (s) 1 = 4 3 U ( s ) s + 5s + 7 s 2 + 6 s + 3 The A, B matrix pair of the equivalent state-space model will be ⎡ 0 1 0 0 ⎤ ⎡0 ⎤ ⎢ 0 0 1 0 ⎥ ⎢0 ⎥ ⎥⎢ ⎥ a. ⎢ ⎢ 0 0 0 1 ⎥ ⎢0 ⎥ ⎢ ⎥⎢ ⎥ ⎣ −3 −6 −7 −5⎦ ⎣1 ⎦

96.

97.

98.

13 of 16 ⎡ 0 1 0 0 ⎤ ⎡0 ⎤ ⎢ 0 0 1 0 ⎥ ⎢0 ⎥ ⎥⎢ ⎥ b. ⎢ ⎢ 0 0 0 1 ⎥ ⎢0 ⎥ ⎢ ⎥⎢ ⎥ ⎣ −3 −5 −6 −7 ⎦ ⎣1 ⎦ ⎡ 0 1 0 0 ⎤ ⎡1 ⎤ ⎢ 0 0 1 0 ⎥ ⎢0 ⎥ ⎥⎢ ⎥ c. ⎢ ⎢ 0 0 0 1 ⎥ ⎢0 ⎥ ⎢ ⎥⎢ ⎥ ⎣ −5 −7 −6 −3⎦ ⎣0 ⎦ ⎡ 1 0 0 0 ⎤ ⎡0 ⎤ ⎢ 0 0 0 0 ⎥ ⎢0 ⎥ ⎥⎢ ⎥ d. ⎢ ⎢ 0 0 1 0 ⎥ ⎢0 ⎥ ⎢ ⎥⎢ ⎥ ⎣ −3 −6 −7 −5⎦ ⎣1 ⎦ A liner system is described by the state equations ⎡ x1 ⎤ ⎡1 0 ⎤ ⎡ x1 ⎤ ⎡ 0 ⎤ ⎢ ⎥=⎢ ⎥ ⎢ ⎥ + ⎢ ⎥ r C = x2 ⎣ x2 ⎦ ⎣1 1 ⎦ ⎣ x2 ⎦ ⎣1 ⎦ where r and c are the input and output reactively. The transfer function is: a. 1/ (s+1) b. 1/(5+1)2 c. 1/ (s-1) d. 1/ (s-1)2 The state equation of a dynamic system is given by X ( t ) = AX ( t )

⎡ −1 1 0 0 0 ⎤ ⎢ 0 −1 1 0 0 ⎥ ⎢ ⎥ A = ⎢ 0 0 −1 0 0 ⎥ ⎢ ⎥ ⎢ 0 0 −6 −3 4 ⎥ ⎢⎣ 0 0 0 −4 −3⎥⎦ The eigenvalues of the system would be a. Real non-repeated only b. Real non-repeated and complex c. Real repeated d. Real repeated and complex A simple electric water heater is shown in the given figure. The system can be modelled by

a. b. c. d.

A first order differential equation A second order differential equation A third order differential equation An algebraic equation

99.

Match List-I with List-Il and select the correct answer List I (Properties of frictional force) A.

102.

B.

C. 103.

100.

101.

List II (Frictional force) 1. Coulomb friction 2. Viscous friction 3. Static friction A B C a. 1 2 3 b. 2 1 3 c. 3 2 1 d. 2 3 1 Laplace transform of the output response of a liner system is the system transfer function when the input is a. A step signal b. A ramp signal c. An impulse signal d. A sinusoidal signal Match List-I with list-II and select the correct answer: List I A. Hydraulic actuator B. Flapper valve C. Potentiometer error detector D. Dumb-bell rotor List II 1. Linear device 2. A.C. servo systems 3. Large power to weight ratio 4. Pneumatic systems A B C D 4 3 2 1 a. b. 3 4 2 1 c. 3 4 1 2 d. 4 3 1 2

104.

105.

14 of 16 Which of the following statements regarding an ac servo system employing a synchro error detector are correct? 1. Sensitivity of the error detector is measured in volts/degree. 2. The transfer function of the synchro E error detector is where E = θ r − θc error voltage, θ r and θ c are reference and controlled shaft positions. 3. Sensitivity of the error detector has the same sign at the two null positions. a. 1, 2 and 3 b. 1 and 2 c. 2 and 3 d. 1 and 3 Four speed-torque curves (labelled I, II, III and IV) are shown in the given figure. That of an ac servomotor will be as in the curve labelled

a. b. c. d. A

I II III IV non-linear control system is described d 2x by the equation 2 + sin x = 0 dt dx = The type of singularity at x = π and dt 0 is: a. Centre b. Stable focus c. Saddle point d. Stable node Which one of the following pairs of phaseplane diagram and types of singularities is NOT correctly matched? Phase-plane diagram Singularity a.

b.

c.

110. d.

106.

107.

108.

109.

Consider the following state equations for a discrete system: ⎡ 1 ⎤ 0 ⎥ − ⎡ x1 ( k + 1) ⎤ ⎢ 2 ⎡ x1 ( k ) ⎤ ⎡1⎤ ⎥⎢ ⎢ ⎥=⎢ ⎥ + ⎢ ⎥ u (k ) ⎣ x2 ( k + 1) ⎦ ⎢ − 1 − 1 ⎥ ⎣ x2 ( k ) ⎦ ⎣1⎦ 4 ⎦⎥ ⎣⎢ 4 ⎡ x ( k )⎤ y ( k ) = [1 − 1] ⎢ 1 ⎥ − 4u ( k ) x k ( ) 2 ⎣ ⎦ The system given above is a. Controllable and observable b. Uncontrollable and unobservable c. Uncontrollable and observable d. Controllable and unobservable Which one of the following systems is open-loop? a. The respiratory system of man b. A system for controlling the movement of the slide of a copying milling machine c. A thermostatic control d. Traffic light control Assertion A: In general, circulation of the magnetic field intensity is zero. Reason R: Vector source of circulation is the current density. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: In some semiconductors, the Hall coefficient is positive.

111.

112.

113.

15 of 16 Reason R: In these semiconductors, the mobility of holes is greater than that of electrons. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: Intrinsic germanium does not show n-type behavior. Reason R: In intrinsic germanium, the number of electrons is less than the number of holes. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: Quartz crystal is preferred over Rochelle salt crystal for commercial piezoelectric applications. Reason R: Rochelle salt is mechanically weaker. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true A voltmeter with a resistance of 10 kΩ is connected with two other 10kΩ resistors across a 200 V 3 - phase mains, as shown in the figure:

Assertion A: The voltmeter reading will be 115 V. Reason R: The connections are similar to Scott connection. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: The bridge shown in the figure is balanced by first adjusting R1 for inductive balance and then adjusting R3 for

resistive balance; and this is repeated till balance is achieved. 117.

114.

115.

116.

Reason R: For medium-Q coils, the resistance effect is not pronounced and balance ia reached after a few adjustments. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: Electrometers are used at the output stage of electrode pH meters. Reason R: In electrode type pH meters, the potential is measured using reference and measuring electrodes. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: The frequency response shown in the given figure is that of a vibration galvanometer.

Reason R: A vibration galvanometer is the most suitable detector in ac potentiometer method of measurement. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true 1 Assertion A: The solution of 3 digit 2 voltmeter is 0.001. 1 Reason R: Addition of digit to a digital 2 voltmeter increases the range of the meter. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A

118.

119.

120.

16 of 16 c. A is true but R is false d. A is false but R is true Assertion A: Section AB on the negative real axis in the given figure lies on the root-locus.

Reason R: All the points in between A and B have two poles to the right of the points. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: Feedback control systems are often compensated by phase lead/phase-lag networks Reason R: Phase-lead/phase-lag networks are easily realizable and obtainable. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: A discrete data system having the characteristic equation 2 Z − 1.5Z − 1 = 0 is unstable. Reason R: The negative coefficients of the characteristic equation in the z-plane represent an unstable discrete system. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: A dipole placed in a uniform field experiences a torque tending to align the dipole axis with the field. Reason R: A dipole placed in a uniform field does not experience a translational force. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true

I.E.S-(OBJ) 1998

1 of 15

ELECTRICAL ENGINEERING PAPER-I 1.

2.

Consider the following statements : In electrostatics, the Equipotential surface is defined as the surface where 1. electric field intensity is normal everywhere. 2. electric field intensity is tangential everywhere. 3. no work is done in moving a charge over it. 4. no charge is present. Of these statements a. 1 alone is correct b. 3 and 4 are correct c. 1 and 3 are correct d. 2 and 4 are correct A capacitor is made up of two concentric spherical shells. The radii of the inner and outer shells are R1 and R2 respectively and ∈ is the permittivity of the medium between the shells. The capacitance of the capacitor is given by 1 ⎛1 1 ⎞ a. ⎜ − ⎟ 4π ∈ ⎝ R1 R2 ⎠

1 ⎛1 1 ⎞ ⎜ + ⎟ 4π ∈ ⎝ R1 R2 ⎠ RR c. 4π ∈ 1 2 R1 − R2 RR d. 4π ∈ 1 2 R1 − R2 A charge + q is placed at the centre of a spherical cavity in a grounded conduting sphere as shown in the figure. Another charge +Q is placed outside on the line joining O and O’. The force acting on the charge + q will be

4.

5.

b.

3.

a.

pQ 4π ∈0 ( D + d )

pQ 4π ∈0 D c. zero d. dependent on the charge density distribution on the conductor and will not have a closed-form expression. Two point charges (Q1 = Q, Q2 = 2Q) and an infinite grounded plane are shown in the figure. The forces F1 and F2, on Q1 and Q2, will be in the ratio b.

6.

a. 1 : 1 b. 1 : 2 c. 1 : 4 d. 1 : 8 Two rectangular loops and an infinite wire, all carrying current ‘I’ are shown in the given figure. If the force on loop I due to the infinite wire were ‘F’, then the force on loop 2 due to the infinite wire would be

a. F/3 b. F/2 c. F 3 d. F 2 An infinite number of concentric circular loops carry a current ‘I’ each hut alternately in opposite directions. The radii of the loops are R, 2R, 4R………. in geometric progression. The magnetic flux density at the centre of the loops will be a. Zero μ0 I b. 3R

c.

7.

2 of 15

μ0 I

4R μ0 I d. 6R For a current element IdI. situated at an arbitrary point, the magnetic vector potential A equals (R is the distance, of the observation point from the centre of the current clement) a. μ IdI / (4π R)

a. e = − ∫

8.

9.

a. f = b. f =

σ2 2 ∈0

σ2 ∈0

c. d. 12.

11.

c

An infinite dielectric slab is uniformly polarized as shown in the figure. The electric field inside the slab given by

2P n ∈0 2P −n b. ∈0 P n c. ∈0 P d. −n ∈0 Match List-I with List-Il and select the correct answer using the codes given below the lists : List-I A. ∇.D = ρ ∂ρ B. ∇.J = ∂t C. ∇ × H = jc

{ }

()

( )

13.

a0

c. f =∈0 σ 2 a 0 10.

c

a.

a0

d. f = 0 Two conducting shells of radii r1 and r, (r1 > r2), each with a charge ‘Q’ are placed far apart in uniform external electric field. The space surrounding each shell is filled with the same dielectric material. In this situation, the a. shells will not experience any force b. shells will experience identical force c. shell with radius r1 will experience a greater force d. shell with radius r2 will experience a greater force When a closed conducting loop ‘C’ is moving with a constant velocity ‘V’ through a non-uniform time-varying magnetic field ‘B’, the voltage induced in the loop is given by

( ) e = −φ ( B × V ) .d I ∂B e = −∫ d s + φ (V − B ) d I ∂t

b. e = −φc V × B .d I

b. μ IdI / (4π R 2 ) c. μ IdI / (4π R ) d. μ IdI / (2π R) Tangential component of the electric field on a perfect conductor will be a. infinite b. zero c. same as the normal field component and 90° out of phase d. same as the normal component but 1800 out of phase The force f per unit area On the surface of conductor, with surface charge density σ. in the presence of an electric field is (an is unit outward normal to the conductor surface)

∂B ds ∂t

D. ∇ × E =

14.

∂B ∂t

List-II 1. Ampere’s Law 2. Gauss’s Law 3. Faraday’s Law 4. Continuity equation A B C D a. 4 2 1 3 2 4 1 3 b. c. 4 2 3 1 2 4 3 1 d. Which of the following pairs of parameters and expressions is/are correctly matched? E ∈r 1. Characteristic impedance….. H

15.

16.

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18.

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2. Power flow density ……… ∇ × H 3. Displacement current in nonconducting medium ……. E × H Select the correct answer using the codes given below: a. 1 alone b. 2 and 3 c. 1 and 3 d. 1 and 2 If the electric field E = 0 . 1 te–t ax and ∈ = 4 ∈0 , then the displacement current crossing an area of 0.1 m2 at t = 0 will be a. zero b. 0.04 ∈0 c. 0.4 ∈0 d. 4 ∈0 The directivity of an isotropic antenna is a. zero b. less than unity c. unity d. infinity Consider the following statements: For a uniform plane electromagnetic wave 1. the direction of energy flow is the same as the direction of propagation of the wave. V 2. electric and magnetic fields in time quadrature. 3. electric and magnetic fields are in space quadrature. Of these statements a. 2 alone is correct b. 1 and 3 are correct c. 1 and 2 are correct d. 3 alone is correct For an air dielectric transmission line. It is found that as the frequency is varied from 50 MHz upward, the current reaches a minimum at 50-01 MHz and then a maximum at 50.04 MHz the distance of the location of the short-circuit from the generator will then be a. 10 km b. 2.5V km c. 1 km d. not determinable from the given data Consider the following statements: Piezoelectric materials are useful for converting 1. mechanical energy into electrical energy.

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3 of 15 2. electrical energy into mechanical energy. 3. mechanical energy into chemical energy. 4. chemical energy into mechanical energy. Of these statements a. 1 and 2 are correct b. 1, 2, 3 and 4 are correct c. 1 alone is correct d. 2, 3 and 4 are correct Which one of the following classes of materials can be categorised as ferrites? a. Plastics b. Metals c. Alloys d. Ceramics Consider the following in relation to the orbital motion of an electron : 1. State of energy level 2. Orbital angular momentum 3. Angle between the applied magnetic field and angular momentum. The quantum numbers, I, m and n of an electron in orbit represent respectively a. 1, 2 and 3 b. 2, 3 and 1 c. 3, 2 and 1 d. 3, 1 and 2 The correct sequence of increasing order of electrical resistivity of the given materials is a. Diamond, doped germanium, silicon, gold b. Gold, silicon, doped germanium, diamond c. Gold, doped germanium, silicon, diamond d. Gold, diamond, silicon, doped germanium Fermi level is the a. highest occupied energy level at zero kelvin b. highest occupied energy level at 0°C c. energy level at which electron emission occurs d. minimum energy level in the conduction band Which one of the following statements is correct? a. The absence of a hysteresis loop in plot Of polarization against field is proof of

25.

the absence of spontaneous polarization b. The Curie temperature of a ferroelectric is the temperature above which its spontaneous polarization disappears c. the curie temperature of a ferroelectric is the temperature below which its spontaneous. polarization disappears d. Barium titanate is a ferroelectric because its lattice strains spontaneously above the Curie temperature The first critical condition a which free electrons are diffracted in an FCC crystal would occur at which one of the following values of the wave number ‘K’/(‘a’ is lattice parameter) 2 a. a πa b. 3 c.

26.

27.

28.

29.

a. b. c.

30.

π a

3π d. a When the time period, of the applied voltage is much shorter than the relaxation time of a polarization process, the loss angle is a. zero b. between 00 and 90°. c. 90° d. greater than 90° A ferromagnetic material exhibits different characteristics above and below the a. Joule’s temperature b. Faraday temperature c. Curie temperature d. Neel temperature Consider the following statements : If the temperature is increases the resistivity of a metal increases because of 1. decrease in carrier concentration 2. an increase in the extent of scattering of carriers. 3. increase in density of impurity. Of these statements a. 1, 2 and 3 are correct b. 2 alone is correct c. 1 alone is correct

4 of 15 d. 2 and 3 are correct Which one of the following is a realistic representation of an equivalent circuit of a condenser containing a lossy dielectric?

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32.

d. The spins in a ferrimagnetic material are a. all aligned parallel b. partially aligned antiparallel without exactly canceling out sub-lattice magnetism c. randomly oriented d. all aligned antiparallel such that the sub-lattice magnetism cancels out exactly Consider the following functions: 1. To mask against diffusion or ion implant. 2. To act as a component in MOS devices. 3. To provide low resistivity paths. 4. To facilitate the entry of dopants The functions of an oxide layer on a silicon wafer would include a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 1 and 4 Match List-I (Application) with List-II (Semiconductor) and select the correct answer using the codes given below the lists : List-I A. Light emitting diode B. Gunn diode C. Thyristor D. Infra-red detector List-II 1. Si 2. Gap 3. InSb 4. GaAs A B C D

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a. 2 4 3 1 b. 4 2 3 1 4 2 1 3 c. d. 2 4 1 3 Lithium Niobate is used in a. SAW devices b. LED’s c. the manufacture of optical fibres d. laser diodes Match List-I with List-II and select the correct answer using the codes given below the Lists : List-I (Malaria) A. Paramagnetic B. Diamagnetic C. Ferromagnetic D. Ferrimagnetic List-II (Magnetic susceptibility) 1. 10–5 2. 103 – 105 3. 10–3 4. 10–102 A B C D a. 3 1 2 4 3 4 2 1 b. c. 1 3 2 4 4 1 2 3 d. Which of the following is/are the equivalent circuits of an iron-cored, valid at one frequency?

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38.

1. 2. 39.

36.

3. Select the correct answer using the codes given below: a. 1 alone b. 2 alone c. 2 and 3 d. 1, 2 and 3 A 10V battery with an internal resistance of 1Ω is connected across a non-linear load whose v-i characteristic is given by 7i = v2 + 2v The current delivered by the battery is a. 2.5 A b. 5A

40.

5 of 15 c. 6A d. 7A A voltage V is applied to an ac circuit resulting in the delivery of a current I . Which of the following expressions would yield the true power delivered by the source ? 1. Real part of VI * 2. Real part of VI V 3. F times the real part of I Select the correct answer using the codes given below: a. 1 alone b. 1 and 3 c. 2 and 3 d. 3 alone Match List-I (Loop concept) with List-II (Junction concept) and select the correct answer using the codes given below the Lists: List-I A. Mesh B. Outside mesh C. Mesh current D. Number of meshes List-II 1. Number of nodes 2. Node voltage 3. Reference node 4. Node A B C D a. 3 4 1 2 3 4 2 1 b. c. 4 3 2 1 d. 4 3 1 2 In the network shown in the figure, the effective resistance faced by the voltage source is

a. 4Ω b. 3Ω c. 2Ω d. 1Ω For the network shown in the figure, if V = V1 and V = 0, then = -5 A and if V = 0, and V1 = 1, then I = 1/2 A. The values of

Isc and R1 of the Norton’s equivalent across AB would he respectively.

41.

a. -5 A and 2Ω b. 10 A and 0.5 Ω c. 5 A and 2 Ω d. 2.5 A and 5 Ω The driving-point impedance of a one-port reactive network is given by s 2 + 1)( s 2 + 2 ) ( a. s ( s 2 + 3)( s 2 + 4 )

( s + 1)( s + 3) s ( s + 2 )( s + 4 ) s ( s + 1) ( s + 2 )( s + 3) 2

b.

2

2

2

2

c.

2

45.

2

1 s +1 The Thevenin equivalent of a network is as shown in the given figure. For maximum power transfer of the variable and purely resistive load R1, its resistance should be

6 of 15 10 5 ⎡ ⎤ ⎢ 200 200 ⎥ a. ⎢ ⎥ 10 ⎥ ⎢ 5 ⎢⎣ 200 200 ⎥⎦ −5 ⎤ ⎡ 10 ⎢ 200 200 ⎥ b. ⎢ ⎥ 10 ⎥ ⎢ −5 ⎢⎣ 200 200 ⎥⎦ −5 ⎤ ⎡ 15 ⎢ 200 200 ⎥ c. ⎢ ⎥ 15 ⎥ ⎢ 5 ⎣⎢ 200 200 ⎦⎥ 5 ⎤ ⎡ 15 ⎢ 200 200 ⎥ d. ⎢ ⎥ 15 ⎥ ⎢ 5 ⎣⎢ 200 200 ⎦⎥ The time-constant to the network shown in the figure is

d. 42.

46.

43.

44.

a. 60 Ω b. 80 Ω c. 100 Ω d. infinity If i (t) = 1/4 (I – e–2t) u (t) where u (t) is a unit step voltage, then the complex frequencies associated with i (t) would include a. s = 0 and j2 b. s = j2 and s = -j2 c. s = -j2 and s = -2 d. s = 0 and s = -2 A ‘T-network is shown in the given figure. Its Ysc matrix will (units in siemens)

47.

48.

a. CR b. 2CR c. CR/4 d. CR/2 For a two-port network to be reciprocal, it is necessary that a. Z11 = Z22 and y21 = y12 b. Z11 = Z22 and AD - BC = 0 c. h21 = -h12 and AD – BC = 0 d. y21 = y12 and h21 = - h12 Match List-I (Parameters) with List-Il (Units) and select the correct answer using the codes given below the lists: List-I A. h11 B. h12 C. h22 List-II 1. Dimensionless 2. Ohms 3. Siemens A B C a. 1 2 3 b. 1 3 2 c. 2 1 3 d. 3 2 1 Two two-port networks with transmission parametersA1, B1, C1, D1, and A2, B2, C2,

K2 ( s + 2) b. s+3 K2 s c. s+5 K2 s d. s+2

D2 respectively are cascaded. The transmission parameter matrix of the cascaded network will be ⎡ A B1 ⎤ ⎡ A2 B2 ⎤ a. ⎢ 1 ⎥+⎢ ⎥ ⎣C1 D1 ⎦ ⎣C2 D2 ⎦ ⎡A b. ⎢ 1 ⎣C1 ⎡A c. ⎢ 1 ⎣C1

49.

50.

B1 ⎤ ⎡ A2 D1 ⎥⎦ ⎢⎣C2 A2 B1

D2 D1

B2 ⎤ D2 ⎥⎦ B2 ⎤ D2 ⎥⎦

⎡ ( A A + C1C2 )( A1 B2 + B1 D2 ) ⎤ d. ⎢ 1 2 ⎥ ⎣( C1 A2 − C1C2 )( C1C2 − D1 D2 ) ⎦ An initially relaxed RC-series network with R = 2MΩ and C = 1μF is switched on to a 10 V step input. The voltage across the capacitor after 2 seconds will be a. zero b. 3.68 V c. 6.32 V d. 10 V On eliminating the feedback loop in the system shown in the figure,

52.

53.

54.

7 of 15

s+2 the initial and final s ( s + 1) values of v (t) will be respectively a. 1 and 1 b. 2 and 2 c. 2 and 1 d. l and 2 The net work function ( s + 2) F(s) = ( s + 1)( s + 3) represents an a. RC impedance b. RL impedance c. RC impedance and an RL admittance d. RC admittance and an RL impedance In the network shown in Fig. 1, if the IF capacitor had, an initial voltage of 2V, then which of the following would represent the s-domain equivalent circuits?

For V(s) =

it would lead to a simplification with a single edge of gain T12 a. 1 + T22 T22 b. 1 − T12 c. T12 T12 1 − T22 For the circuit shown in the given figure. if the input impedance Z1 at port 1 is given by K ( s + 2) Z1 = 1 s+5 then the input impedance Z2 at port 2 will be

d.

51.

a.

K 2 ( s + 3) s+5

1.

2.

3.

4. Select the correct answer using the codes given below: a. and 3

55.

56.

57.

b. 1 and 4 c. 2 and 3 d. 2 and 4 An initially relaxed 100 mH inductor is switched ‘ON’ at t = 1 sec. to an ideal 2 A dc current source. The voltage across the inductor would be a. zero b. 0.2 δ (t–1) V c. 0.2 δ (t–1) V d. 0.2 tu (t–l) V The current through the current coil, of a wattmeter is given by i = (1 + 2 sin ω t) A and the voltage across the pressure coil is v = (2 + 3 sin 2 ω t) V The wattmeter will read a. 8.00 W b. 5.05 W c. 2.0 W d. 1.0 W In the circuit shown in the figure, vs = cos 2t, Z 2 = 1 + j. C1 is so chosen that i = 1 cos 2t. The value of C1 is

61.

62.

63.

58.

59.

60.

a. 2 F b. 1 F c. 0.5 F d. 0.25 F An RLC resonant circuit has a resonance frequency of 1.5 HMz and a bandwidth of 10 kHz. If C = 150 pF, then the effective resistance of the circuit will be a. 29.5 Ω b. 14.75 Ω c. 9.4 Ω d. 4.7 Ω A 3-phase, 3 wire supply feeds a load consisting of three equal resistors connected in star. If one of the resistors in open circuited, then the percentage reduction in the load will be a. 75 b. 66.66 c. 50 d. 33.33 Two identical coils of negligible resistance, when connected in series across

64.

65.

66.

67.

8 of 15 a 50 Hz fixed voltage source, draw a current of 10A. When the terminals of one of the coils are reversed, the current drawn is 8A. The coefficient of coupling between the two coils is a. 1/100 b. 1/9 c. 4/10 d. 8/10 The voltage-ratio transfer function of an active filter is given by V2 ( s ) (s 2 + δ ) = 2 V1 ( s ) ( s + α s + δ ) The circuit in questions a a. low- pass filter b. high-pass filter c. band-pass filter d. band-reject filter Swamping resistance is a resistance which is added to the moving coil of meter to a. reduce the full-scale current b. reduce the temperature error c. increase the sensitivity d. increase the field strength The dimensional equation of resistance is a. L2 MT–2 I–2 b. L2 MT–2 I–2 c. L2 M–3 I–2 d. L2 MT–3 I–2 A high frequency ac signal is applied to a PMMC instrument. If the rms value of the ac signal is 2 V, then the reading of the instrument will be a. zero b. 2V c. 2 2V d. 4 2V The resistance of a shunt for a precision grade ammeter can be best measured by a. De Sauty bridge b. Scherring bridge c. Maxwell bridge d. Kelvin double bridge Which one of the following has the highest accuracy? a. Standard resistance b. Standard inductance c. Standard capacitance d. Standard mutual inductance In the circuit shown in the figure, is the ammeter indicated 1A, and the voltmeter

having an internal resistance of 1 kΩ indicated 100 V, then the value of R would be 71.

68.

69.

a. 111.11 Ω b. 105.2 Ω c. 100 Ω d. 90.9 Ω The current ‘I’ through a resistance R is measured with the following uncertainties I = 4A ± 0.5 % R= 100 Ω ± 0.2% If power is computed from these two measured quantities, the uncertainty in the power computed will be a. ± 0.01% b. ± 0.29 % c. ± 0.07 % d. ± 1.2 % In the balanced Wheatstone bridge shown in the figure. If the value of R6 is increased, the current I2

72.

73.

74.

a. b. c. d.

70.

will increase will decrease will remain unchanged may increase of decrease depending upon the values of the other five resistances Match List-I, with List-Il and select the correct answer using the codes given below the Lists : List-I A. Low value, of R B. High- Q inductor C. Low - Q inductor D. High voltage capacitors List-II 1. Scherring bridge 2. Maxwell bridge 3. Kelvin double bridge 4. Hay bridge A B C D a. 1 2 4 3

75.

76.

9 of 15 b. 1 4 2 3 c. 3 2 4 1 d. 3 4 2 1 An indicating instrument is more sensitive if its torque to weight ratio is a. much larger than unity b. of the order of unity c. much less than unity d. made deflection-dependent The X-and Y - inputs of a CRO are respectively V sin ωt and -V sin ωt. The resulting Lissajous pattern will be a. a straight line b. a circle c. an ellipse d. a figure of eight A current i = (10 + 10 sin t) amperes is passed through an ideal moving iron type ammeter. Its reading will be a. zero b. 10 A 150 A c. d. 10 2A In a Q-meter, a small resistance R is added to the series resonance circuit to inject the oscillatory voltage to the circuit. If Rs is the apparent series resistance of the circuit at resonance, then the value of the actual Q will be equal to 1 a. observed Q R 1+ Rs ⎛ R⎞ b. observed Q ⎜1 + ⎟ ⎝ Rs ⎠ 1 c. Observed Q R 1+ s R ⎛ Rs ⎞ d. Observed Q ⎜1 + ⎟ R⎠ ⎝ In a flux meter, the controlling torque is a. produced by weights attached to the moving coil b. produced by springs c. not provided at all d. provided by crossed coil mechanism Dummy strain gauge is used in conjunction with the main strain gauge to a. calibrate the system b. compensate temperature effects. c. improve sensitivity

77.

78.

79.

80.

81.

82.

d. reduce strain on the main gauge In a two-wattmeter method of measuring power, one of the watt- meters is reading zero watts. The power factor of the circuit is a. Zero b. 1 c. 0.5 d. 0.8 Hall effect device can be used to a. multiply two signals b. divide one signal by another on .an instantaneous basis c. add two signals d. subtract one signal from another Match List-I (Transducer) with List-II (Input/Output variables) and select the correct answer using the codes given below the Lists: List-I A. Electrodynamic generator B. Venturimeter C. Pirani gauge D. Spring balance List-II 1. Gas pressure to resistance change 2. Force to displacement 3. Motion to voltage 4. Flow rate to pressure A B C D a. 2 1 4 3 b. 2 4 1 3 3 4 1 2 c. d. 3 4 2 1 Doppler shift principle is used in the measurement of a. temperature b. frequency c. speed d. pressure In distortion factor meter, the filter is used to suppress a. dc component b. odd harmonics c. even harmonics d. fundamentals Which of the following measurements can be made with the help of a frequency counter? 1. Fundamental frequency of input signal. 2. Frequency components of the input signal at least upto third harmonic.

83.

84.

85.

10 of 15 3. Time interval between two pulses. 4. Pulse width. Select the correct answer using the codes given below: a. 1, 3 and 4 b. 1, 2 and 3 c. 2 and 4 d. 1 and 2 The bandwidth requirement of an FM telemetry channel is a. equal to that of an AM telemetry channel b. smaller than that of an Am telemetry channel c. about 100 times that of an AM telemetry channel d. about ten time that of an AM telemetry channel The recording head in a magnetic tape responds to a. electrical signal and creates a magnetic signal b. thermal signal and creates a magnetic signal c. magnetic signal and creates an electrical signal d. thermal signal and creates an electrical signal When the signal flow graph is as shown in the figure, the overall transfer function of the system will be

C =G R C G b. = R 1+ H2 C G c. = R (1 + H 2 )(1 + H 2 ) a.

C G = R 1+ H2 + H2 The block diagram shown in Fig. 1 is equivalent to d.

86.

a.

11 of 15 00

C.

∫ x (t ) e

− jwt

dt

00

b.

00

D.

∫ δ ( t )dt

00

c.

87.

d. The transfer function of a system is given by K 1 C ( jω ) = ,K < T ( jω )( jωT + 1) Which one of the following is the Bode plot of this function?

89.

List-II 1. Step function 2. Convolution integral 3. Fourier transform 4. Laplace transform A B C D a. 1 3 4 2 b. 1 4 3 2 2 3 4 1 c. d. 2 4 3 1 The magnitude-frequency response of a control system is shown in the figure. The value of ω1 and ω2 are respectively

a.

b.

90. c.

88.

d. Match List-I (Mathematical expression) with List-II (Nomenclature) and select the correct answer using the codes given below the Lists : List-I 00

A.

∫ h ( t − τ ) x (τ )dτ

00 00

B.

∫ x (t ) e

00

− st

dt

91.

a. 10 and 200 b. 20 and 200 c. 20 and 400 d. 100 and 400 A liner second-order system with the transfer function 49 G(s) = 2 s + 16 s + 49 is initially at rest and is subjected to a step input signal. The response of the system will exhibit a peak overshoot of a. 16 % b. 9 % c. 2 % d. zero A system has the following transfer function : 100( s + 5)( s + 50) G(s) = 4 s ( s + 10)( s 2 + 3s + 10) The type and order of the system are respectively a. 4 and 9 b. 4 and 7 c. 5 and 7 d. 7 and 5

92.

93.

94.

95.

The open-loop transfer function of a unityfeedback control system is: K ( s + 10)( s + 20) G(s) = s 2 ( s + 2) The closed-loop system will be stable if the value of K is a. 2 b. 3 c. 4 d. 5 Match List-I (Plot/diagram/chart) with List-II (Characteristic) and select the correct answer using the codes given below the lists : List-I A. Constant M loci B. Constant N loci C. Nichol’s chart D. Nyquist plot List-II 1. Constant gain and phase shift loci of the closed- loop system. 2. Plot of loop gain with variation of ω 3. Circles of constant gain for closed loop transfer function 4. Circles of constant phase shift of closed - loop transfer function A B C D a. 3 4 2 1 b. 3 4 1 2 c. 4 3 2 1 4 3 1 2 d. The state and output equations of a system are as under state equation: ⎡ x1 (t ) ⎤ ⎡ 0 1 ⎤ ⎡ x1 (t ) ⎤ ⎡ 0 ⎤ ⎢ x (t ) ⎥ = ⎢ −1 −2 ⎥ ⎢ x (t ) ⎥ + ⎢1 ⎥ u (t ) ⎦⎣ 2 ⎣ 2 ⎦ ⎣ ⎦ ⎣ ⎦ ⎡ x (t ) ⎤ Output equation : C (t ) = [1 1] ⎢ 1 ⎥ ⎣ x2 (t ) ⎦ The system is a. neither state controllable nor output controllable b. state controllable but not output controllable c. output controllable but not state controllable d. both state controllable and output controllable The loop transfer function GH of a control system is given by

96.

97.

98.

12 of 15 K GH = s ( s + 1)( s + 2)( s + 3) Which of the following statements regarding the conditions of the system root loci diagram is/are correct? 1. There will be four asymptotes. 2. There will be three separate root loci. 3. Asymptotes will intersect at real axis at σA = –2/3 Select the correct answer using the codes given below: a. 1 alone b. 2 alone c. 3 alone d. 1, 2 and 3 The value of A matrix in X = AX for the system described by the differential equation y + 2y + 3y = 0 is ⎡1 0⎤ a. ⎢ ⎥ ⎣ −2 −1⎦ ⎡1 0⎤ b. ⎢ ⎥ ⎣ −1 −2 ⎦ ⎡0 1⎤ c. ⎢ ⎥ ⎣ −2 −1⎦ ⎡0 1⎤ d. ⎢ ⎥ ⎣ −3 −2⎦ The minimum number of states necessary to describe the network shown in the figure in a state variable form is

a. 2 b. 3 c. 4 d. 6 Consider the following statements regarding a linear system y = f(x2) : 1. f(x1 + x) = f (x1) + f(x2) 2. f[x(t + T) = f[x(t)] + f [x(T)] 3. f(Kx) = KF(x) Of these statements a. 1, 2 and 3 are correct b. 1 and 2 are correct c. 2 alone is correct

99.

100.

101.

102.

d. 1 and 3 are correct When the input to a system was withdrawn at t = 0, its output was found to decrease exponentially from 100 units to 500 units. in 1.386 seconds.. The time constant of the system is a. 0.500 b. 0.693 c. 1.386 d. 2.000 Match List - I (System) with List - II (Transfer function) and select the correct answer using the codes given below the Lists: List-I A. AC servomotor B. DC amplifier C. Lead network D. Lag network List-II s+z 1. ( z < p) s+ p 1 + T1S (T1 < T2 ) 2. 1 + T2 S K 3. 1 + Ts K 4. s(1 + Ts ) A B C D a. 3 4 1 2 4 3 1 2 b. c. 3 4 2 1 4 3 2 1 d. Consider the following statements regarding constructional features of synchros : 1. Synchro repeater has a three-phase stator and a three-phase rotor. 2. Disc shaped rotor of the synchro control transformer offers a low reluctance to the magnetic path 3. Synchro transmitter has a frictionless bearing. Of these statements : a. 1, 2 and 3 are correct b. 1 alone is correct c. 2 alone is correct d. 2 and 3 are correct Which of the following motors would be suitable for, use as servomotors? 1. Two-phase induction motor

103.

104.

13 of 15 2. DC separately excited motor. 3. Single- phase capacitance start induction motor. 4. Universal motor. 5. Single-phase synchronous motor. Select the correct answer using the codes given below : a. l, 2, 3, 4 and 5 b. 2, 3 and 4 c. 1, 2 and 5 d. 1 and 5 The phase portrait of a non-linear system is shown in the figure. Here the origin is a

a. stable focus b. vortex c. stable node d. saddle point A closed-loop nonlinear system is shown in the figure:

The phase plane plot in e-e plane is:

a.

b.

c.

105.

d. The block diagram of a sampled data system is shown the figure:

106.

107.

108.

109.

The output C (z) of the system is given by GR( z ) a. 1 + GH ( z ) G ( z ) R( z ) b. 1 + GH ( z ) GR( z ) c. 1 + G( z) H ( z) G ( z ) R( z ) d. 1 + G( z) H ( z) Assertion (A) : Static electric field and equipotential lines are orthogonal. Reason (R) : ∫ E.dl = 0

a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The static magnetic field has zero divergence and non-zero curl. Reason (R) : They static magnetic field satisfies the flux law. a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : A glazed ceramic insulator has a lower breakdown strength than an unglazed one. Reason (R) : Glazing covers pores and cracks and makes the surface nonabsorbent. a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : In a type II. superconductor, the magnetization gradually decreases between two critical values of the applied field HC1 and HC2.

110.

111.

112.

113.

14 of 15 Reason (R) : In a type II superconductor, magnetic flux lines are pinned by micro structural imperfections. a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : In an alternating field of 1014 Hz, the electrical conductivity of a metal is zero Reason (R) : As the electrons fail to respond to the fast changing electric field, there is no drift. a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Addition of boron to intrinsic or pure silicon in the proportion of one boron atom to 1015 silicon atom increases the conductivity of pure silicon by a factor of 103 at room temperature. Reason (R) : Addition of impurities to intrinsic semiconductors increases carrier mobility. a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : A network consisting of ‘n’ nodes and ‘e’ elements can be completely analysed from (e-n +1) mesh equations or (n-1) node equations. Reason (R) : The number of mesh equations plus number of node equations is equal to the number of elements in the network. a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The poles and zeros of a reactance function alternate on the s-plane.

114.

115.

116.

117.

Reason (R) : The plot of a reactance function as a function of frequency always has a positive slope. a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The steady-state response of a linear network is termed ‘forced response. Reason (R) : The forcing function does not have any effect on the transient response of a linear system. a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion(A) : A variance is dependent on the mean value of the set of data. Reason (R) : Variance is the difference of the mean squared values and the square of the mean value of the set of data. a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The vertical deflecting plates of a CRT are kept farther away from the screen as compared to the horizontal deflecting plates. Reason (R) : This improves accuracy in measurements. a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true The Nyquist plot of a system with the loop transfer function G(s) H(s) is shown in the given figure :

Assertion (A) : The system is unstable.

118.

119.

120.

15 of 15 Reason (R) : The Nyquist plot does not encircle the critical point (-1, j0). a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : When plant parameter uncertainties are present, the open-loop structure is potentially superior to the closed loop structure. Reason (R) : When feedback is employed, there is a possibility of additional noise or uncertainty in the measurement of the plant signals. a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The compensating network shown in the given figure is used for reduction of steady-state error in the system response.

Reason (R) : A lead compensating network reduces system steady-state error. a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true A sampled data system has the following characteristic equation in the r-plane 3.5r 2 − 2.5r 2 + 0.5r + 2.5r = 0 z −1 where r = z +1 Assertion (A) : The system is unstable. Reason (R) : Not all the roots, of the characteristic equation F (z) = 0 lie within the unit circle |z| = 1 in the z - plane. a. Both A and R are true and R is the correct explanation of A b. Both A and Rare true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true

I.E.S-(OBJ) 1999

1 of 15

ELECTRICAL ENGINEERING PAPER–I 1.

2.

3.

4.

5.

Vacant lattice sites in halide crystals cause a. plastic deformation and ionic conductivity b. transparency and diffusion c. diffusion and ionic conductivity d. plastic deformation and transparency In a linear chain of atoms of interatomic distance ‘l’, the first Brillouin zone occurs between wave numbers a. −π / l and + π / l b. −2π / l and + 2π / l c. Zero and 2π / l d. −1/ e and + 1/ l The temperature coefficient of resistance of an insulator is a. positive and independent of temperature b. negative and independent of temperature c. negative and dependent on temperature d. positive and dependent on temperature Match List I (Dielectric) with List II (Loss-tangent) and select the correct answer using the codes given below: List I A. Teflon B. Polystyrene C. Bakelite D. Glass List II 1. 5 × 10-5 2. 3 × 10-2 3. 5 × 10-4 4. 7.7 × 10-3 A B C D 1 2 4 3 a. b. 3 2 4 1 c. 4 3 1 2 d. 3 1 2 4 Piezoelectric materials owe their property to the a. presence of a centre of symmetry b. lack of a centre of symmetry

6.

7.

8.

c. presence of axis of symmetry d. lack of axis of symmetry If E - EF = 2kT (EF is Fermi energy and ‘k’, the Boltzmann’s constant is 8.614 x 10-5 eVK-1), then the probability that an electron occupies an energy level ‘E’ is a. 0.63 b. 0.5 c. 0.27 d. 0.12 Match List I (Material) with List II (Superconducting transition temperature) and select the correct answer: List I A. Sn B. Nb3 Ge C. Y-Ba-Cu oxide D. Bi-Sr-Ca-Cu oxide List II 1. 23 K 2. 4 K 3. 125 K 4. 90 K Codes; A B C D 2 1 4 3 a. b. 4 1 2 3 c. 4 1 3 2 d. 1 4 2 3 Match List I (Type of magnetism) with List II (Material) and select the correct answer: List I A. Diamagnetic B. Ferromagnetic C. Antiferromagnetic D. Ferromagnetic List II 1. Ge 2. NiO 3. Ferrites 4. Cobalt. Codes; A B C D

9.

10.

11.

a. 1 4 3 2 4 1 2 3 b. c. 4 1 3 2 d. 1 4 2 3 Consider the following statements: Permanent magnet dipoles in matter result from 1. orbital angular momentum of electrons 2. electron spin angular momentum 3. nuclear spin angular momentum Which of these statements are correct? a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2 and 3 The phenomenon by which a ferromagnetic material is magnetized to its final state by a magnetic field is attributed to a. eddy currents and magnetic viscosity b. magnetic viscosity and hysteresis c. hysteresis and eddy currents d. aging and magnetic viscosity The current in a coil wound over a ferromagnetic core is gradually increased to 2 A and then reduced to 1 A and then the current in it is again increased to 2 A. The variation of magnetization of the core will be as shown in a.

12.

13.

14.

b.

c.

15.

d. 16.

2 of 15 The total iron loss in a transformer core at normal flux density was measured at 25 Hz and at 50 Hz and was found to be 250 W and 800 W respectively. The hysteresis loss at 50 Hz would be a. 100W b. 150W c. 200W d. 600W Consider the following statements: During an electron transition across the energy gap in GaAs, its 1. momentum changes 2. direction of motion changes 3. potential energy changes 4. kinetic energy remains constant Which of these statements are correct? a. 3 and 4 b. 2 and 3 c. 1 and 2 d. 1 and 4 Match List I (Semiconductor property) with List II (Type of semiconductor) and select the correct answer List I A. Electron mobility of 0.13 m2V-1s-1 B. p-type C. n-type D. Wide band gap List II 1. Germanium doped with arsenic 2. Gallium arsenide 3. Silicon 4. Gallium doped silicon Codes; A B C D a. 3 4 2 1 b. 4 3 1 2 c. 3 4 1 2 d. 4 3 2 1 The Hall coefficient of a sample of silicon having 1022 arsenic atoms per m3 is a. 3.49 × 10-3m3/C b. 6.25 × 10-4m3/C c. 1.37 × 10-4 m3/C d. 9.44 × 10-5 m3/C The ceramic dielectrics used in electrical engineering in- dude a. cermet and suicide b. porcelain and cermet c. cordierite and porcelain

17.

18.

19.

20.

d. suicide and cordierite 17. Liquid crystal maternal is used in a. ultrasonic amplification and display devices b. thermal sensors and transducers c. display devices and thermal sensors and ultrasonic d. transducers amplification Match List I (Semiconductor) with List II (Band gap in eV) and select the correct answer: List I A. GaAs B. InP C. InGaAs D. GaAIAs List I 1. 1.8 2. 1.43 3. 1.35 4. 0.75 Codes; A B C D a. 2 3 1 4 b. 2 3 4 1 c. 3 2 4 1 d. 3 2 1 4 Assertion (A): The relative dielectric constant Reason (R): With increase in frequency of the applied field, the polarization processes increase in number. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Inasemiconductor, the Hall field per unit electric current density per unit magnetic flux maybe zero. Reason (R): The Hall coefficient is proportional ( pμh2 − nμe2 ) . a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true

21.

22.

23.

24.

25.

3 of 15 Assertion (A): A piezoelectric transducer is not suitable for measurement of static pressure. Reason (R): Piezoelectric effect is a reversible phenomenon. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The mechanical systems of analog indicating instruments are critically damped. Reason (R): It is desirable that the pointer of an indicating instrument overshoots a little above its equilibrium position quickly. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The measurement of impedance by bridge method is more accurate than the direct method using indicating instruments. Reason (R): The accuracy of the detector does not affect the accuracy of measurement in a bridge method. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Electric field cannot exist inside a perfect conductor. Reason (R): For a perfect conductor a = ∞ and there is no voltage drop inside the conductor. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): In a current-carrying cylindrical conductor, the magnetic field intensity within the conductor increases linearly with radial distance.

26.

27.

Reason (R): The enclosed current increases as the square of the radial distance while the perimeter increases only as the radial distance. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): An unstable control system possesses at least a pair of complex conjugate roots in its s-plane. Reason (R): Complex conjugate roots always give rise to oscillating responses. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true If the driving-point impedance function 2s + 1 is synthesized as shown in the 2 8s + 4 s + 1 given figure, then the values of R, L and C will be respectively

29.

30.

4 of 15 The short-circuit test of a 2-port network is shown in figure-I. The voltage across the terminals AA in the network shown in figure-II will be

a. 20V b. 10V c. 5V d. 2V In a passive two-port network, the opencircuit impedance matrix is

If the input port is interchanged with the output port, then the open-circuit impedance matrix will be a.

b.

28.

a. 1, 2 and 4 b. 2, 1 and 4 c. 1, 4 and 2 d. 4, 2 and 1 If the two-port network shown in the given 2s + 1 then z(s) figure has the constant B s2 will be

c.

d.

31.

In the circuit shown in the given figure, if the switch is closed at t = 0, then the voltage v(0+) arid its derivative dv / dt |t =0+ will be respectively

a. b. c. d.

s 1/s s+1 1 + 1/s

a. 10 V and 50 V/s b. 10 V and -50 V/s

5 of 15

32.

33.

34.

35.

36.

c. 100 V and 200 V/s d. 100 V and -200 V/s Five cells are connected in series in a row and then four such rows are connected in parallel to feed the current to a resistive load of 1.25Ω. Each cell has emf of 1.5 V with internal resistance of 0.2Ω. The current through the load will be a. 3.33 A b. 23.33A c. 5A d. 1A The mutual inductance between two coupled coils is 10 mH. If the turns in one coil are doubled and that in the other are halved, then the mutual inductance will be a. 5 mH b. 10 mH c. 14 mH d. 20 mH Four resistance 80Ω, 50Ω, 25Ω and R are connected in parallel. Current through 25Ω resistance is 4A. Total current of the supply is 10 A. The value of R will be a. 66.66 Ω b. 40.25 Ω c. 36.36 Ω d. 76.56 Ω A function f(t) = sin 1.1t + sin 3.3t has the time period of a. π / 1.1 b. 2π / 1.1 c. 2π/3.3 d. π/2.2 The response shown in the given figure is the Laplace trans form of the function

a.

ω 2 (s +α ) + ω2

b.

α 2 (s +α ) + ω2

c.

s +α 2 (s +α ) + ω2

d. 37.

38.

s 2 (s +α ) + ω2

Consider the following statements: The impulse response of a linear network can be used to determine the 1. step response 2. response of the sinusoidal input 3. elements of the network uniquely 4. interconnection of network elements Which of these statements are correct? a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 1 and 4 In the circuit shown in the given figure, the response current i(t)is.

V ⎛ t ⎞ exp ⎜ − ⎟ R ⎝ RC ⎠ V δ (t ) b. R V⎡ t ⎛ t ⎞⎤ c. δ (t ) − exp ⎜ − ⎟⎥ ⎢ R⎣ RC ⎝ RC ⎠ ⎦ a.

V⎡ ⎛ t ⎞⎤ δ ( t ) − exp ⎜ − ⎟⎥ ⎢ R⎣ ⎝ RC ⎠ ⎦ In a network shown in the given figure, the value of vx would be

d.

39.

40.

a. -8/9 V b. 8/9V c. 16/9V d. -16/9 V To improve the power factor in threephase circuits, the capacitor bank is connected in delta to make a. capacitance calculation easy b. capacitance value small

41.

42.

43.

44.

45.

c. the connection elegant d. the power factor correction more effective A three-phase heating unit and induction motor are connected in parallel across a 208 V three-phase supply. Motor is rated at 5 hp, 0.9 pf with efficiency of 0.85. Heating unit is rated at 1500 W The line current will be equal to a. 185A b. 1.85 V c. 18.5 V d. 15 V If an ideal centre-tapped 1: 4 transformer is loaded as shown in the figure, the impedance measured across the terminals AA would be

a. 3Z/16 b. 3Z/18 c. 2Z/3 d. Z/6 A 10 μF capacitor is fed from an ac voltage source containing a fundamental and a third harmonic of value one-third of fundamental. The third harmonic current flowing through the Capacitor expressed as percentage of the fundamental under steady- state condition will be a. zero b. 100 c. 30 d. 90 In a two-element series circuit, the applied vo1tage and the resulting current are respectively, v(t) = 50 + 50 sin (5 × 103t) V and i(t) = 11.2 sin (5 × 103t + 63.4°)A The nature of the elements would be a. R—L b. R—C c. L — C d. neither R, nor L. nor C In a balanced Wheatstone bridge, if the positions of detector and source are interchanged, the bridge will still remain

46.

47.

48.

6 of 15 balanced. This inference can be drawn from a. reciprocity theorem b. duality principle c. compensation theorem d. equivalent theorem A voltage v(t) = 6 e-2t is applied at t = 0 to a series R - L circuit with L = 1H. If i(t) = 6[exp (-2t) - exp (-3t) then R will have a value of a. 2/3 Ω b. 1 Ω c. 3 Ω d. 1/3 Ω In the circuit shown, the switch is opened at t = 0. Prior to that switch was closed, i(t) at t = 0* is

a. 2/3A b. 3/2A c. 1/3A d. 1A Consider the following statements regarding the circuit shown in the figure. If the power consumed by 5 Ω is 10 W, then 1. I = 2 A 2. the total impedance of the circuit is 5W 3. cos φ = 0.866

49.

Which of these statements are correct? a. 1 and 3 b. 2 and 3 c. 1 and 2 d. 1, 2 and 3 In the network shown in the given figure, the Thevenin source and the impedance across terminals A — B will be respectively

7 of 15

50.

51.

52.

a. 15V and 13.33 Ω b. 50 V and 15 Ω c. 115 V and 20 Ω d. 100 V and 25 Ω For the function

a. 3 b. 1/3 c. Zero d. 2/3 An arc source of 200 V rms supplies active power of 600 W and reactive power of 800 VAR. The rms current drawn from the source is a. 10 A b. 5 A c. 3.75 A d. 2.5 A In the given 2-port network, if the drivingpoint (d. p.) impedance at port 1 is ( s + 2 ) the d. p. impedance at Z11 ( s ) = K1 ( s + 5) port 2 will be

a. b.

53.

( s + 3) Z 22 ( s ) = K 2 ( s + 5) ( s + 2) Z 22 ( s ) = K 2 ( s + 3)

c. Z 22 ( s ) = K 2

s ( s + 5)

d. Z 22 ( s ) = K 2

s s + ( 2)

The reactive power drawn from the source in the network shown in the given figure is

54.

55.

56.

57.

a. 300 VAR b. 200 VAR c. 100 VAR d. zero For a series RLC citcuit, the power factor at the lower half power frequency is a. 0.5 lagging b. 0.5 leading c. unity d. 0.707 leading If a network has all linear elements except for a few nonlinear ones, then superimpositions theorem a. cannot hold at all b. always holds c. may hold on careful selection of element values, source waveform and response d. holds in case of direct current excitations A system function has a single zero and single pole. The constant multiplier ‘K’ is 1. For the given excitation sin t, the response is 2 with 45° lagging. The system has a pole and a zero respectively at a. zero and 1 b. infinity and -1 c. -1 and zero d. zero and -1 Match List I with List II and select the correct answer: List I A. Sensitivity B. Resolution C. Accuracy D. Precision List II 1. Closeness to the true value. 2. A measure of reproducibility of the instrument 3. Ratio of response to the change in the input signal 4. Smallest change in input to which the instrument can respond Codes;

58.

59.

60.

61.

A B C D a. 3 4 1 2 3 4 2 1 b. 4 3 2 1 c. 4 3 1 2 d. In the SI system, the dimension of emf is a. M L3 T-3 I b. M L3 T-3 I-1 c. M L2 T-3 I-1 d. M-1 L2 T3 I Which one of the following techniques is adopted to reduce the self-inductance of a wire-wound standard resistor? a. Bifilar winding b. Negative impedance converter c. Force balance type flux compensation additional potential d. Providing terminals The voltage of a standard cell is monitored daily over a period of one year. The mean value of the voltage for every month shows a standard deviation of 0.1 mV. The standard deviation of the set constituted by the monthly mean values will be a. zero b. 0.1 / 12 c. 0.1/ 12 d. 0.1 A bridge is shown in the given figure. If the resistance Rs is increased from 2 kΩ to 2.5 kΩ2, the current I2 will

63.

64.

increase decrease not change increase or decrease depending on the polarity of E A dc electronic voltmeter using chopper stabilization is free from errors due to a. low CMRR b. amplifier drift c. source output impedance d. interference

62.

a.

52 + 102

b.

⎛ 102 ⎞ 52 + ⎜ ⎟ ⎝ 2 ⎠

c.

⎛ 10 ⎞ 5 +⎜ ⎟ ⎝ 2⎠

65.

66.

2

2

52 + 102 2 Two equal voltages of same frequency applied to the X and Y plates of a CR0, produce a circle on the screen. The phase difference between the two voltages is a. 30° b. 60° c. 90° d. 150° In a Q-meter, an inductor tunes to 2 MHz with 450 pF and to 4 MI-la with 90pF The distributed capacitance of the inductor is a. 30 pF b. 45 pF c. 90 pF d. 360 pF Consider the network shown in the given figure. if a voltmeter of internal resistance 10 kΩ reads V1 and V2 respectively when connected stress 5 kΩ and 10 kΩ in turn, then d.

67.

a. b. c. d.

8 of 15 In a PMMC instrument, the central spring stiffness and the strength of the magnet decrease by 0.04% arid 0.02% respectively due to a rise in temperature by 1°C. With a rise in temperature of 10°C, the instrument reading will a. increase by 0.2% b. decrease by 0.2% c. increase by 0.6% d. decrease by 0.6% When a current i(t) = 5 + 10 cos 314t is measured by an electrodynamics ammeter, the meter will read

a. V1 > V2/2 b. V1 < V2/2 c. V1 = V2/2

68.

69.

70.

71.

d. V1 = 6.67 V Consider the following statements: A current transformer, is used for measurement of large currents to 1. Isolate the instrument from a hi9h voltage bus bar. 2. increase the accuracy of measurement 3. decrease the cost of measuring arrangements 4. extend the range of measurement of a conventional ammeter on ac Which of these statements are correct? a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 1 and 4 If the readings of the two wattcmeters are equal and positive in two-wattmeter method, the load pf in a. balanced 3-phase 3- wire circuit will be a. Zero b. 0.5 c. 0.866 d. Unity In the circuit shown in the given figure, the wattmeter reading will be

a. .480W b. 640 W c. 800 W d. 1000 W Consider the following statements is respect of a Wine bridge 1. It is suitable for measurement of capacitance 2. It is not affected by harmonics present in the applied voltage 3. It is suitable for measurement of frequency Which of these statements are correct? a. 1, 2 and 3 b. 1 and 2 c. 2 and 3 d. 1 and 3

72.

73.

74.

75.

9 of 15 The disc of a house service energy meter of 230 V, 1, φ, 50 Hz. 5 A, 2400 rev, per kWh creeps at 1 rev, per min. The creep error (in percent) of full load unity pf is 60 a. + ×100 2400 60 × 100 b. − 2400 60 c. + ×100 1.15 × 2400 60 d. − × 100 1.15 × 2400 Consider the following statements regarding the balanced ac bridge shown in the given figure for measurement of a coil Z1 :

1. Z2 = R2 in series with L2, Z3 = R3 and Z4 = R4. 2. Z2 = R2 Z3 = R3 and Z4 = R4 in parallel with L4. 3. Z2 = R2 , Z3 = R3 and Z4 = R4 in series with L4 4. Z2 = R2 in parallel with L2, Z3 = R3 and Z4 = R4. Which of these statements are correct? a. 1 and 4 b. 1 and 2 c. 2 and 3 d. 3 and 4 A symmetrical square wave voltage is read on an average response electronic voltmeter whose scale is calibrated in terms of rms value of a sinusoidal wave. The error in the reading is a. -3.9% b. + 3.9% c. -11% d. + 11% The en½f is measured for a junction temperature difference of 20° C by thermocouples made from materials A, B

76.

77.

78.

79.

and C. The pair A - B gives an emf of 165μV, with the end of A being positive. The pair B - C gives 100 μV, with the end of C being positive. The pair A - C will give a. 265 μV with the end of A being positive b. 265 μV with the end of C being positive c. 65 μV with the end of A being positive d. 65 μV with the end of C being positive Consider the following transducers: 1. L.V.D.T, 2. Piezoelectric 3. Thermocouple 4. Photovoltaic cell 5. Strain gauge Which of these are active transducers? a. 1, 2 and 5 b. 1, 3 and 4 c. 2, 3 and 5 d. 2, 3 and 4 Consider the fallowing ND converters used commonly in digital instruments: 1. Successive approximation type 2. Flash type 3. Dual slope type The correct sequence in increasing order of their conversion times is a. 1, 2, 3 b. 2, 3, 1 c. 2, 1, 3 d. 3, 1, 2 A fixed resistor of suitable value is usually connected across a thermistor to a. decrease its resistance b. increase its sensitivity c. compensate its self-heating effect d. improve linearity Consider the systems shown in figure-I and figure-II. If the forward path gain is reduced by 10% in each system, then the variation in C1 and C2 will be respectively

80.

81.

82.

83.

10 of 15 a. 10% and 10% b. 2% and 10% c. 5% and 1% d. 10% and 1% The block diagrams shown in figure-I and figure-II are equivalent if ‘X’ (in figure-II) is equal to

a. 1 b. 2 c. S + 1 d. S + 2 For the system shown in the given figure, the steady-state value of the output c(t) is

a. 0 b. 1 c. ∞ d. dependent on the values of K and Kt The signal flow graph shown in the given figure has

a. three forward paths and two nontouching loops b. three forward paths and three loops c. two forward paths and two nontouching loops d. two forward paths and three loops In the system shown in the given figure, to eliminate the effect of disturbance D(s) on C(s), the transfer function Gd(s) should be

86.

a.

( s + 10 )

10 s ( s + 10 ) b. 10 10 c. s + 10 10 d. s ( s + 10 ) 84.

The Bode plot shown in the given figure has G(jω) as

a. b. c. d. 85.

87.

100 jω (1 + j 0.5ω )(1 + j 0.1ω )

The natural frequency and the damping factor of the system are respectively a. 10 rad/s and 0.6 b. 10 rad/s and 0.8 c. 6 rad/s and 0.6 d. 6 rad/s and 0.8 Match List I (Roots in the ‘s’ plane) with list II (Impulse response) and select the correct answer: List I A. A single root at the origin B. A single root on the negative real axis C. Two imaginary roots D. Two complex roots in the right half plane List II 1.

2.

100 jω ( 2 + jω )(10 + jω )

3.

10

jω (1 + 2 jω )(1 + 10 jω ) 10 jω (1 + 0.5 jω )(1 + 0.1 jω )

The polar plot of 0 ≤ ω ≤ ∞ in G-plane is a.

G (s) =

4. 1+ s 1 + 4s

for

5.

Codes;

b.

c.

88.

d.

11 of 15 The unit impulse response of a linear timeinvariant second-order system is g ( t ) = 10e −8 sin 6t ( t ≥ 0 )

A B C D a. 2 1 5 4 b. 3 2 4 5 c. 3 2 5 4 2 1 4 5 d. The root-locus of a unity feedback system is shown in the given figure. The openloop transfer function of the system is

89.

90.

91.

a.

K s ( s + 1)( s + 3)

b.

K ( s + 1) s ( s + 3)

c.

K ( s + 3) s ( s + 1)

d.

Ks ( s + 1)( s + 3)

92.

93.

Match List I with List II in respect of the open-loop transfer function K ( s + 10 ) ( s 2 + 20 s + 500 ) and G (s) = s ( s + 20 )( s + 50 ) ( s 2 + 4 s + 5 )

select the correct answer: List I(Types of loci) A. Separate loci B. Loci on the real axis C. Asymptotes D. Breakaway points List II (Numbers) 1. One 2. Two 3. Three 4. Five Codes; A B C D a. 3 4 2 1 b. 3 4 1 2 c. 4 3 1 2 d. 4 3 2 1 If the characteristic equation of a closedloop system is K 1+ =0 s ( s + 1)( s + 2 ) the centroid of the asymptotes in rootlocus will be a. Zero b. 2 c. -1 d. -2 The open-loop transfer function of a unity 10 feedback control system is . The 3 ( s + 5) gain margin of the system will be a. 20 dB b. 40 dB c. 60 dB d. 80 dB

94.

95.

96.

12 of 15 The characteristic equation of a feedback control system is s 3 + Ks 2 + 5s + 10 = 0 For the system to be critically stable, the value of K should be a. 1 b. 2 c. 3 d. 4 The Nyquist plot of the open-loop transfer function of a feedback control system is shown in the given figure. If the openloop poles and zeros are all located in the left half of the s-plane, then the number of closed-loop poles in the tight half of the splane will be

a. Zero b. 1 c. 2 d. 3 The control system shown in the given figure has an internal rate feedback loop. The closed-loop system for open and close conditions of switch will be respectively

a. unstable and stable b. unstable and unstable c. stable and unstable d. stable and stable The transfer function of a lead compensator is 1 + 0.12 s GC ( s ) = 1 + 0.04 s The maximum phase shift that can be obtained from this compensator is a. 60° b. 45° c. 30° d. 15° A system is represented by

If state variables are x1 = y, x2 = y and x3 = &&& y , then the coefficient matrix ‘A’ will be a.

b.

c.

d. 97.

98.

⎡0 ⎢0 ⎢ ⎢⎣ −6 ⎡0 ⎢0 ⎢ ⎢⎣ −2 ⎡0 ⎢0 ⎢ ⎢⎣ −6 ⎡0 ⎢0 ⎢ ⎣⎢ −2

0⎤ 0 1 ⎥⎥ −5 −2 ⎥⎦ 1

0⎤ 0 1 ⎥⎥ −5 −6 ⎥⎦ 1

99.

1⎤ 1 0 ⎥⎥ −5 −2 ⎥⎦ 0

1⎤ 1 0 ⎥⎥ −5 −6 ⎦⎥ 0

100.

The state equation of a linear system is given by X = AX + BU, where ⎡ 0 2⎤ ⎡0 ⎤ A=⎢ and B = ⎢ ⎥ ⎥ ⎣ −2 0 ⎦ ⎣ −1⎦ The state transition matrix of the system is ⎡e2t 0 ⎤ a. ⎢ 2t ⎥ ⎣0 e ⎦ ⎡ e−2t 0 ⎤ b. ⎢ 2t ⎥ ⎣ 0 e ⎦ ⎡ sin 2t cos 2t ⎤ c. ⎢ ⎥ ⎣ − cos 2t sin 2t ⎦

limit cycle is

101.

⎡ cos 2t sin 2t ⎤ d. ⎢ ⎥ ⎣ − sin 2t cos 2t ⎦ The system shown in the given figure relates to tempera- hire control of air flow

Equation of heat dT 10 A + TA = u dt Temperature sensor dTs 2 + Ts = TA dt

exchanger

is

equation

is

The closed-loop transfer function of the system is

TA ( s ) TR ( s )

13 of 15 4s + 2 a. 20 s 2 + 12 s + 3 4s + 2 b. 2 20 s + 12 s + 1 2 c. 2 20 s + 12 s + 1 2 d. 2 20 s + 12 s + 3 A non-linear control system is described by the equation θ + k sin θ = 0.The types of singular point at A = (0, 0) and B = (π, 0) will be respectively a. centre and saddle b. centre arid focus c. focus and saddle d. saddle and centre A non-linear control system is shown in the figure. If the intercept of G(jω) on the negative real axis of G-plane is ( −π / 2, + j 0 ) , then the amplitude of the

102.

a. m b. 2 m c. 3 m d. 4 m Consider the following statements regarding hold circuits for the reconstruction of sampled signals: 1. Hold circuits are essentially low pass filters. 2. A first order hold circuit introduces less phase lag in comparison to zero hold circuit. 3. A zero order hold has a flat gainfrequency over the frequency range of 2π 0≤ω ≤ . where T is the sampling T period. Which of these statements is/are correct? a. 3 alone b. 1 and 2 c. 2 and 3 d. 1 alone The overall pulse transfer function of the system shown in the given figure is

a. b. c. d. 103.

14 of 15 maximum voltage of 24 V. If the capacitor is half filled with a liquid of dielectric constant 4 as shown in the given figure, then the capacitor will withstand a maximum voltage of

1 − exp ( −1) Z − exp ( −1) Z ⎡⎣1 + exp ( −1) ⎤⎦

( Z − 1) ⎡⎣ Z + exp ( −1) ⎤⎦ 1 + exp ( −1) Z + exp ( −1) Z ⎡⎣1 − exp ( −1) ⎤⎦ ( Z − 1) ⎡⎣ Z − exp ( −1)⎤⎦

For the volume charge density ρv the divergence of the electric field intensity will be equal to. a. ρv / ε 0

107.

b. ε 02 ρv c. ε 0 ρ v d. ρ v / ε 02 104.

105.

If the static magnetic flux density is B , then r r a. ∇ × B = 0 r r r b. ∇.B = 0 rr c. ∇B = J r r r d. ∇ × B = J In the given figure, the normal and tangential components of the current r density J at the interface of the boundary satisfy which one of the following sets of conditions?

108.

109.

a.

Jn1

b.

Jn1

σ 1ε1

c.

Jn1 = Jn2 and σ 1 Jt2

σ1

=

σ2

=

d. Jn1 = 106.

Jn2 Jn2

and Jt1 = Jt2

σ 1ε 2

and Jt1 = Jt2

σ 1 Jn2σ 2 Jt Jt = and 1 = 2 ε1 ε2 σ1 σ 2

A parallel plate capacitor of gap‘d’ with air as the dielectric can withstand a

110.

a. 60V b. 30V c. 20V d. 15V An anisotropic dielectric is characterized by the permittivity tensor 4 2 2⎫ ⎪ ε = ε0 2 4 2⎬ 2 2 4 ⎪⎭ r r r r For given E = 2 ( ix + iv + iz ) , the r displacement density vector D will be r r r a. 2ε 0 ( 4ix + 2iy + 2iz ) r r r b. 2ε 0 ( 2ix + 4iy + 2iz ) r r r c. 2ε 0 ( 2ix + 2iy + 4iz ) r r r d. 2ε 0 ( 8ix + 8iy + 8iz ) In a dielectric medium of relative permittivity 4, the electric field intensity is r 20 sin (108 t - βz) a y V/m and z being in m. The phase shift constant β is a. 1/3 rad/m b. 2/3rad/rn c. 2π /3 rad/m d. 1 / 6π rad/m Consider the following statements: Transmission of a modulated signal in a communication system can take place by means of 1. coaxial cables 2. optical fibres. 3. open-wire transmission lines 4. waveguides Which of these statements are correct? a. 1, 2 and 3 b. 2, 3 and 4 c. 1 and 4 d. 1, 2, 3 and 4 The unit of the Pointing vector is

15 of 15

111.

112.

a. Power b. power density c. energy d. energy density The equation r r r E = ax E sin (ωt − β z ) + a y E sin (ωt − β z ) represents a. a left circularly polarized wave b. a right circularly polarized wave c. a linearly polarized wave d. an elliptically polarized wave The intrinsic impedance of free space is a. 377Ω b. μ0ε 0 c.

j μ 0ε 0

b. E A EB2 = EB3 c. E A EC = EB2 d. E A EB = EC2 116.

117.

118.

d. ε 0 / μ0 113.

114.

115.

Consider the following pairs of types of energy transmission and practical lower frequency limit: 1. Transmission lines .... Zero 2. Optical fibres ... 300 MHz 3. Antennas.... 100 MHz Which of these pair(s) is/are correctly matched? a. 2 and 3 b. 1 and 2 c. 1 alone d. 3 alone If the electric field component of a wave is E = cos (6 × 108 πt + 50z) ax V/m, then the wave a. propagates in -x direction b. amplitude is 2 V/m c. is not traveling in free space d. propagates in + z direction A plane electromagnetic wave is travelling in a highly dissipative medium in the direction ABC as shown in the figure. The electric field EA, EB, and EC at point A, B and C respectively are related as

119.

120.

Cavity resonators are used in a. MF band b. HF band c. VHF band d. SHF band The reflection coefficient at the load end of a short-circuited line is a. zero b. 1∠0° c. 1∠90° d. 1∠180° The operator ‘del’ ∇ is a a. vector space function b. vector time function c. scalar space function d. scalar time function The magnitude of the magnetic flux density ‘B’ at a distance ‘R’ from an infinitely long straight current filament is μ01 a. 2R μ 01 b. 2π R μ 01 c. 4π R μ01 d. 8π R 2 If a plane electromagnetic wave traveling r r r r r in the direction β = ax β x + a y β y + az β z has rr electric field E = A cos ωt − β .r , then the

(

phase velocities vx : v y : vz is equal to a.

1

β

2 x

:

1

β

2 y

:

1

β z2

b. β x2 : β y2 : β z2 c.

1

:

1

:

1

βx βy βz

d. β x : β y : β z a. E A2 EC = EB3

)

I.E.S-(OBJ) 2000

1 of 17

ELECTRICAL ENGINEERING PAPER-I 1.

Match List I (Components) with list II (Transfer functions) and select the correct answer: List I A. ac servo motor B. Field controlled dc servo motor C. Tacho generator D. Integrating gyro List II K 1. s (1 + sτ m ) 2.

2.

a.

b.

K s (1 + sτ m )(1 + sτ m )

3. Ks K 4. 1 + sτ A B C D a. 1 2 3 4 1 2 4 3 b. c. 2 1 3 4 d. 2 1 4 3 Consider the following sampled data systems:

c.

4.

1.

5. 2.

3.

3. Which of these systems are similar? a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2 and 3 A two-tank system is shown in Figure — I. The electrical equivalent of this system is

d. For the system + axx ± bx = 0, the equation for the phase-plane isocline of slope m is a. m2 + am + b = 0 bx b. m = – ax – x bx c. m = ax + x 2 d. m + axm + b = 0 For the determination of stability of a nonlinear control system by the Describing Function method, the plots of C (jω) and — 1 / N(x) are drawn as shown in the given figure for an input x = X sin ωt. The types of limit cycles at the points P and Q will be respectively

a. stable and stable b. stable and unstable

6.

c. unstable and stable d. unstable and unstable A closed-loop system is shown in the given figure. The noise transfer function C(s) / N(s) [Cn(s) = output corresponding to noise input N(s) is approximately

a.

9.

c. −

1 for G1(s) H1(s) H2(s)| >> 1 H1 (s)

b.

1 for |G1(s) H1(s) H2(s)|>>1 H1 (s)H 2 (s)

1 for |G1(s) H1(s) H2(s)| G(s)H1 (s)H 2 (s) 1 / 2 f0 b. < 2 / f0 c. < 1 / 2 f1 d. > 2 / f 1 For insulators, the forbidden gap is of the order of a. 5ev b. 1 ev c. 0.1 ev d. zero Which one of the following materials does not have a covalent bond? a. Metal b. Silicon c. Organic polymers d. Diamond Match List I (Type of polarization) with List II (Signal frequency) and select the correct answer :

27.

28.

29.

30.

List I A. Electronic polarisation B. Ionic polarisation C. Orientational polarisation D. Space charge polarisation List II 1. 102 Hz 2. 1014 Hz 3. 106 Hz 4. 1012 Hz A B C D 2 1 3 4 a. 3 4 2 1 b. c. 2 4 3 1 3 1 2 4 d. Piezoelectric effect is generally observed in a. Insulators b. insulators and semiconductors c. conductors and superconductors d. conductors and semiconductors The conductivity of material ‘A’ is half that of material ‘B’. The ratio of relaxation time of ‘A’ to that of ‘B’ is a. 0.5 b. 1 c. 2 d. 4.1 According to the BCS theory, a material goes into superconducting state when electron-pairs participate in the following events: 1. Lattice distorts as a free electron A attracts a lattice ion Temperature is decreased 2. Energy of electron B is lowered and it forms a pair with electron A 3. A phonon is created which interacts with electron B The correct sequence of occurrence of these events is : a. 2, 1, 3, 4 b. 1, 2, 3, 4 c. 2, 1, 4, 3 d. 1, 2, 4, 3 Match List I (Magnetic parameters) with list II (Electric parameters) on the basis of analogy in definition and select the correct answer :

31.

32.

33.

34.

5 of 17 List I A. Magnetic field B. Flux density C. Magnetization List II 1. Electric dipole moment per unit volume 2. Electric force per unit positive charge 3. Dielectric density A B C 2 3 1 a. 3 1 2 b. 1 3 2 c. 1 2 3 d. High frequency transformer cores are generally made of a. cast iron b. mu-metal c. ferrite d. graphite A current of 50 A is passed through a metal strip which is subjected to a magnetic flux density of 1.2 Wb/m2. The magnetic field is directed at right angles to the current direction. Thickness of the strip in the direction of the magnetic field is 0.5 mm. If the Hall voltage is found to be 150 V, the number of conduction electrons per m3 in the metal is a. 5 × 1027 b. 0.5 × 1027 c. 50 × 1027 d. 5 × 1026 In the optical fibre used for communication, the core and cladding material used are respectively a. pure silica and Ge-doped silica b. P-doped silica and Ge-doped silica c. Ge-doped silica and P-doped silica d. Ge-doped silica and pure silica Match List I (Materials) with List II (Applications) and select the correct answer: List I A. Tantalum B. Graphite C. Refractory metal D. Polysilicon List II

Schottky gate Cryotron IC -technology Furnace A B C D 2 3 1 4 a. b. 1 4 2 3 1 3 2 4 c. 2 4 1 3 d. The band-gap of a semiconductor is 1.43 ev. Its cut-off wavelength is a. 1 mm b. 0.81 mm c. 0.56 mm d. 0.27 mm Match List I (Semiconductor parameters) with List II (Physical processes) and select the correct answer : List I A. Impurity concentration B. Carrier mobility C. Carrier life time D. Intrinsic carrier concentration List II 1. Recombination 2. Band to band transition 3. Scattering 4. Ion implantation A B C D 3 4 2 1 a. 4 3 2 1 b. 3 4 1 2 c. d. 4 3 1 2 Match List I (Materials) with List II (Thermal conductivity) and select the correct answer : List I A. Constantan B. Carbon C. iron D. Quartz List II 1. 4.2 W m–1 deg–1 2. 12.6 W m–1 deg–1 3. 22.5 W m–1 deg–1 4. 67.0 W m–1 deg–1 A B C D 3 4 1 2 a. 1. 2. 3. 4.

35.

36.

37.

38.

39.

40.

41.

6 of 17 b. 2 1 4 3 3 1 4 2 c. 2 4 1 3 d. Consider the following statements: In the case of paramagnetic materials, there 1. is no permanent dipole moment. 2. are permanent dipole moments. 3. is no alignment of dipoles in the absence of magnetic field. 4. is no interaction among the dipoles. Which of these statement(s) is/are correct? a. 1 alone b. 3 and 4 c. 2 and 4 d. 2, 3 and 4 Consider the following statements: There will be no spontaneous polarization, if 1. there is no hysteresis loop in a plot of polarization against field 2. there is a hysteresis loop in a plot of polarization against field 3. the material is below the Curie temperature 4. the material is above the Curie temperature Which of these statements are correct ? a. 1 and 3 b. 1 and 4 c. 2 and 3 d. 2 and 4 Consider the following types of semiconductors : 1. n-type 2. p-type 3. Intrinsic 4. Extrinsic Which of these statements are correct ? a. 1 and 3 b. 2 and 4 c. 1 and 4 d. 2 and 3 Consider the following properties: 1. Perfect diamagnetism 2. Ionic conductivity 3. Magnetic field causes an increase in transition temperature

42.

43.

44.

45.

4. Loss of superconductivity in long circular wire by large currents Which of these properties are exhibited by a superconductor? a. 1, 2 and 3 b. 2, 3 and 4 c. 1, 3 and 4 d. 1, 2 and 4 Assertion (A) : The basic principle of operation of a Q-meter is based on the property of a series-resonant circuit. Reason (R) : If a fixed voltage is applied to a series resonant circuit, the voltage developed across its capacitor is Q times the applied voltage. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : In a good quality, cassette audio tape recorder, ac bias is provided for recording purposes to improve the quality. Reason (R) : The ac bias provided for re cording in an audio tape recorder takes care of the non-linearity of the recording head. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : A spectrum analyzer is an instrument which displays the spectrum of the input waveform with respect to the frequency. Reason (R) : A spectrum analyzer consists of an internal sweep voltage generator connected to the X-deflecting plate of the CRT. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The opening of the secondary circuit of a current transfer results in a very high voltage in the

46.

47.

48.

7 of 17 secondary winding with consequent severe strain on the insulation and danger to the operator. Reason (R) : The high magnetic forces acting on the core, if suddenly removed, may leave behind considerable residual magnetism in the core. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The stability of a closedloop system can be obtained from the open-loop transfer function G(jω) H(jω) plot with respect to the critical point (–1, j0) in G(jω) H(jω) plane. Reason (R) : The origin of 1 + G(jω) H(jω) corresponds to (–1, j0) point in G(jω) H(jω) plane. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The closed-loop system C (s) 5 = for a step input can R ( s ) ( s + 1)( s + 5) C ( s) 1 = be approximated by a system 1 R( s) s + 1 1 for R(s) = . s C ( s) C (s) and 1 have Reason (R) : Both R( s) R( s ) approximately the same transient response. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true In the given figure, a single-turn rectangular loop moves with uniform velocity ‘v’ through a region of uniform magnetic flux density B , the direction of B being perpendicular to the plane of the loop.

49.

50.

51.

Assertion (A) : The emf induced in the loop is maximum during the interval the loop is fully inside the region of B . Reason (R) : Induced emf = –∂ / ∂t (flux linkage). a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Low frequencies are more suitable than high frequencies for underwater communication and for communication with underwater objects. Reason (R): Electric and magnetic fields in the underwater objects are out of phase by 45°. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Storage of energy in a dielectric is due to shift in relative positions of internal charges against normal atomic and molecular forms. Reason (R): All dielectrics are characterised by the presence of molecules having permanent displacement between the centres of gravity of the positive and negative charges. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : dc resistance of ferrites is much higher than that of dia-, para- or ferro- magnetic materials. Reason (R) : Ferrites are obtained by replacing divalent ferrous ion in

52.

53.

54.

8 of 17 ferrimagnetic magnite by another divalent metal such as Mg, Zn etc., but the exchange interactions are antiferromagnetic type. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : In the circuit shown in the figure, five current equations are required to calculate the independent branch currents and four voltage equations are required to determine the independent branch voltages.

Reason (R): The number of current equations is b – n + 1 and the number of voltage equations is n – 1 where b is the number of branches and n is the number of nodes for a circuit. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : A driving - point function should have its poles and zeros to the left half of s - plane. Reason (R) : Only a positive real function can be realized in network form. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : If the impulse response of a network is available, the response to any arbitrary input can be derived. Reason (R) : The Laplace transform of unit impulse is unity.

55.

a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Consider the following functions: 1.

s 3 + 3s 2( s 2 + 1)

2.

s 4 + 3s + 1 5( s 2 + 1)

3.

s2 +1 3s

58.

59.

3( s 3 + 7 s / 2) s 4 + 14 s 2 + 30 Which of these are valid driving- point impedance functions? a. 1, 2 and 3 b. 1, 3 and 4 c. 1, 2 and 4 d. 2, 3 and 4 Consider the following driving -point functions : 4.

56.

F1 =

( s 2 + 1)( s 2 + 3) , s ( s 2 + 4)

F2 =

( s + 1)( s + 3) , ( s 2 + 2)( s 2 + 4)

F3 =

s ( s 2 + 3) and ( s 2 + 2)( s 2 + 4)

2

2

( s 2 + 2)( s 2 + 5) s ( s 2 + 4) Among these, the LC functions would include a. F1 and F2 b. F2 and F3 c. F3 and F4 d. F1 and F4 A driving - point impedance function is given by ( s + k1 )( s + k2 )( s + k3 ) F= ( s + 1)( s + 2)( s + 3)( s + 4) The product k1k2k3 cannot be more than a. 48 b. 24 c. 10

60.

61.

9 of 17 d. 4 The hot resistance of the filament of a bulb is higher than the cold resistance because. the temperature coefficient of the filament is a. negative b. infinite c. zero d. positive The Laplace transform of the function f(t) is F(s). u(t) represents the unit step function. The inverse Laplace transform of e–s F(s) is a. f(t) u(t–1) b. f(t–1) u(t) c. f(t–1) u(t–1) d. f(t)/(t–1) If the unilateral Laplace transform X(s) of 7 s + 10 a signal x(t) is , then the initial s ( s + 2) and final values of the signal would be respectively. a. 3.5 and 5 b. zero and 7 c. 5 and zero d. 7 and 5 In the circuit shown in Figure I, the switch ‘k’ was initially at position ‘1’ and a current ‘I’ was flowing through the inductor ‘L’ and a voltage ‘V0’ existed across the capacitor ‘C’.

F4 =

57.

If at t = 0, the switch ‘k’ is put on the position ‘2’ in the circuit shown in Figure I, which one of the following transformed circuits will give i(t) for t > 0 ?

a.

10 of 17

b.

66. c.

62.

63.

64.

65.

d. In the case of the RLC circuit shown in the given figure, the voltage across the R, L and C would be respectively

a. 12V, 16V and 7V or 25V b. 16V, 12V and 7V or 25V c. 7V, 16V and 12V d. 16V, 12V and 25V In an amplifier, the increase in gain is 12dB if the frequency doubled. If the frequency is increased by 10 times, then the increase in gain will be a. 2.4 dB b. 20 dB c. 40 dB d. 60 dB For a second order system, if both the roots of the characteristic equation are real, then the value of damping ratio will be a. less than unity b. equal to unity c. equal to zero d. greater than unity If the resonant frequency of the circuit shown in Figure I is 1 kHz, the resonant frequency of the circuit shown in Figure II will be

Figure–I

67.

68.

a. 4 kHz b. 2 kHz c. 0.5 kHz d. 0.25 kHz Match List I (Readings obtained while measuring 3-phase power by twowattmeter method) with List II (Power factors for the load) and select the correct answer : List I A. Both the wattmeters read equal values of power but of opposite sign B. Both the wattmeters read equal values of power and both are of positive sign C. One wattmeter reads zero and the other reads the, complete power List II 1. Unity 2. Zero 3. 0.5 4. 0.866 A B C a. 2 3 4 b. 3 1 2 c. 1 4 3 2 1 3 d. The equivalent inductance of two coils A and B connected as in the given figure is given by

a. XL1 + XL2 — 2XM b. XL1 + XL2 + XM c. XL1 + XL2–XM d. XL1 + XL2 + 2XM A linear transformer and its T-equivalent circuit are shown in Figure I and Figure II respectively. The values of inductance La, Lb and Lc are respectively

73.

69.

70.

71.

72.

a. 1H, –2H and 2H b. –1H, 2H and 2H c. 3H, 6H and –2H d. 3H, 6H and 2H The voltage across the 1 kΩ resistor between the nodes A and B of the network shown in the given figure is :

a. 2 V b. 3 V c. 4 V 10 V d. 8 V Initially, the circuit shown in the given figure was relaxed. If the switch is closed at t = 0, the values of i(0+), di / dt (0+) and d2 i / dt2 (0+) will respectively be

a. 0, 10 and –100 b. 0, 10 and 100 c. 10, 100 and 0 d. 100, 0 and 10 If the number of branches in a network is ‘B’, the number of nodes is ‘N’ and the number of dependent loops is ‘L’, then the number of independent node equations will be a. N + L – 1 b. B – 1 c. B – N d. N – 1 A resistance of ‘R’ Ω and inductance of ‘L’ H are connected across 240 V, 50 Hz supply. Power dissipated in the circuit is 300-W and the voltage across R is 100 V. In order to improve the power factor to unity,, the capacitor that is to be connected in series should have a value of

74.

75.

11 of 17 a. 43.7 μF b. 4.37 μF c. 437 μF d. 4.37 mF The circuit shown in Figure I is replaced by its Norton’s equivalent in Figure II. The value of I’ will be

a. 2.5 ∠45° A b. 5 ∠90° A c. 10 ∠–90° A d. 15 ∠–45° A A certain network N feeds a load resistance R as shown in Figure I. It consumes a power of ‘P’ W. If an identical network is added as shown in Figure II, the power consumed by R will be

a. less than P b. equal to P c. between P and 4P d. more than 4P For the network shown in the given figure, the voltage VB will be

12 of 17

76.

a. b. c. d. In

(j 5.33) V (5.33) V (–j 5.33) V (j 3.33) the two-port network shown in the 1 given figure, if G21 (s) is 2 , then Z(s) s +1 will be

a.

b.

77.

78.

a. s b. s + 1 1 c. s 1 d. s + s Consider the following functions for the rectangular voltage pulse shown in the given figure :

1. v(t) = u(t — a) — u(t — b) 2. v(t) = u(b — t) — u(a — t) 3. v(t) = u(b — t) . u(t — a) 4. v(t) = u(a — t) . u(t — b) Which of these functions describe the pulse shown in the given figure? a. 1, 2 and 3 b. 1, 2 and 4 c. 2, 3 and 4 d. 1, 3 and 4 If a sinusoidal input is applied to the circuit shown in the given figure, the output waveform of V0 will be

c.

79.

d. Match List I {Input voltage v(t)} with List II {I(s), the Laplace transform of i(t)} for the given circuit and select the correct answer :

List I A. Unit step B. Unit ramp C. Unit impulse D. sin t List II s 1. s +1 1 2. s +1 1 3. ( s + 1) 2

4.

1 s( s + 1) A

B

C

D

80.

81.

a. 2 4 1 3 2 1 4 3 b. 3 1 4 2 c. d. 3 4 1 3 For a two-port symmetrical bilateral network, if A = 3 and B = 1 Ω, the value of parameter C will be a. 4s b. 6s c. 8s d. 16s Consider the following two-port network configurations:

83.

1.

2.

3.

82.

4. Which of these configurations relate to the definition of short- circuit admittance parameters? a. 1 and 2 b. 1 and 4 c. 2 and 3 d. 2 and 4 Match List I (Terms) with List II (Definitions) and select the correct answer: List I A. Resolution B. Precision C. Sensitivity D. Accuracy List II 1. Closeness with which the instrument reading approaches the true value V 2. Reproducibility of measurements V 3. Smallest change in measured value to which the instrument can respond

84.

85.

86.

13 of 17 4. Ratio of response of the instrument to the input variable. A B C D a. 1 2 3 4 2 1 b. 3 4 2 c. 4 3 1 d. Match List I with List II and select the correct answer,: List I (Quantity) A. Resistance B. emf C. Capacitance List II (Dimensions) 1. [M–1 L–2 T4 I2] 2. [M–1 L–2 T2 I–2] 3. [ML2 T–3 I–1] 4. [ML2 T–3 I–2] A B C 1 2 3 a. 4 2 1 b. 3 4 2 c. 4 3 1 d. To achieve, the optimum transient response, the indicating instruments are so designed as to a. be critically damped b. be undamped c. provide damping which is slightly more than the critical value d. provide damping which is slightly less than the critical value The ac bridge shown in the given figure will remain balanced if impedance Z consists of

a. resistance and inductance in series b. resistance and capacitance in parallel c. capacitance only d. inductance only In the potentiometer circuit shown in the given figure, the value of unknown voltage ‘E’ under balanced condition will be

87.

88.

89.

90.

a. 200mV b. 2.8V c. 3V d. 3.2 V A wattmeter has a range of 1000 W with an error of ±1% of full scale deflection. If the true power passed through it is 100 W, then the relative error would be a. ±10% b. ±5% c. ±1% d. ±0.5% In a permanent magnet moving coil instrument, if the control spring is replaced by another one having a higher spring constant, then the natural frequency and damping ratio will a. decrease b. increase and decrease respectively c. decrease and increase respectively d. increase Consider the following statements in respect of thermoelectric instruments : 1. They indicate the rms value of current or voltage. 2. They suffer from waveform errors. 3. They can be used for frequency ranges of the order MHz. 4. They have a low overload capacity. Which of these statements are correct ? a. 1, 3 and 4 b. 1, 2 and 4 c. 1, 2 and 3 d. 2, 3 and 4 Match List I (Type of CRO) with List II (Appropriate use) and select the correct answer : List I A. Storage B. Electrostatic deflection C. Magnetic deflection D. Multitrace

91.

14 of 17 List II 1. Voltage and current transient studies 2. Comparison of waveforms in time domain 3. Television receiver 4. Accurate voltage measurements A B C D 4 1 2 3 a. 1 4 2 3 b. 4 1 3 2 c. 1 4 3 2 d. Which one of the following resistance configurations is best suited for the construction of a low resistance? a.

b.

c.

92.

93.

94.

95.

d. High resistance are provided with a guard terminal in order to a. protect the resistance against stray electrostatic field b. bypass the leakage current c. protect the resistance against overloads d. protect the resistance against stray electromagnetic field The capacitance and loss angle of a capacitor can be accurately measured by a. Kelvin’s bridge b. Anderson’s bridge c. Schering bridge d. Carey-Foster’s bridge A resistance strain gauge is fastened to a beam subjected to a strain of 1 × 10–6, yielding a resistance change of 240 μΩ. If the original resistance of the strain gauge is 120 Ω, the gauge factor would be a. 5 b. 2 c. 1 d. 0.2 In the CR0 plate connections shown in the given figure, the supply frequency is 500

0.2

μF. The π value of resistance ‘R’ required to obtain a circle on the CRO screen (X and Y plates have equal sensitivities) is

Hz and the capacitance ‘C’ is

100.

101.

96.

97.

98.

99.

a. 2 kΩ b. 5 kΩ c. 7 kΩ d. 10 kΩ The measurement junction of a thermocouple is taken from an environment of 300° C to 600° C. If the time constant of the thermocouple is 1 s, temperature indicated by it after 1 s will be nearly a. 300°C b. 400° C c. 500° C d. 600° C In a single phase induction type energy meter, the Lag adjustment is done to ensure that a. current coil flux lags the applied voltage by 90° b. pressure coil flux lags the applied voltage by 90° c. pressure coil flux is in phase with the applied voltage d. current coil lags the pressure coil flux by 90° A voltage of {200 2 sin 314t + 6 2 sin (942t + 30°) + 8 2 cost (1570t + 30°)} V is given to a harmonic distortion meter. The meter will indicate a total harmonic distortion of approximately a. 4.5% b. 6.5% c. 7.5% d. 8.5% To eliminate 50 Hz pick-up in a dual slope DVM, the minimum period of integration of the input signal is a. 1 ms b. 20 ms

102.

103.

104.

15 of 17 c. 1 s d. 100 s Which one of the following sets of building block mainly decides the accuracy of a frequency counter? a. Crystal and ADC b. ADC and DAC c. DAC and gate width generator d. Gate width generator and crystal If the largest frequency present in the measured signal and number of bits used in the binary code, are respectively ‘fm’ and ‘n’, then the minimum bandwidth of a pulse code modulation channel used for telemetry would be a. f m / 2n b. fm / n c. nfm d. 2nfm LCD displays are preferred over LED displays because they a. are more reliable b. consume less power c. respond quickly d. are cheaper The plane x = 3 has a layer of charge density 2 nC/m2. A line charge of density 20 nC/m is located at x = 1, z = 4. The force acting on unit metre length of the line charge is a.

2 ×10−9 × 20 ×10−9 ax N 4πε 0

b.

2 ×10−9 × 20 × 10−9 az N 2πε 0

c.

2 ×10−9 × 20 ×10−9 ayN 2ε 0

d.

2 ×10−9 × 20 × 10−9 ax N 4ε 0

The electrostatic field on the surface of a ^

conductor at a certain point is 0.3 a x + ^

0.4 a y . If the normal to the surface of the conductor at that point makes an angle θ with respect to x-axis, the value of cos θ will be a. 0.8 b. 0.75 c. 0.6

16 of 17 105.

d. 0.5 A rectangular loop carrying a current is shown in the given figure The magnetic potential A at the centre ‘O’ satisfies the conditions

7.5 ×10 × 30W / m 2 3 40 ×10 3

a.

7.5 × 103 × 30 b. W / m2 3 2 4π (40 × 10 ) 7.5 × 103 × 1000 W / m2 4π (40 ×103 ) 2

c.

7.5 ×103 × 30W / m 2 (40 ×103 ) 2 The projection of d.

110.

^

A = 0 and ∇ × A ≠ 0

a.

106.

vector

^

^

b. 18 a x − 8 a y c. 10 ^

^

d. 21 a x − 28 a y 111.

If a uniform plane wave propagating. in ^

^

^

a. a x A/m

the direction (4 a x − 2 a y + a z ) has its E

b. a y A/m

field in the direction (4 a x − 2 K a y + 4 K a z ) , the value of K must be a. 2 b. –2 c. 1 d. Zero The net flux of electric field-emanating from the surface ‘S’ with location of point charges as shown in the given figure is

(a

x

^

)

+ a y A/m

The electric energy density is ‘W’ at a point in free space where the electric field ^

^

^

is a x E. If the electric field is a x E— a y E, in a dielectric of relative permittivity 4, then the electric energy density at that point will be a. Zero b. 2 W c. 4 W d. 8 W If the open- and short-circuit input impedances of a loss-less line are respectively Z1 and Z2, its characteristic impedance will be a. Z1 + Z2 b.

109.

^

d. A ≠ 0 and ∇ × A ≠ 0 A filamentary current of 10 π A flows in the negative z - direction. The magnetic field at (0, 5, 0) is

d.

108.

the

^

a. 2

A ≠ 0 and ∇ × A = 0

c. a z A/m

107.

^

6 a x + 2 a y − 3 a z along 3 a x − 4 a y is

b. A ≠ 0 and ∇ × A ≠ 0 c.

^

112.

Z12 + Z 22

c.

Z12 + Z 22 Z1 + Z 2

d.

Z1Z 2

The directive gain of an antenna is 30 dB. If the antenna radiates 7.5 kW, the power density at a distance of 40 km will be

a.

Q1 + Q2

b.

Q1 + Q2 + Q3 + Q4 + Q5

c.

Q3 + Q4 + Q5

^

^

ε0

ε0

ε0

d. ε 0 ( Q1 + Q2 ) 113.

If the 36o arc AB of a circle shown in the given figure is uniformly charges leaving the arc BCA uncharged, the electric field at the centre ‘O’ is E. If the arc BCA is given the same linear charge density and

17 of 17 electric field intensity in region z ≤ 0 is E

the arc AB left uncharged, then the electric field at the centre ‘O’ will be

^

118.

a. E b. − E c. 9 E d. −9 E ^

If B = B0z cos ωt a y and E = a x E x then

115.

a. EX = 0 b. EX = + B0z ω sin ωt c. EX = + B0 cos ωt d. EX = ½ B0 z2ω sin ωt A voltage of 50 sin 1000 t V is applied across a parallel plate capacitor with plate area of 5 cm2 and plate separation gap of 5 mm. If the dielectric material in the capacitor has ε = 2ε0, then the capacitor current (in Amperes) will be a.

104

ε0

σ ^ az 2ε 0 σ ^ b. E = a z ε0

^

114.

a. E =

^

az σ c. E = 4πε 0 z 2 d. E =

116.

104

ε0

cos 103 t

sin 103 t

d. ε0 104 sin 103 t The torque on a dipole consisting of 1 μC of charge at (0, 0, 10–3)m and –1 μC of charge at (0, 0, –10–3) m in an electric field ^ ^ ⎛ ^ ⎞ 3 ⎜ 2 ax − 2 a y − 2 az ⎟ E = 10 ⎝ ⎠ V/m. The value of torque would be ^ ⎛^ ⎞ –6 ⎜ a x + 2 a y ⎟ a. 2 × 10 ⎝ ⎠ N-m ^ ⎛^ ⎞ a x + 2ay ⎟ ⎜ b. 10 ⎝ ⎠ N-m

–6

c. –4 × 10 N-m ^ ⎛^ ⎞ d. –2 × 10–6 ⎜⎝ a x + 2 a y ⎟⎠ N-m –6

117.

The region z ≤ 0 is dielectric of relative permittivity 2 while the region z ≥ 0 is a dielectric of relative permittivity 5. If the

σ2 ^ az 4πε 0 z 2 ^

119.

b. ε0 104 cos 103 t c.

= 10 a z kV/m, the potential difference between (0, 0 –10–3) m and (0, 0, 10–3)m will be a. zero b. 70V c. 20V d. 14V An infinite plane sheet of uniform surface charge density σ C/m2 is lying in the x-y plane. The electric field E at a point P(0, 0, z) above the sheet (z > 0) would be (ε0 is the free space permittivity)

120.

^

^

If the vector B = x 2 a x − xy a y − Kxz a z represents a magnetic field, the value of the constant K must be a. 0 b. 1 c. 2 d. 3 The region z < 0 has μr = 6 and the region z > 0 has μr = 4 . If the magnetic flux ^

^

density in region z > 0 is 5 a x + 8 a z m Wb/m2, the magnetic field intensity in region z < 0 would be a.

^

^

^

^

5 ax + 8 az mA / m 4 μ0

5 ax + 8 az b. mA / m 6 μ0 ^

c.

^

5 ax 8 az mA / m + 4 μ0 6 μ0 ^

^

5 ax 8 az d. mA / m + 6 μ0 4 μ0

I.E.S-(OBJ) 2001

1 of 15

ELECTRICAL ENGINEERING PAPER-I 1.

2.

3.

Digital data acquisition systems are used 1. Only when the output of the transducers is in digital form 2. When physical process being monitored is slowly varying (narrow bandwidth) 3. When low accuracy can be tolerated 4. When high accuracy and low per channel cost is required Which of these statements are correct? a. 1, 2 and 3 b. 1, 3 and 4 c. 1 and 3 d. 2 and 4 Match list I with list II and select the correct answer: List I (Terms) A. Precision B. Accuracy C. Resolution D. Static sensitivity List II (Its meaning) 1. The smallest change in the input quantity which can be detected with its certainty 2. Closeness of the reading with its true value 3. Measure of reproducibility of the measurements 4. Ratio of infinitesimal change in output to infinitesimal change in input A B C D a. 2 3 1 4 b. 3 2 4 1 c. 3 2 1 4 d. 2 3 4 1 The modern standard of time is a. A second defined as 1/86,400 of a mean solar day b. A second defined as time constant of an RC series circuit having R = 2 MΩ, C = 500 pF c. A second which is duration of 9 192631770 periods of radiation corresponding to the transition between the two hyperfine levels of the

4.

5.

6.

fundamental state of the atom cesium 133. d. A second defined as 1/31556925.9747 of the time required by the earth to orbit the sun in the year 1900 Match List I (Error parameters) with list II (Values) and select the correct answer: (a is the standard deviation of Gaussian error): List I A. Precision index B. Probable error C. Error limit D. Pak probability density of error List II 1. 0.67 σ 2. 3 σ 3. 0.39/ σ 4. 0.71/ σ A B C D a. 4 2 1 3 b. 4 1 2 3 c. 3 1 2 4 d. 3 2 1 4 Match List I with List II and select the correct answer: List I (Bridge) A. Maxwell’s bridge B. Hay’s bridge C. Schering bridge D. Wien bridge List II (Parameter to be measured) 1. Frequency 2. Inductance of medium Q-coils (1 < Q < 10) 3. Inductance of high-Q coils (Q> 10) 4. Capacitance A B C D a. 4 3 2 1 b. 4 1 2 3 c. 2 1 4 3 d. 2 3 4 1 Which of the following are the characteristics of a thermocouple type of indicating instrument?

7.

1. Its accuracy is very high, as high as about 1 percent. 2. It has a linear scale because a d’ Arsonval movement is used for measuring the output. 3. It is an RF instrument and can be used for frequency up to about 50 MHz. 4. It cannot be damaged by overloads. a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 1 and 3 Consider the following equations which can be derived from the ac bridges shown in the Figure I and Figure II by assuming ΔL/L = 0.1 and R = wL: 1. v01 = v02

9.

10.

2. v01 = 0.05vs

3. v01 = 0.1vs 4. v02 = 0.05vs 5. v02 = 0.1vs

11.

8.

The correct derived equations from these figures of ac bridges are a. 1,3 and 4 b. 2,4 and 5 c. 2 and 5 d. 1, 3 and 5 Which one of the following statements correctly represents the post acceleration in a Cathode-Ray Tube? a. It provides deflection of the beam b. It increases the brightness of the trace if the signal frequency is higher than 10 MHz c. It accelerates the beam before deflection d. It increases the brightness of the trace of low frequency signal

12.

13.

2 of 15 If the Q-factor of a coil is measured by varying the frequency, then a. The plot between Q and frequency is linear b. The value of Q initially decreases with increase of frequency and afterwards it will increase with increase of frequency c. The value of Q initially increases with increase of frequency and afterwards it will decrease with increase of frequency d. The Q-factor remains constants irrespective of value of frequency Consider the following statements: The value of earth resistance depends upon 1. Shape of electrode 2. Depth to which the electrode is driven into earth 3. Specific resistance of soil 4. Material of electrode Which of the following statements is correct? a. 1,2,3 and 4 b. 2,3 and 4 c. 1 and 2 d. 1, 3 and 4 Which of the following electronic instruments (or equipment) can be used to measure correctly the fundamental frequency component of a waveform and its higher harmonics? 1. Cathode ray oscilloscope 2. Vacuum tube voltmeter 3. Spectrum analyzer 4. Distortion factor meter Select the correct answer using the codes given below: a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 1 and 4 In a single-phase power factor meter; the controlling torque is a. Provided by spring control b. Provided by gravity control c. Provided by stiffness of suspension d. Not required Which one of the following transducers can be used for measurement of pressures as high as 100,000 atmosphere? a. Mcleod gauge b. Pirani gauge c. Bridgman gauge

14.

15.

d. Knudsen gauge A dc circuit can be represented by an internal voltage source of 50 V with an output resistance of 100 k Ω. In order to achieve accuracy better than 99% for voltage measurement across its terminals, the voltage measuring device should have a resistance of at least a. 10 MΩ b. 1 M Ω c. 10 kΩ d. 1 kΩ Consider the following blocks diagrams: 1.

18.

19.

2.

3.

4.

20.

16.

17.

Which of these block diagrams can be reduced to transfer function C (s) G1 ? = R ( s ) 1 − G1G2 a. 1 and 3 b. 2 and 4 c. 1 and 4 d. 2 and 3 In electrodynamometer type watt meters, the inductance of pressure coil produces error. The error is a. Constant irrespective of the power factor of the load b. Higher at higher power factor loads c. Higher at lower power factor loads d. Highest at unity power factor loads An analogue voltage signal whose highest significant frequency is 1 kHz is to be coded with a resolution of 0.01 percent for a voltage range of 0 – 10 V. The minimum sampling frequency and the minimum number of bits should respectively be

21.

22.

3 of 15 a. 1 kHz and 12 b. 1 kHz and 14 c. 2 kHz and 12 d. 2 kHz and 14 An ac voltmeter using full-wave rectification and having a sinusoidal input has an ac sensitivity equal to a. 1.414 times dc sensitivity b. dc sensitivity c. 0.90 times dc sensitivity d. 0.707 times dc sensitivity Consider the following statements in connection with measurement of temperature: 1. A thermistor is highly sensitive as compared with platinum resistance thermometer. 2. The resistance of a thermistor is solely a function of its absolute temperature whether the source of heat is external, internal or both. 3. A thermistor has linear resistance temperature characteristics. 4. Most thermistors exhibit negative resistance temperature coefficient. Which of these statements are correct? a. 1,2 and 3 b. 1,2 and 4 c. 2,3 and 4 d. 1,3 and 4 Time division multiplexing is used when the data to be transmitted is a. Slow changing b. Of small bandwidth c. Slow changing and has a small bandwidth d. Fast changing and has a wide bandwidth If an induction type energy meter runs fast, it can be slowed down by a. Lag adjustment b. Light load adjustment c. Adjusting the position of braking magnet and moving it closer from the centre of the disc d. Adjusting the position of braking magnet and moving it away from the centre of the disc The circuit generally used in digital instruments to convert sine waves into rectangular pulses is a a. Saw tooth generator b. Differential amplifier c. Sample and hold circuit

23.

24.

25.

26.

27.

28.

29.

d. Schmitt trigger Spectrum analyzer is a combination of a. Narrow band super heterodyne receiver and CR0 b. Signal generator and CR0 c. Oscillator and wave analyzer d. VTVM and CR0 Total number of electrons that can be accommodated in various electron states in a valence band of a given solid is equal to a. Atomic number of the solid b. Half the number of atoms in the solid c. The number of atoms in the solid d. Twice the number of atoms in the solid Consider the following properties pertaining to an alloy used as a precision resistor: 1. Uniform resistance 2. Stable resistance 3. Zero or low temperature coefficient of resistivity Which of these properties are desirable? a. 1,2 and 3 b. 1 and 2 c. 1 and 3 d. 2 and 3 By inserting a slab of dielectric material between the plates of a parallel plate capacitor, the energy stored in the. capacitor has increased three times. The dielectric constant of the material is a. 9 b. 3 c. 1/3 d. 1/9 When a dielectric is subjected to an alternating electric field, of angular frequency ‘ ω ’, its power loss is proportional to a. ω b. ω 2 c. 1/ ω d. 1/ ω 2 For a given dielectric, with increase in temperature the ionic polarizability a. Increases b. Decreases c. Remains same d. Fluctuates A piezoelectric crystal has an Young’s modulus of 130 GPa. The uniaxial stress that must be applied to increase its polarization from 500 to 510 C m-2 is

30.

31.

32.

33.

34.

35.

36.

4 of 15 a. 1.171GPa b. 1.182GPa c. 2.6 GPa d. 2.55 GPa When temperature bf a conductor is approaching zero Kelvin, the mean free path of the free electrons in the conductor is proportional to a. T b. T3 c. (1/T)1/3 d. 1/T3 In a conductor of size 20 mm × 10 mm × 10 mm, the wavelength of the slowest moving free electron is a. 5 mm b. l0 mm c. 20 mm d. 40 mm The conductivity of a conducting material on being subject to critical magnetic field changes to a. Normal state b. Unstable state c. Temperature-independent state d. Temperature-dependent state A large value of the exchange interaction energy in a ferromagnetic material implies a. Large saturation magnetization b. High Curie temperature c. High melting point d. Large diamagnetic susceptibility Which one of the following pairs is NOT correctly matched? a. Copper : Diamagnetic b. Sodium : Anti ferromagnetic c. Iron : Ferromagnetic d. Ferrite : Ferromagnetic Ferromagnetic behavior is shown by those transition meals where the ratio of the atomic diameter to 3d orbital diameter is a. In the range of 0.5 to 1 b. In the range of 1 to 1.5 c. In the range of 1.5 to 2 d. Greater than 2 Ferrites can be considered as mixed oxides of metals A and B having inverse spinel structure. Their formula can be written as a. ABO2 b. A2BO2 c. AB2O3 d. AB2O4

37.

38.

39.

40.

Match List I (Magnetic materials) with List 11 (Main applications) and select the correct answer: List I A. Ni-Zn ferrite B. Co-Sm alloy C. Yttrium Iron Garnet D. Mg-Zn ferrite List II 1. Recording head 2. Permanent Magnets 3. Audio & TV transformers 4. Memory cores 5. Microwave isolators A B C D a. 3 4 5 2 b. 1 2 3 4 c. 3 2 5 4 d. 1 4 3 2 For a semiconductor, which one of the following statements is NOT correct? a. When an electron and a hole recombine, energy must be liberated b. Electrons in the conduction band can acquire a net acceleration from a field because there are empty energy levels available c. An electron in the valence band cannot be accelerated by the field unless there are empty energy levels available d. Holes cannot be accelerated by the field unless there are empty energy levels available Consider the following statement: Extrinsic semiconductors show high electrical conductivity because the impurities are 1. Of high conductivity 2. Highly mobile 3. Highly charged Which of these statements are NOT correct? a. 1 and 2 b. 2 and 3 c. 1 and 3 d. 1,2 and 3 Match List I with List II and select the correct answer: List I A. Ga-As B. Nichrome C. Quartz D. Si List II

5 of 15 Integrated Circuit Laser Busbar Heating element Oscillator A B C D a. 2 4 5 1 b. 1 5 3 2 c. 2 5 3 1 d. 1 4 5 2 Consider the following energy-momentum (E-k) curves labelled as 1, 2, 3 and 4 of different semiconductors: 1. 1. 2. 3. 4. 5.

41.

2.

3.

4.

42.

Sets of direct and indirect gap curves are respectively a. (1, 2) and (3, 4) b. (1, 4) and (2,3) c. (1, 3) and (2, 4) d. (2, 3) and (1,4) Match List I (p - n junction devices) with List II (Application) and select the correct answer: List I

43.

44.

45.

A. Zener Diode B. Pin Diode C. Tunnel Diode D. Varactor Diode List II 1. Fast-switching circuits 2. Microwave switches 3. Local oscillators for radars 4. Frequency converters 5. Voltage regulators A B C D a. 5 2 1 4 b. 1 2 5 4 c. 5 3 1 2 d. 1 3 5 2 The open circuit impedance of a certain length of a lossless line is 100Ω. The short circuit impedance of the same line is also 100Ω. The characteristic impedance of the line is a. 100 2Ω b. 50 Ω c. 100 / 2Ω d. 100 Ω Assertion (A): The relationship between Magnetic Vector potential A and the Current density J in free space is ∇ × ( ∇ × A ) = μ0 J . For a magnetic field in free space due to a dc or slowly varying current is ∇ 2 A = − μ0 J Reason (R): For magnetic field due to dc or slowly varying current ∇. A = 0 . a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true ∂D Given that ∇ × H = J + ∂t Assertion (A): In the equation, the ∂D is necessary. additional term ∂t Reason (R): The equation will be consistent with the principle of conservation of charge. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false

46.

47.

48.

49.

6 of 15 d. A is false but R is true Assertion (A): When there is no charge in the interior of a conductor the electric field intensity is infinite. Reason (R): As per Gauss’s law the total outward electric flux through any closed surface constituted inside the conductor must vanish. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The solution to the wave equation at the critical diffracting condition in a crystal yields standing waves. Reason (R): Standing waves have periodic variation both in amplitude as well as in the electron probability density in the crystal. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): For a system to be stable, all coefficients of the characteristic polynomial must be positive. Reason(R): All positive coefficients of the characteristic polynomial of a system is a sufficient condition for stability. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true In the feedback system C(s), R(s) and D(s) are the system output, input and disturbance, respectively

Assertion (A): For the system C ( s ) { R ( s ) + D ( s )} 1+ G (s) = R (s) D (s) 1+ G (s) H (s) Reason (R): Transfer function of a system is defined as the ratio of output Lap lace transform and input Lap lace transform

50.

51.

52.

53.

setting other inputs and the initial conditions to zero. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The number of separate loci of the closed loop system corresponding to K ( s + 4) is three. G (s) H (s) = s ( s + 1)( s + 3) Reason (R) : Number of separate loci is equal to number of finite poles of G(s) H(s) if the latter is more than the number of finite zeros of G(s) H(s). a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The current in a constant inductive system does not change instantaneously. Reason (R): In constant inductive system the flux linkage is conserved initially. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Equivalent network obtained from Δ − Y transformation relationships in general is valid only for one frequency. Reason (R): The impedances involved in Δ − Y vary with frequency. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Norton theorem is applied to a network for which no equivalent Thevenin’s network exists. Reason (R): Norton’s Theorem enables one to calculate quickly current and voltage in a particular branch of interest in a complicated network.

54.

55.

56.

57.

7 of 15 a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): A unit current impulse applied to a capacitor of ‘C’ farads instantly inserts 1/2C Joules of energy in it. Reason (R): A unit current impulse has infinite current for zero duration and encloses a charge of one coulomb in it. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): In resistance potentiometers used for measurement of displacement, sensitivity and linearity are conflicting requirements. Reason (R): The voltmeter used for measurement of output voltage of the potentiometer has, a finite resistance which causes loading effects. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): In good quality magnetic cassette tape recorders, ac bias is provided to recording head for better recording and reproduction. Reason (R): The use of ac bias avoids the nonlinear characteristic of the B-H curve of the recording head. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): In digital transducers used for measurement of displacement, it is quite common to use Gray Code instead of natural binary code. Reason (R): Grey code is used for overcoming the inherent disadvantages of a natural binary code. These include errors that are caused on account of even slight

8 of 15

58.

misalignment which may cause change of decimal number thereby changing the number of bits. Gray code does not sufer from this disadvantage. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true If A = aˆr + aˆφ + aˆ z , the value of ∫ A.dl

d.

60.

around the closed circular quadrants shown in the given figure is

A point charge +Q is brought near a corner of two right angle conducting planes which are at zero potential as shown in the given Figure I. Which one of the following configurations describes the total effect of the charges for calculating the actual field in the first quadrant?

a. a. π

b.

π 2

+4

c. π + 4

59.

π

+2 2 A coaxial cable has two concentric dielectrics separated by a sheath as shown in the given figure. The distribution of electric field ‘E’ and potential ‘ φ ’ in the coaxial’ cable exist as

d.

b.

c. a.

d.

b.

c. 61.

Plane defined by z = 0 carry surface current density 2aˆ x A / m . The magnetic intensity ‘Hy’ in the two regions −α < z < 0 and 0 < z < α are respectively

9 of 15 a. aˆ y and – aˆ y

b. – aˆ y and aˆ y

62.

63.

c. aˆ x and – aˆ x d. – aˆ x and aˆ x A solid cylindrical conductor of radius ‘R’ carrying a current ‘I’ has a uniform current density. The magnetic field intensity ' H ' inside the conductor at the radial distance ‘r’ (r < R) is a. Zero b. I / 2π r c. Ir / 2π R 2 d. IR 2 / 2π r 3 The electric field across a dielectric-air interface is shown in the given figure. The surface charge density on the interface is

a. −4 ∈0 b. −3 ∈0

3.

4.

66.

c. −2 ∈0 64.

65.

d. − ∈0 When air pocket is trapped inside a dielectric of relative permittivity ‘5’, for a given applied voltage across the dielectric, the ratio of stress in the air pocket to that in the dielectric is equal to a. 1/5 b. 5 c. 1+5 d. 5-1 Consider coils C1, C2, C3 and.C4 (shown in the following figures) which are placed in the time-varying electric field E ( t ) and electric field produced by the coils C’2, C’3 and C’4 carrying time varying current I(t) respectively: 1.

67.

The electric field will induce an emf in the coils a. C1 and C2 b. C2 and C3 c. C1 and C3 d. C2 and C4 A circular loop is rotating about the y-axis as a diameter in a magnetic field B = B0 sin ωt aˆ x Wb / m 2 . The induced emf in the loop is a. Due to transformer emf only b. Due to motional emf only c. Due to a combination of transformer and motional emf d. Zero Match List I with List II and select the correct answer: List I (Law/quantity) A. Gauss’s law B. Ampere’s law C. Faraday’s law D. Poynting vector List II (Mathematical expression) 1. ∇.D = ρ ∂B 2. ∇ × E = − ∂t 3. S = E × H

(

4. F = q E + v × B 5. ∇ × H = J c +

2.

a. b.

A 1 3

B 2 5

)

∂D ∂t C 4 2

D 3 1

c. d.

68.

69.

1 3

5 2

2 3 4 1 1+ | Γ | ; the values of S In the relation S = 1− | Γ | and Γ (Where S stands for wave ratio and Γ is reflection coefficient), respectively, very as a. 1 to 1 and –1 to 0 b. 1 to ∝ and –1 to +1 c. –1 to +1 and 1 to ∝ d. –1 to 0 and 0 to 1 In the source free wave equation ∂2 E ∂E ∇ 2 E − μ0 ∈0 μ ∈ 2 − μ0 μ σ =0 ∂t ∂t The term responsible for the attenuation of the wave is ∂E a. μ0 μσ ∂t ∂2 E b. μ0 ∈0 μ ∈ 2 ∂t c. ∇ 2 E

73.

74.

∂E ∂2E and μ0 ∈0 μ0∈ 2 ∂t ∂t Three media are characterized by 1. ∈r = 8, μ r = 2, σ = 0 d. μ0 μσ

70.

2. ∈r = 1, μr = 9, σ = 0 3. ∈r = 4, μr = 4, σ = 0

71.

∈r is relative permittivity, μ r is relative permeability and σ is conductivity. The value of the intrinsic impedances of the media 1,2 and 3 respectively are a. 188 Ω, 377Ω and 1131Ω b. 377Ω, 113Ω and l88Ω c. 188Ω, 1131Ω and 377Ω d. 1131Ω , 188Ω and 377Ω A plane em wave E i H i traveling in a

(

75.

)

b. exp ( 5s )

perfect dielectric medium of surge impedance ‘Z’ strikes 2Z. If the refracted em wave is E r H r , the ratios of E1 / Er

(

72.

)

and Ei / H r are respectively a. 1/3 and 3/2. b. 3/2 and 1/3 c. 3/4 and 3/2 d. 3/4 and 2/3 For a perfect conductor, the field strength at a distance equal to the skin depth is X% of the field strength at its surface. The value ‘X%’ is

10 of 15 a. Zeno b. 50% c. 36% d. 26% Consider the following statements: The characteristic impedance of a transmission line can increase with the increase in 1. Resistance per unit length 2. Conductance per unit length 3. Capacitance per unit length 4. Inductance per unit length Which of these statements are correct? a. 1 and 2 b. 2 and 3 c. 1 and 4 d. 3 and 4 Match List I (Physical action or activity) with List II (Category of system) and select the correct answer: List I A. Human respiration system B. Pointing of an object with a finger C. A man driving a car D. A thermostatically controlled room heater List II 1. Man-made control system 2. Natural including biological control system 3. Control system whose components are both manmade and natural A B C D 2 2 3 1 a. 3 1 2 1 b. 3 2 2 3 c. 2 1 3 3 d. The Lap lace transform of a transportation lag of 5 seconds is a. exp ( −5s ) 1 s+5 ⎛ −s ⎞ d. exp ⎜ ⎟ ⎝ 5 ⎠ In the system shown in the given figure r ( t ) = 1 + 2t ( t ≥ 0 ) . The steady-state value

c.

76.

of the error e(t) is equal to

a. Zero

77.

78.

b. 2/10 c. 10/2 d. Infinity The phase angle of the system s+5 varies between G (s) = 2 s + 4s + 9 a. 0° and 90° b. 0° and –90° c. 0° and –180° d. –90° and –180° The transfer function of a certain system is s given by G ( s ) = (1 + s )

81.

11 of 15 c. Non-zero number d. Constant The Nyquist plot of a servo system is shown in the Figure I. The root loci for the system would be

The Nyquist plot of the system is a.

a.

b.

b.

c.

c.

d.

79.

80.

A second order control system is defined by the following differential equation: d 2c ( t ) dc ( t ) 4 +8 + 16c ( t ) = 16u ( t ) 2 dt dt The damping ratio and natural frequency for this system are respectively a. 0.25 and 2 rad/s b. 0.50 and 2 rad/s c. 0.25 and 4 rad/s d. 0.50 and 4 rad/s The steady state en-or due to a ramp input for a type two system is equal to a. Zero b. Infinite

82.

d. None of the drawn plot of (a), (b), (c) of the question The characteristic equation of a feedback control system given by 3 2 s + 5s + ( K + 6 ) s + K = 0 .In the root loci

83.

diagram, the asymptotes of the root loci for large ‘K’ meet at a point in the s-plane whose coordinates are a. (2, 0) b. (–1, 0) c. (–2, 0) d. (–3, 0) The open loop transfer function of a unity K . If feedback system is given by s ( s + 1) the value of gain K is such that the system is critically damped, the closed loop poles of the system will lie at a. – 0.5 and 0.5

84.

85.

86.

b. ± j0.5 c. 0 and –1 d. 0.5 ± j 0.5 If the Nyquist plot cuts the negative real axis at a distance of 0.4, then the gain margin of the system is a. 0.4 b. – 0.4 c. 4% d. 2.5 The transfer function of a phase lead 1 + aTs where compensator is given by 1 + Ts a > 1 and T > 0. The maximum phase shift provided by such a compensator is ⎛ a +1⎞ a. tan −1 ⎜ ⎟ ⎝ a −1 ⎠ ⎛ a −1 ⎞ b. tan −1 ⎜ ⎟ ⎝ a +1 ⎠ ⎛ a +1⎞ c. sin −1 ⎜ ⎟ ⎝ a −1 ⎠ ⎛ a −1 ⎞ d. sin −1 ⎜ ⎟ ⎝ a +1 ⎠ Consider the single input, single output system with its state variable representation: ⎡ −1 0 0 ⎤ ⎡1 ⎤ ⎢ ⎥ X = ⎢ 0 −2 0 ⎥ X + ⎢⎢1 ⎥⎥ U ⎣⎢ 0 0 −3⎦⎥ ⎣⎢0 ⎦⎥

Y = [1 0 2] X

87.

The system is a. Neither controllable nor observable b. Controllable but not observable c. Uncontrollable but observable d. Both controllable and observable A particular control system is described by the following state equations: ⎡0 1⎤ ⎡0 ⎤ X =⎢ X + ⎢ ⎥ U and Y = [ 2 0] X ⎥ ⎣ −2 −3⎦ ⎣1 ⎦ The transfer function of this system is: Y (s) 1 = 2 a. U ( s ) 2s + 3s + 1

b. c.

88.

The system is described as

d 2 y1 ( t ) dy ( t ) +B 1 = k ⎡⎣ y2 ( t ) − y1 ( t ) ⎤⎦ 2 dt dt d 2 y2 ( t ) dy ( t ) M +B 2 = k ⎡⎣ y2 ( t ) − y1 ( t ) ⎤⎦ 2 dt dt d 2 y1 ( t ) dy ( t ) M +B 1 = k ⎡⎣ y1 ( t ) − y2 ( t ) ⎤⎦ 2 dt dt d 2 y2 ( t ) dy ( t ) M +B 2 = k ⎡⎣ y1 ( t ) − y2 ( t ) ⎤⎦ 2 dt dt

a. M b. c. d. 89.

A linear time invariant system, initially at rest when subjected to a unit step input gave response. c ( t ) = te − t ( t ≥ 0 ) . The transfer function of the system is s a. 2 ( s + 1) b. c. d.

90.

91.

Y (s) 2 = 2 U ( s ) 2s + 3s + 1 Y (s) 1 = 2 U ( s ) s + 3s + 2

12 of 15 Y (s) 2 = d. U ( s ) s 2 + 3s + 2 The mechanical system is shown in the given figure

92.

1 s ( s + 1)

2

1

( s + 1)

2

1 s ( s + 1)

A synchro transmitter consists of a a. Salient pole rotor winding excited by an ac supply and a three-phase balanced stator winding b. Three-phase balance stator winding excited by a three- phase balanced ac signal and rotor connected to a dc voltage source c. Salient pole rotor winding excited by a dc signal d. Cylindrical rotor winding and a stepped stator excited by pulses The torque-speed characteristic .of twophase induction motor is largely affected by a. Voltage b. R/X and speed c. X/R d. Supply voltage frequency Match List I (Nature of eigen value) with List II (Nature of singular point) for

13 of 15

93.

94.

95.

96.

linearised autonomous second order system and select the correct answer: List I A. Complex conjugate pair B. Pure imaginary pair C. Real and equal but with opposite sign D. Real, distinct and negative List II 1. Centre 2. Focus point 3. Saddle point 4. Stable node 5. Unstable node A B C D a. 1 5 3 4 b. 2 1 3 4 c. 2 1 4 3 d. 1 5 4 3 In order to use Routh Hurwitz Criterion for determining the stability of sampled data system, the characteristic equation 1 + G(z) H(z) = 0 should be modified by using bilinear trans form of a. z = r + 1 b. z = r − 1 r −1 c. z = r +1 r +1 d. z = r −1 The system matrix of a discrete system is given by ⎡0 1⎤ A=⎢ ⎥ ⎣ −3 −5⎦ The characteristic equation is given by a. Z2 + 5z + 3 = 0 b. Z2 – 3z – 5 = 0 c. Z2 + 3z + 5 = 0 d. Z2 + z + 2 = 0 The current in the given circuit with a dependent voltage source is

a. 10A b. 12A c. 14 A d. 16A The value of resistance ‘R’ shown in the given figure is

97.

98.

99.

100.

101.

a. 3.5Ω b. 2.5Ω c. 1Ω d. 4.5Ω An electric circuit with 10 branches and 7 nodes will have a. 3 loop equations b. 4 loop equations c. 7 loop equations d. 10 loop equations For the circuit shown in the given figure, the current through L and the voltage across C2 are respectively

a. zero and RI b. I and zero c. zero and zero d. I and RI For the circuit shown in the given figure, when the voltage E is 10 V, the current i is 1 A. If the applied voltage across terminal C-D is 100 V, the short circuit current flowing through the terminal A-B will be

a. 0.1A b. 1A c. 10A d. 100A The Thevenin’s equivalent resistance Rth for the given network is

a. 1Ω b. 2Ω c. 4Ω d. Infinity For the circuit shown in the given figure the current I is given by

14 of 15 d 2i / dt 2 + i = v . If v = Ae2t , the dominant solution of I for t > 0 is of the nature. a. K1et

102.

103.

104.

105.

a. 3A b. 2A c. 1A d. Zero The value of V in the circuit shown in the given figure is

a. 1 V b. 2 V c. 3 V d. 4 V The Norton’s equivalent of circuit shown in Figure I is drawn in the circuit shown in Figure II. The values of ‘ISc and Req in Figure II are respectively

a. 5/2 A and 2 Ω b. 2/5 A and 1 Ω c. 4/5 A and 12/5Ω d. 2/5 A and 2Ω A pole of driving point admittance function implies a. Zero current for a finite value of driving voltage b. Zero voltage for a finite value of driving current c. An open circuit condition d. None of (a), (b) and (c) mentioned in the question The driving point function of the circuit shown in the given figure when s→0 and s→∞, (the elements are normalized) will respectively be

b. K1e −t c. K1e 2t 107.

The current i is given by a. 1 − e− t b. ⎡⎣1 − e −(t −5) ⎤⎦ u ( t − 5 ) c. (1 − e− t ) u ( t − 5 )

108.

109.

110.

106.

a. 1/s and 2/s b. 1/s and 0.75 c. 0.75 and 2/s d. 2/sand 0.75 The response I of a network is expressed by the differential equation

d. K 2 cos t + K 3 sin t A unit step u(t–5) is applied to the RL network

d. 1 − e −(t −5) The response of an initially relaxed system to a unit ramp excitation is ( t + e −t ) . Its step response will be a. 1/ 2t 2 − e −t b. 1 − e− t c. −e −t d. t Two current wave forms as shown in the figure I and figure II, are passed through identical resistors of 1Ω. The ratio of heat produced in these resistors in a given time by current of Figure I to Figure II is

a. 2 : 1 b. 1 : 2 c. 1 : 1 d. 1: 2 The response of a network is i ( t ) = K t e −α t for t ≥ 0 where α is real positive. The value of ‘t’ at which the i(t) will become maximum, is a. α b. 2 α c. 1/ α d. α 2

15 of 15 111.

112.

Cauer and Foster forms of realizations are used only for a. Driving point reactance functions b. Transfer reactance functions v c. Driving point impedance functions d. Transfer impedance functions For the given driving point impedance 4s 4 + 7 s 2 + 1 function Z ( s ) = , the circuit s ( 2 s 2 + 3)

a. b. c. d. 117.

realization is shown in the given figure. Then the values of L and C are respectively

113.

114.

115.

a. 0.5 and 5 b. 2 and 1 c. 4 and 1 d. 4 and 3 The h parameters h11 and h22 are related to z and y parameters as a. h11 = z11 and h22 = 1/z22 b. h11 = z11 and h22 = y22 c. h11 = 1/y11 and h22 = 1/z22 d. h11 = 1/y11 and h22 = y22 The driving point impedance s+2 Z (s) = . The system is initially at s+3 rest. For a voltage signal of unit step, the current i(t) through the impedance Z is given by a. 2 − e −t b. 3 / 2 − 1/ 2e−3t c. 3 / 2 − 1/ 2e−2t d. 3 − 2e −3t If i = −10e −2t , the voltage of the source of the given circuit, Vs is given by

118.

119.

116.

1 . For an s +1 signal cos t, the steady state response is ⎛ π⎞ a. 1/ 2 cos ⎜ t − ⎟ ⎝ 4⎠ b. cos t ⎛ π⎞ c. cos ⎜ t − ⎟ ⎝ 4⎠ d. 1/ 2 cos t The value of the capacitance ‘C’ in the given ac circuit to make it a constant resistance circuit OR for the supply current to be independent of its frequency is The system function H ( s ) =

a. 1/16 F b. 1/12 F c. 1/8 F d. 1/4 F The resonant frequency of the given series circuit is

a. 1/ 2π 3Hz b. 1/ 4π 3Hz

120.

a. −10e −2t b. −20e −2t c. 20e −2t d. −30e −2t The steady state in the circuit, shown in the given figure is reached with S open. S is closed at t = 0. The current I at t = 0+ is

1A 2A 3A 4A.

c. 1/ 4π 2Hz d. 1/ π 2 Hz The transfer function V2 ( s ) 10s = 2 is for an active V1 ( s ) s + 10s + 100 a. Low pass filter b. Band pass filter c. High pass filter d. All pass filter

I.E.S (OBJ) - 2002

1 of 16

ELECTRICAL ENGINEERING PAPER–I 1.

2.

3.

4.

5.

A potential field is given by V = 3x2y – yz. Which of the following is NOT true? a. At the point (1, 0, -1), V and the electric field E vanish b. x 2 y = 1 is an equipotential line in the xy-lane c. The equipotential surface V – 8 passes through the point P(2, -1, 4) d. A unit normal to the equipotential surface V = -8 at P is ( −0.83xˆ + 0.55 yˆ + 0.07 zˆ )

6.

7.

The relation between electric intensity E, voltage applied V and the distance d between the plates of a parallel plate condenser is a. E = V/d b. E = V × d c. E = V/(d)2 d. E = V × (d)2 Ohm’s law in point form in field theory can be expressed as a. V = RI b. J = E / σ c. J = σ E d. R = ρ l / A The magnetic flux through each turn of a 100 turn coil is (t3 - 2t) milli-Webers where t is in seconds. The induced e.m.f. at t = 2s is a. 1V b. -1V c. 0.4 V d. -0.4 V If a vector field B is solenoidal, which of these is true? a.

L

b.

S

∫ B.dl = 0 ∫ B.ds = 0

c. ∇ × B = 0 d. ∇.B ≠ 0

A medium behaves like dielectric when the a. displacement current is just equal to the conduction current b. displacement current is less than the conduction current c. displacement current is much greater than the conduction current d. displacement current is almost negligible Two conducting coils 1 and 2 (identical except that 2 is split) are placed in a uniform magnetic field which decreases at a constant rate as in the figure. If the planes of the coils are perpendicular to the field lines, the following statements are made:

an e.m.f. is induced in, the split coil 2 e.m.f. is are induced in both coils equal Joule heating occurs in both coils Joule heating does not occur in any coil Which of the above statements is/are true? a. 1 and 4 b. 2 and 4 c. 3 only d. 2 only For linear isotropic materials, both E and H have the time dependence e jωt and regions of interest are free of charge. The value of ∇ × H is given by

1. 2. 3. 4.

8.

a. σ E b. jωε E c. σ E + jωε E d. σ E − jωε E

9.

10.

Which of the following equations is/are not Maxwell’s equation(s)? ∂lv 1. ∇.J = − ∂t 2. ∇.D = lv ∂B 3. ∇.E = − ∂t ⎛ ∂E ⎞ 4. ∫ H .dl = ∫ ⎜⎝ σ E + ε ∂t ⎟⎠.ds

12.

Select the correct answer using the codes given below: a. 2 and 4 b. 1 alone c. 1 and 3 d. 1 and 4 In free space 7 H ( z , t ) = 0.10 cos ( 4 × 10 t − β z ) Tx A/M. The expression for E ( z , t ) is a. E ( z, t ) = 37.7 cos ( 4 ×107 t − β z ) Ty

b. E ( z, t ) = 2.65 ×10 cos ( 4 ×107 t − β z ) Tz c. E ( z, t ) = 37.7 cos ( 4 ×107 t − β z ) Tx d. E ( z, t ) = −37.7 cos ( 4 ×107 t − β z ) Ty

13.

11.

Consider the arrangement of two equal and opposite charges of magnitude q separated by an infinitesimal distance 1 as shown in the figure given above. If ar is the unit vector in the direction r and aθ is the unit vector in the directionθ, the electric field at the point P is −2q / cos θ q / sin θ ar − aθ a. 3 4πε r 4πε r 3 −2q / cos θ q / sin θ ar + aθ b. 3 4πε r 4πε r 3 2q / cos θ q / sin θ ar + aθ c. 3 4πε r 4πε r 3 2q / cos θ q / sin θ ar − aθ d. 3 4πε r 4πε r 3

14.

15.

2 of 16 A plane wave whose electric field is given by E = 100 cos(ωt - 6π x ) zˆ passes normally from a material ‘A’ having ε r = 4, μr = 1 and σ = 0 to a material ‘B’ having ε r = 9 , μr = 4 and σ = 0 . Match items in List I with List II and select the correct answer: List I A. Intrinsic impedance of medium ‘B’ B. Reflection coefficient C. Transmission Coefficient D. Phase shift constant of medium ‘A’ List II 1. 6 π 2. 80 π 3. 1/7 4. 8/7 Codes; A B C D a. 4 1 2 3 2 3 4 1 b. c. 4 3 2 1 d. 2 1 4 3 In free space E ( z, t ) = 50 cos (ωt − β z ) ax A/m and H ( z , t ) = 5 /12π cos (ωt − β z ) a y

A/m. The average power crossing a circular area of radius 24 m in plane z = constant is a. 200 W b. 250 W c. 300 W d. 350 W A copper wire carries a conduction current of 1.0 A at 50 Hz. For copper wire ε = ε 0 , μ = μ0 , σ = 5.8 ×10 mho/m. What is the displacement current in the wire? a. 2.8 × 10 A b. 4.8 × 10 A c. 1 A d. It cannot be calculated with the given data If A and J are the vector potential and current density vectors associated with a coil, then

∫

A.Jdv has the units of

a. Flux-linkage b. Power c. Energy

16.

d. Inductance A transmission line has R, L G and C distributed paramenters per unit length of the line, γ is the propagation constant of the lines. Which expression gives the characteristic impedance of the line? a. b. c. d.

17.

20.

γ R + jωl

21.

R + jωl

γ G + jωC

γ G + jωC R + jω L

Which of the following equations is correct? a. ax × ax = ax b.

(a

x

2

× a y ) + ( a y × ax ) = 0

c. ax × ( a y × az ) = ax × ( az × a y ) d. ar .aθ + aθ .ar = 0 18.

Match List I with List II and select the correct answer: List I (Term) A. Curl ( F ) = 0 B. Div ( F ) = 0

19.

C. Div Grad (φ) = 0 D. Div div (φ) = 0 List II (Type) 1. Laplace equation 2. Irrotational 3. Solenoidal 4. Not defined A B C D a. 2 3 1 4 b. 4 1 3 2 c. 2 1 3 4 d. 4 3 1 2 Assuming the Fermi level EF to be independent of temperature, EF may be defined as the level with an occupancy probability of a. 0% b. 50% c. 75%

22.

3 of 16 d. 100% Which of the following has the greatest mobility? a. Positive ion b. Negative ion c. Electron d. Hole Match List I (Type of the material) with List II (Name of thfe material) and select the correct answer: List I A. Ferroelectric material B. Piezoelectric material C. Soft magnetic material D. Hard magnetic material List II 1. Permalloy 2. BaTiO3 ceramic 3. KH2PO4 4. Tungsten steel Codes; A B C D a. 3 2 1 4 b. 1 4 3 2 c. 3 4 1 2 1 2 3 4 d. On the application of the field E , the modified field due to polarization P in solids and liquids having cubic symmetry is given by P a. E +

ε0

b. E −

23.

P

ε0

c. E +

P 3ε 0

d. E −

P 3ε 0

The complex dielectric constant of a material is given by the expression : ε = ε '− jε " If a parallel plate capacitor with area ‘A’ and separation‘d’ is formed with this material as a dielectric, the loss factor will be a. ( Aε ') / ( d ε ") b. ε "/ ε '

c. tan ⎡⎣( Aε ') / ( d ε ") ⎤⎦ −1

24.

25.

26.

27.

28.

29.

30.

d. tan −1 ⎡⎣( Aε ") / ( Aε ') ⎤⎦ At optical frequencies, the major contribution to the total polarization comes from a. space charge polarization b. orientation polarization c. ionic polarization d. electronic polarization Which of the following insulating materials has the least affinity for moisture? a. Cotton b. Paper c. Asbestos d. Mica Which of the following statements is NOT true? a. Superconductors show perfect diamagnetism b. Superconductors have almost zero resistivity c. The external magnetic field has no effect on superconductors d. Entropy increases on going from superconducting state to normal state The transition temperature of Mercury at which it becomes superconductive is a. 4.12°F b. 4.12°C c. 4.12 K d. 41.2 K de Brogue wavelength associated with a material particle is a. inversely proportional to its energy b. directly proportional to its momentum c. directly proportional to its energy d. inversely proportional to its momentum Which one of the following materials can not be used for permanent magnets? a. Alnico b. Barium Ferrite c. Carbon-steel d. Iron-Cobalt alloy Upto about 4% silica is added in iron to be used as a soft magnetic material. The major reason for this is to

31.

4 of 16 a. increase permeability of the material b. increase electrical resistivity of the material c. increase the coercive force d. increase the saturation flux density Which of the following is piezoelectric material? a. Quartz b. Silica sand c. Corundum d. Polystyrene

32.

33.

The resistance seen from the terminals A and B of the device whose characteristic is shown in the figure is a. – 5 Ω b. – 1/5 Ω c. 1/5 Ω d. 5 Ω The Fig. 1 shows a network, in which the diode is an ideal one.

the terminal v – I characteristics of the network is given by a.

b.

c.

37.

d.

5 of 16 Superposition theorem is hot applicable for a. voltage calculation b. bilateral elements c. power calculations d. passive elements

38.

For the circuit given in figure above the power delivered by the 2 volt source is given by a. 4 W b. 2 W c. – 2 W d. – 4 W

34.

The current through 120 ohm resistor in the circuit shown in the figure is a. 1 A b. 2 A c. 3 A d. 4 A

39.

The (y) parameters of the network given in Fig. 1 are given by ⎡ R −1 R1−1 ⎤ a. ⎢ 1−1 ⎥ R1−1 ⎦ ⎣ R1

35.

⎡ 0 b. ⎢ −1 ⎣ R1

36.

The v-i characteristic of an element is shown in the figure given above. The element is a. non-linear, active, non-bilateral b. linear, active, non-bilateral c. non-linear, passive, non-bilateral d. non-linear, active, bilateral If the combined generator and. line impedance is (5 + j10) ohm, then for the maximum power transfer to a load impedance from a generator of constant generated voltage, the load impedance is given by which, one of the following a. (5 + j 10) Ω b. (5 - j 10) Ω c. (5 + j 5) Ω d. 5 Ω

R1−1 ⎤ ⎥ R1−1 ⎦

⎡ R −1 0 ⎤ c. ⎢ 1 ⎥ ⎣ 0 0⎦

40.

⎡ R1−1 0 ⎤ d. ⎢ −1 ⎥ ⎣ R1 0 ⎦ The impulse response of an LTI system is given by 5u (t). If the input to the system is given by ε-t then the output of the system is given by

a. 5 (1 − ε −1 ) u ( t ) b.

(1 − 5ε ) u ( t ) −1

c. 1 − 5ε −1u ( t ) d. 5u ( t ) − ε −1 41.

6 of 16

42.

43.

For the circuit shown in the given figure, if C = 20 μF, v(0-) = - 50 V and dv (0-)/dt = 500 V/S, then R is a. 5 K b. 3 K c. 5 K d. 10 K In the circuit shown in the given figure, the switch is closed at t = 0.

The current through the capacitor will decrease exponentially with a time constant a. 0.5 s b. 1 s c. 2 s d. 10 s In the circuit shown in the given figure, the switch is moved from position A to B at time t = 0. The current i through the inductor satisfies the following conditions i(0) = - 8 A, di/dt (t = 0) = 3 A/s, i(∞) = 4 A.

The value of R is a. 0.5 ohm b. 2 ohm c. 4 ohm d. 12 ohm In the given RC circuit, the current i(t) =2 44. cos 5000 t A.

45.

46.

47.

The applied voltage v(t) is a. 28.28 cos (5000 t — 45°) V b. 28.28 cos (5000 t + 45°) V c. 28.28 sin (5000 t — 45°) V d. 28.28 sin (5000 t + 45°) V In the circuit shown in the given figure,

The current through the inductor L is a. 0 A b. 3 A c. 4 A d. 8 A A parallel circuit consists of two branches. One branch has RL and L connected in series and the other branch has RC and C connected in series. Consider the following statements: 1. The two branch currents will be in quadrature if RL RC = L/C 2. The impedance of the whole circuit is independent of frequency, if RL = RC and ω = 1/ LC 3. The circuit is in resonance for all the frequencies if RL = RC a. The two branch currents will be n phase at ω = 1/ LC Which of the above statements are correct? b. 1 and 2 c. 2 and 3 d. 1 and 3 e. 3 and 4 Three currents i1, i2 and i3 are approaching a node. If i1 = 10sin ( 400t + 60° ) A , and i2 = 10sin ( 400t − 60° ) A then i3 is

a. 0 b. 10 ( sin 400t ) A c. −10 ( sin 400t ) A

d. −5 3 ( 3sin 400t ) A 48.

52.

At resonant frequency a R-L-C series circuit draws maximum current due to the reason that a. the difference between capacitance reactance and inductance reactance is zero b. the impedance is more than the resistance c. the voltage across the capacitor equals the applied voltage d. the power factor is less than unity

7 of 16 The inductance matrix of a system of two mutually coupled inductors shown in Fig. ⎡ 5 −4 ⎤ 1 is given by L = ⎢ ⎥ ⎣ −4 7 ⎦

49.

50.

51.

In the given circuit, at resonance, IR in Amperes is equal to a. 0 b. 10 c. 5 d. 0.5 Consider the following statements about the quality factor of a R - L - C circuit: 1. For the critically damped circuit, the quality factor Q = ½ 2. Higher the value of quality factor higher will be the bandwidth of the circuit 3. Higher the value of quality factor lower will be the bandwidth of the circuit 4. For under damped circuits the value of Q is greater than ½ Which of these statements are correct? a. 1 and 2 b. 1 and 3 c. 2 and 4 d. 1, 3 and 4 When two - Wattmeter method of measurement of power is used to measure power in a balanced three phase circuit; if the Wattmeter reading is zero, then a. power consumed in the circuit is zero b. power factor of the circuit is zero c. power factor is unity d. power factor is 0.5

53.

54.

55.

When the inductors are connected as shown in Fug 2 the equivalent inductance of the system is given by a. 20 H b. 4 H c. 16 H d. 8 H Consider the following statements about the D’Arsonval Movement : 1. It is best suited for d.c. current measurement 2. It responds to the average value of current 3. It measures the r.m.s. value of a.c. currents 4. It could he used for power measurements Which of these statements is/are correct? a. Only 1 b. 1 and 2 c. 2 and 3 d. 1, 2, 3 and 4 Two meters X and Y require 40 mA and 50 mA, respectively, to give full-scale deflection, then a. sensitivity can not be judged with given information b. both are equally sensitive c. X is more sensitive d. Y is more sensitive What is the correct sequence of the following types of ammeters and voltmeters with increasing accuracy? 1. Moving iron

56.

57.

58.

2. Moving-coil permanent magnet 3. Induction Select the correct answer using the codes given below a. 1, 3, 2 b. 1, 2, 3 c. 3, 1, 2 d. 2, 1, 3 The total current I = I1 + I2 in a circuit is measured as I1 = 150 ± IA, I 2 = 250 ± 2 A , where the limits of error are given as standard deviations. I is measured as a. (400 ± 3)A b. (400 ± 2.24) A c. (400 ± 1/5) A d. (400 ± 1) A Match List I with List II and select the correct answer e: List I (Device/network) A. Twin-T network B. Shielded decade capacitance box C. Wagner earthing arrangement D. Inter bridge transformer List II (Application) 1. For use in accurate a.c. bridge 2. For realizing frequency selective amplifier 3. To match impedance and block d.c. noise in a.c. bridge 4. For minimizing earth capacitance leakage A B C D 2 1 4 3 a. 3 4 1 2 b. 2 4 1 3 c. 3 1 4 2 d. For the bridge shown in the given figure,

at balance the values of Rx , Cx and Qx will be a. Rx = C1R2/C3, Cx = R1C3/R2, Qx = ωC1R1

59.

60.

61.

62.

8 of 16 b. Rx = C1R2/C3, Cx = R1C3/R2, Qx = 1/ωC1R1 c. Rx = C1R1/C3, Cx = R2C3/R1, Qx = 1/ωC1R1 d. Rx = C1R1/C3, Cx = R2C3/R1, Qx= ωC1R1 The reflecting mirror mounted on the moving coil of a vibration galvanometer is replaced by a bigger size mirror. This will result in a. lower frequency of resonance & lower amplitude of vibration b. lower frequency of resonance but the amplitude of vibration is unchanged c. higher frequency of resonance & lower amplitude of vibration d. higher frequency of resonance but the amplitude of vibration is unchanged Consider the following statements associated with moving iron instruments 1. These can be used in d.c. as well. a.c. circuits 2. The scale is non-uniform 3. The moving iron is placed in a field. of a permanent magnet Which of these statements are correct? a. 1, 2 and 3 b. 1 and 2 c. 2 and 3 d. 1 and 3 A screen pattern oscillogram, shown in the given figure is obtained when a sine-wave signal of unknown frequency is connected to the vertical input terminals, and at the same time, a 600 Hz sine-wave voltage is connected to the horizontal input terminals of an oscilloscope

What is the value of unknown frequency? a. 300 Hz b. 400Hz c. 600Hz d. 900Hz Which of the following statements is NOT correct for a storage type oscilloscope?

63.

a. The storage target is a conductive mesh covered with magnesium fluoride. b. Secondary emission electrons etch a positively charged pattern c. The flood guns used for display, emit nigh velocity electrons d. The flood guns are placed between the deflection plates and storage target In an oscilloscope, two Lissajous figure (X) and (Y) are observed. This indicates that ratio of vertical input signal frequency to that of horizontal input frequency are

67.

68.

64.

65.

66.

a. 5/3 for X and 3/2 for V b. 3/2 for X and 5/3 for Y c. 5/3 for X and 5/3 for Y d. 3/2 for X and 3/2 for Y A spring controlled moving iron voltmeter draws a current of 1 mA for full scale value of 1000 V. If it draws a current of 0.5 mA, the meter reading is a. 25 V b. 50 V c. 100 V d. 200 V In the measurement of power on balanced load by two-Wattmeter method in a 3phase, circuit, the readings of the Wattmeter are 3 kW and 1 kW respectively, the latter being obtained after reversing the connections to the current coil. The power factor of the load is a. 0.277 b. 0.554 c. 0.625 d. 0.866 Two types of connections of Wattmeter pressure coil are shown in the figure,

69.

70.

71.

9 of 16 The value of the Wattmeter current coil resistance r, which makes the connection errors the same in the two cases is a. 0.05 Ω b. 0.1 Ω c. 0.01 Ω d. 0.125 Ω In calibration of a dynamometer Wattmeter by potentiometer, phantom loading arrangements is used because a. The arrangement gives accurate results b. The power consumed in calibration work is minimum c. The method gives quick results d. The onsite calibration is possible The accuracy of Kelvin’s double bridge for the measurement of low resistance is high because the bridge a. User two pairs of resistance arms b. Has medium value resistance in the ratio arms c. Uses a low resistance link between standard and test resistances d. Uses a null indicating galvanometer An imperfect capacitor is represented bya capacitance C in parallel with a resistance R. The value of its dissipation facto tan δ is a. ω C R b. ω2 C R c. 1/ω2 C R d. 1/ω C R An energy-meter having a meter constant of 1200 rev per kWH is found to make 5 revolutions in 75s. The load power is a. 500 W b. 100 W c. 200 W d. 1000 W Which one of the following statements is NOT true? a. Potentiometric Linear displacement can give high output signal b. Linear variable differential transformer has low output impedance c. Synchros and resolves have low accuracy d. Eddy current proximity transducers are non-contact type transducers

72.

73.

74.

Match List I with List II and select the correct answer: List I (Transducer) A. Mercury in glass thermometer B. Platinum resistance thermometer C. Thermocouple with led compensation, D. Optical radiation pyrometer List II (Range of temperature) 1. Can be used upto 300°C in normal conditions 2. Can be used upto 900°C with sufficient accuracy 3. Can be used upto 1400°C 4. Can be used for temperatures upto several thousand degrees A B C D a. 3 2 1 4 1 4 3 2 b. 3 4 1 2 c. d. 1 2 3 4 Match list I with List II and select the correct answer List I (Instrument) A. McLeod gage B. Turbine meter C. Pyrometer D. Synchros List II (Measurand) 1. Temperature 2. Pressure. 3. Flow 4. Displacement A B C D 1 4 2 3 a. 2 3 1 4 b. 1 3 2 4 c. d. 2 4 1 3 In a stroboscopic method of rotational speed measurement of a machine shaft, N = the machine shaft speed of rotation of the shaft in revolutions 1mm. n = No. of paints on the circuit pattern F = No of flash per mm. The speed of rotation N will be a. N = F + n b. N = F - n c. N = F/n d. N = F.n

75.

10 of 16 To reduce the effect of noise level, 100 sets of data are averaged. The averaged data set will have a noise level reduced by a factor of a. 10 b. 10 2

76.

c. 50 2 d. 100 Which of the following transducers is classified as an active transducer? a. Metallic strain gauge b. Capacitive microphone c. LVDT d. Piezoelectric transducer

77.

78.

79.

80.

Which curve in the given figure represents resistance temperature characteristics of a thermistor? a. Curve A b. Curve B c. Curve C d. Curve D A 1 cm piezoelectric transducer having a g-coefficient of 58 V/kg/m2 is subjected to a constant pressure of 10’ kg/m2 for about 15 minutes. The Piezo voltage developed by the transducer will be a. 116 mV b. 58 mV c. 29 mV d. 0 mV If K is the number of parity bits provided with a message, the numbers of errors which can be detected are? a. K b. K – 1 c. K + 1 d. dependent upon the number of bits in. the message also Which of the following are the characteristics of closed- loop systems? does not compensate for 1. It disturbances

11 of 16 2. It reduces the sensitivity of plantparameter variations 3. It does not involve output measurements 4. It has the ability to control the system transient response Select the correct answer using the codes given below: a. 1 and 4 b. 2 and 4 c. 1 and 3 d. 2 and 3

3.

4.

81. Codes;

82.

The number of forward paths and the number of non-touching loop pairs for the signal flow graph given in the figure are respectively, a. 1, 3 b. 3, 2 c. 3, 1 d. 2, 4 List I and List II show the transfer function and polar plots respectively. Match List I with list II and select the correct answer: List I 1 A. s (1 + sT ) B. C. D.

83.

1

(1 + sT1 )(1 + sT2 ) 1

s (1 + sT1 )(1 + sT2 ) 1 s (1 + sT1 )(1 + sT2 ) 2

84.

List II 1.

2. 85.

A B C D 2 1 4 3 a. b. 3 4 1 2 2 4 1 3 c. d. 3 1 4 2 Match List I with List II and select the correct answer: List I (Property) A. Relative stability B. Speed of response C. Accuracy D. Sensitivity List II (Specification) 1. Rise time 2. Velocity error constant 3. Return difference 4. M-peak Codes; A B C D 4 3 2 1 a. b. 2 1 4 3 c. 4 1 2 3 2 3 4 1 d. Given the transfer function 121 G (s) = of a system. Which s + 13.2 s + 121 of the following characteristics does it have? a. Over damped and settling time 1.1s b. Under damped and settling time 0.6s c. Critically damped and settling time 0.8s d. Under damped and settling time 0.707s

88.

86.

87.

The steady-state error resulting from an input r(t) = 2 +3t + 4t2 for given state is a. 2.4 b. 4.0 c. Zero d. 3.2 If a ramp input is applied to Type-2 system, the steady- stage error is a. positive constant b. negative constant c. zero d. positive infinity Identify the correct root locus from the figures given below referring to poles and zeros at ± j 8 and ± j 10 respectively of G(s) H(s) of a single-loop control system. a.

b.

12 of 16 Which of the following are the characteristics of the root locus of K ( s + 5) G (s) = ( s + 1)( s + 3) 1. It has one asymptote 2. It has intersection with j w-axis 3. It has two real axis intersections 4. It has two zeros at infinity Select the correct answer using the codes given below a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 1 and 3

89.

The closed loop system shown above becomes marginally stable if the constant K is chosen to be a. 10 b. 20 c. 30 d. 40 90.

c.

d.

Consider the Nyquist diagram for given KG(s) H(s). The transfer function KG(s)H(s) has ho poles and zeros in the right half of s-plane. If the (-1, j0) point is located first in region I and then in region II, the change in stability of the system will be from a. unstable to stable b. stable to stable c. unstable to unstable d. stable to unstable

91.

92.

93.

94.

The characteristic equation of a system is given by 3s 4 + 10 s 3 + 5s 2 + 2 = 0 . This system is a. Stable b. Marginally stable c. Unstable d. Neither (a), (b) not (c) Match List I with List II and select the correct answer: List I A. Phase lag controller B. Addition of zero at origin C. Derivative output compensation D. Derivative error List II 1. Improvement in transient response 2. Reduction in steady-state error 3. Reduction in settling time 4. Increase in damping constant Codes; A B C D a. 4 3 1 2 b. 2 4 3 4 4 1 3 2 c. d. 2 3 1 4 Indicate which one of the following transfer functions represents phase lead compensator? s +1 a. s+2 6s + 3 b. 6s + 2 s+5 c. 3s + 2 s +8 d. s + 5s + 6 A transfer function of a control system does not have pole-zero cancellation. Which one of the following statements is true? a. System is neither controllable nor observable b. System is completely controllable and observable c. System is observable but uncontrollable d. System is controllable but unobservable

95.

13 of 16 A linear time invariant system is described by the following dynamic equation dx ( t ) / dt = Ax ( t ) + Bu ( t ) y ( t ) = Cx ( t )

96.

97.

⎡0 ⎤ ⎡0 1⎤ , B = ⎢ ⎥ , C = [1 1] Where A = ⎢ ⎥ ⎣ −2 −3⎦ ⎣1 ⎦ The system is a. Both controllable and observable b. Controllable but unobservable c. Observable but uncontrollable d. Both uncontrollable and unobservable The state-space representation in phasevariable from for the transfer function 2s + 1 G (s) = 2 s + 7s + 9 ⎡0 1⎤ ⎡0 ⎤ a. x = ⎢ x + ⎢ ⎥ u; y = [1 2] x ⎥ ⎣ −9 −7 ⎦ ⎣1 ⎦ 0⎤ ⎡1 ⎡0 ⎤ b. x = ⎢ x + ⎢ ⎥ u; y = [ 0 1] x ⎥ ⎣ −9 −7 ⎦ ⎣1 ⎦ ⎡ −9 0 ⎤ ⎡0⎤ x + ⎢ ⎥ u; y = [ 2 0 ] x c. x = ⎢ ⎥ ⎣ 1 −7 ⎦ ⎣1 ⎦ ⎡ −9 0 ⎤ ⎡0⎤ d. x = ⎢ x + ⎢ ⎥ u; y = [1 2] x ⎥ ⎣ 1 0⎦ ⎣1 ⎦ ⎡1 2 ⎤ ⎡0 ⎤ X + ⎢ ⎥U Let X = ⎢ ⎥ ⎣0 1 ⎦ ⎣1 ⎦ Y = [b

0] X

Where b is an unknown constant This system is a. Observable for all values of b b. Unobservable for all values of b c. Observable for all non-zero values of b d. Unobservable for all non-zero values of b 98.

Select the correct transfer function v0 ( s ) / v1 ( s ) from the following for the given network. 2 a. s ( s + 1)

The describing function nonlinearity will be 4MK a. πx 4M b. K + πx

s b. ( s + 2)

99.

100.

101.

c.

s ( 2s + 1)

d.

2s ( s + 1)

Which one of the following statements is INCORRECT with reference to pneumatic system? a. Operating pressure is low compared to hydraulic system b. Leaks can create problems as well as fire hazards c. They are insensitive to temperature changes d. High compressibility of air results. in longer time delays Consider the following statements regarding A.C. servo- motor 1. The torque-speed curve has negative slope 2. It is sensitive to noise 3. The rotor has high resistance and low inertia 4. It has slow acceleration Which of the following are the characteristics of A.C. servo-motor as control component? a. 1 and 2 b. 2 and 3 c. 1 and 3 d. 2 and 4 Backlash in a stable control system may cause a. under damping b. over damping c. high level oscillations d. low level oscillations

of

14 of 16 given

4M 1 − K 2 πx 4M d. π Kx Consider the following statements 1. If the input is a sine wave of radian frequency o, the output in general is non-sinusoidal containing frequencies which are multiple of w 2. The jump resonance may occur 3. The system exhibits self-sustained oscillation of fixed frequency and amplitude 4. The response to a particular test signal is a guide to the behaviour to other inputs Which of the above statements are correct and peculiar to nonlinear system? a. 1, 3 and 4 b. 2, 3 and 4 c. 1, 2 and 3 d. 1, 2 and 4 For the given sampled-data system

c.

103.

104.

The z-transform is a.

b.

c.

102.

d.

The describing function of relay nonlinearity is 4M/X : M = Magnitude of relay, X = Magnitude of input.

105.

The output of first order hold between two consecutive sampling instants is a a. Constant b. Quadratic function

106.

107.

108.

109.

c. Ramp function d. Exponential function match List I with List II and select the correct answer: List I (Elements) A. Controller B. Sampler C. Hold List II 1. A/D convereter 2. Computer 3. D/A converter A B C 3 1 2 a. 2 3 1 b. 3 2 1 c. 2 1 3 d. Assertion (A):

∫ B.ds = 0

110.

where B =

magnetic flux density ds = vector with direction normal to surface element ds. Reason (R): Tubes of magnetic flux have no sources or sinks. a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Consider a plane electromagnetic wave incident normally on the surface of a good conductor. The wave has an electric field of amplitude 1 (V/m) and the skin depth for the conductor is 10 cm. Assertion (A): The amplitude of electric field is (1/e2) (V/m) after the wave has travelled a distance of 20 cm in the conductor. Reason (R): Skin depth is the distance in which the wave amplitude decays to (1/e) of its value at the surface a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): When an alternating field is applied to a dielectric, the relative permittivity is a complex quantity.

111.

112.

15 of 16 Reason (R): The imaginary part of the relative permittivity is responsible for dielectric loss. a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): A doped semiconductor will behave as a perfect insulator at zero Kelvin but its electrical conductivity will rise if the temperature is slowly increased above zero Kelvin. Reason (R): The rise in electrical conductivity is mainly, due to increased ionization as the temperature is raised above zero Kelvin. a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Node-voltage analysis of networks is a method that used Kirchoff’s current law to obtain a set of simultaneous equations that, when solved, will provide information concerning the magnitudes and phase angles of the voltages across each branch. Reason (R): The ideal generator maintains a constant voltage amplitude and waveshape regardless of the amount of current it supplied to the circuit. a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): All networks made up of passive, linear time invariant elements are reciprocal. Reason (R): Passivity and time-invariance of elements do not guarantee reciprocity of the network. a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A

113.

114.

115.

116.

c. A is true but R is false d. A is false but R is true Assertion (A): Transfer impedance of network is always the reciprocal of its transfer admittance. Reason (R): The impedance of a network is the reciprocal of its admittance. a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): There are pulsations in power of a balanced three-phase system. Reason (R): The three-phase generators produce sinusoidal voltages and current. a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): A full-wave rectifier type a.c. voltmeter reads the true rms value of the input wave4orm. Reason (R): The full wave rectifier type a.c. voltmeter has a rectifier unit first which feeds its output to the PMMC indicative instrument. a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): A four-arm ‘Wien’ bridge network is sometimes used in feedback circuit of tuned amplifier. Reason (R): The balance equation of such a Wien bridge contains ‘frequency’ term along with arm parameters. a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true

117.

118.

119.

120.

16 of 16 Assertion (A): A spectrum analyzer displays the frequency spectrum of a signal on the CRT screen. Reason (R): It uses a sweep voltage generator to sweep the electron beam as well as the input signal. a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): A system may have no steady state error to a step input, but the same system may exhibit non zero steady state error to ramp input. Reason (R): The steady state error of a system depends on the ‘type’ of the open loop transfer function. a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Relative stability o a system reduces due to the presence of transportation lag. Reason (R): Transportation lag can be conveniently handled by Bode plot. a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): If any one of the state variables is independent of the control u(t), the process is said to be completely uncontrollable. Reason (R): There is no way of driving this particular state variable to a desired state in finite time by means of a control effort. a. Both A & B are true and R is the correct explanation of A b. Both A & R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true

1 of 15

I.E.S-(OBJ) 2003

ELECTRICAL ENGINEERING PAPER-I 1.

2.

3.

Consider the following statements with reference to a system with velocity error constant Ky = 1000 1. The system is stable. 2. The system is of type 1 3. The test signal used is a step input. Which of these statements are correct? a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2 and 3 Which one of the following statements is NOT of correct? a. With the introduction of integral control, the steady state error increases b. The generalised error coefficients provide a simple way of determining the nature of the response of a feedback control to any arbitrary input c. The generalized error coefficients lead to calculation of complete steady state response without actually solving the system differential equation d. For a type-1 system, the steady state error for acceleration input is infinite Consider the following statements with reference to the root loci of the characteristic equation of unity feedback control system with an open loop transfer function of K ( s + 1)( s + 3)( s + 5) G(s) = s ( s + 2) 1. Each locus starts at an open loop pole and ends either at an open loop zero or infinity 2. Each locus starts at an open loop pole or infinity and ends at an open loop zero. 3. There are three separate root loci. 4. There are five separate root loci. Which of these statements are correct ? a. 2 and 3 b. 2 and 4 c. 1 and 3

d. 1 and 4 4.

5.

The Bodge phase angle plot of a system is shown above. The type of the system is a. 0 b. 1 c. 2 d. 3 The loop transfer function of a system is given by: K ( s + 10) 2 ( s + 100) G(s) = s ( s + 25) The number of loci terminating at infinity is a. 0 b. 1 c. 2 d. 3

6.

The Nyquist plot of a unity feedback K ( s + 3)( s + 5) system having open G ( s ) = ( s − 2)( s − 4) loop transfer function for K = 1 is as shown above. For the system to be stable, the range of values of K is a. 0 < K < 1.33 b. 0 < K < 1/1.33 c. K > 1.33 d. K > 1/1.33 7.

The Nyquist plot of a control system is shown above. For this system, G(s) H(s) is equal to K a. s(1 + sT1 )

b.

K s (1 + sT1 )

c.

K s (1 + sT1 )

d.

K s (1 + sT1 ) s (1 + sT1 )

11.

2

3

2

8.

12.

9.

10.

The pole-zero map and the Nyquist plot of the loop transfer function GH(s) of a feedback system are shown above. For this a. Both open loop and closed loop system are stable b. Open loop system is stable but closed loop system is unstable c. Open loop system is unstable but closed loop system is stable d. Both open loop and closed loop systems are unstable A property of phase-lead compensation is that the a. Overshoot is increased b. Bandwidth of closed lop system is reduced c. Rise-time of closed loop system is reduced d. Gain margin is reduced Which one of the following statements is NOT correct ? a. The transfer function of a lag-lead compensation network is (1 + sT1a )(1 + sT2b) (a > 1, b < 1) (1 + sT1 )(1 + sT2 ) b. Bridged T-network is used for cancellation compensation

2 of 15 c. Phase-lag compensation improves steady state response and often results in reduced rise time d. Compensating network can be introduced in the feedback path of a control system Consider the following statements with respect to a system represented by its statespace model X = AX + Bu and Y = CX 1. The static vector X of the system is unique. 2. The Eigen values of A are the poles of the system transfer function 3. The minimum number of state variables required is equal to the number of independent energy storage elements in the system. Which of these statements are correct ? a. 1 and 2 b. 2 and 3 c. 1 and 3 d. 1, 2 and 3 The state-space representation of a system is given by ⎡ −1 0 ⎤ ⎡1 ⎤ ⎡1⎤ X =⎢ X + ⎢ ⎥ U and Y = ⎢ ⎥ X ⎥ ⎣ 0 −2 ⎦ ⎣0⎦ ⎣1⎦

Then the transfer function of the system is 1 a. 2 s + 3s + 2 1 b. s+2 1 c. 2 s + 3s + 2 1 d. s +1

13.

A seismic transducer using a spring-massdamper system as shown above will have an output displacement of zero when the input xi is a a. Constant displacement b. Constant velocity c. Constant acceleration

3 of 15 14.

15.

16.

d. Sinusoidal displacement Match List I with List II and select the correct answer: List I (Component) A. Input potentiometer in d.c. system B. Synchro pair in a.c. system C. Motor D. Feedback tachogenerator List II (Purpose) 1. Actuator 2. Error detector 3. Transducer A B C D 3 2 3 1 a. 2 3 1 3 b. 2 3 3 1 c. 3 2 1 3 d. Which one of the following statements is NOT correct? a. The action of bellows in pneumatic control system is similar to that of a spring b. The flapper value converts large changes in the position of the flapper into small changes in the back pressure c. The common name of pneumatic amplifier is pneumatic relay d. The transfer function of a pneumatic actuator is of the form : A 2 Ms + fs + K Match List I (Root Locations) with List II (Phase Plane Plots) and select the correct answer : List I A.

B.

C.

D.

List II 1.

2.

3.

4.

17.

A B C D 3 2 1 4 a. 2 3 4 1 b. 3 2 4 1 c. 2 3 1 4 d. Match List I (Nonlinearity) with List II (Characteristics) and select the correct answer: List I A. Saturation B. ldealstiction and Coulomb friction C. Dead Zone D. Relay with hysteresis List II 1.

4 of 15 using bilinear 1+ ω transformation Z = 1− ω 3. A discrete data system is unstable if any of roots of the characteristic equation lies within the unit circle on the complex plane. Which of these statements is/are correct? a. 1 and 2 b. 1 and 3 c. 3 only d. 2 and 3 Assertion (A) : The test charge may have any value while defining electric field intensity. Reason (R) : The test charge should not disturb the field being measured. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The scalar magnetic potential is evidently the quantity whose equipotential surfaces will form curvilinear squares with the stream lines of H. Reason (R) : The scalar magnetic potential satisfies Laplace’s equation where J = 0. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : For steady current in an arbitrary conductor, the current density is solenoidal. Reason (R) : The reciprocal of the resistance is the conductivity. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Displacement current can have only a.c. components. Reason (R) It is generated by a change in electric flux. data

2.

3. 21.

4.

18.

19.

20.

A B C D 3 1 2 4 a. 1 3 2 4 b. 3 1 4 2 c. 1 3 4 2 d. Which one of the following methods is NOT used for the analysis of nonlinear control systems? a. Phase plane method b. Describing function method c. Liapunov’s method d. Piecewise linear method The transfer function of ZOH (Zero Order Hold) is a. 1–eTs b. 1–e–Ts 1 − eTs c. s 1 − e − Ts d. s Consider the following statements: 1. A discrete-time system is said to be stable if and only if its response of unit impulse δ(t) decays with k. 2. Routh-Herwitz testing may be applied to determine the stability of discrete-

22.

23.

24.

system

25.

26.

27.

28.

a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : A uniform plane wave is a transverse electromagnetic wave. Reason (R) : A uniform plane wave can physically exist and represent finite energy. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Energy released when an electron jumps from a higher to a lower level is usually in the form of photons. Reason (R) : Energy released when an electron jumps from a higher to a lower level is absorbed by the nucleus. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Lepidolite type mica is un suitable for electric insulation. Reason (R) : Lepidolite is hard and brittle. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Glazing is done on ceramic insulators to make the surface smooth and non-absorbent. Reason (R) : Moisture from the atmosphere can collect on the surface discontinuities on a ceramic and result in electrical breakdown. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true

29.

30.

31.

32.

33.

5 of 15 Assertion (A) : In a series R-L-C circuit, the current is a minimum at resonant frequency. Reason (R) : The maximum voltage across the capacitor occurs at a frequency lower than the resonant frequency. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : A Schering Bridge used for testing of a porcelain insulator is shielded by a metallic screen. Reason (R) : Earth’s magnetic field is blocked by a metallic screen. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Multiplexing of signals is in variably used in telemetry systems.. Reason (R) : Multiplexing improves signal to noise ratio over the communication channel and at destination. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) Magnetic tape is not used for digital data recording directly. Reason (R) : Digital data require high speed recording. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) Stability of a system deteriorates when integral control is incorporated in it. Reason (R) : With integral control order of the system increases, and higher the order of the system the more the system tends to become unstable.

34.

35.

36.

a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Use of lead compensation results in increased system bandwidth. Reason (R) : The angular contribution of the compensator pole is more than that of the compensator zero. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Tachogenerator feedback is used as minor loop feedback in position control systems to improve stability. Reason (R) : Tachogenerator provides velocity feedback which decreases the damping in the system a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Servomotor normally have heavier rotors and lower RIX ratio as compared to ordinary motors of similar ratings. Reason (R) : Servomotors should have smaller electrical and mechanical time constants for faster response. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true

6 of 15 current I is 3 and 1.5 respectively. The value of 1 for R = 1 will be a. 0.5 b. 1.5 c. 2.0 d. 3.0 38.

For the circuit shown above, the value of VS is 0 when I = 4 A. The value of I when V = 16 V, is a. 6 A b. 8 A c. 10 A d. 12 A 39.

The linear network as shown above has only resistors. If I1 8 A and I2 = 12 A; V is found to be 80 V. V = 0 when I1 = –8 A and I2 = 4 A. Then the value of V when I1 = I2 = 10 A, is a. 25 V b. 50 V c. 75 V d. 100 V 40.

37.

41. The black box as. shown in the circuit above contains resistors and independent sources. For R = 0 and 2, the value of

The total impedance of Z (jω) of the circuit shown above is a. (6 + i0) Ω b. (7 + j0) Ω c. (0 + j8) Ω d. (6 + j8) Ω The impedance of a parallel RLC network 5s is Z ( s ) = 2 . Then the value s + 0.5s + 100 of R, L and C are, respectively

7 of 15

42.

a. 10 Ω, 1/20 H, 1/5 F b. 1 Ω, 1/2 H, 1/5 F c. 10 Ω, 1/20 H, 1/2 F d. 2 Ω, 1/20 H, 1/5 F For a driving point impedance function s +α Z (s) = the voltage will lead the s+β current sinusoidal input, iff a. α and β real positive and α > β b. α is real positive and β is real negative and α > β c. α and β are real positive and β > α d. α and β are real negative and β > α

43.

a. YA + YB ⎛ Y Y ⎞ b. YC + ⎜ A B ⎟ ⎝ YA +YB ⎠

46.

47.

The lattice circuit has the following impedances ZA = 3 + j4, ZB = 3 – j4. Then the Z-parameters would be 0 ⎞ ⎛ 3 + j4 a. ⎜ ⎟ 3 − j4 ⎠ ⎝ 0

The impedance Z(s) in the above circuit is ⎞ 1⎛ s + ( R / L) a. ⎜ 2 ⎟ C ⎝ s + ( R / L) s + (1/ LC ) ⎠ b.

⎞ 1⎛ s + (1/ RC ) ⎜ 2 ⎟ L ⎝ s + (1/ RC ) s + (1/ LC ) ⎠

c.

⎞ 1⎛ s + ( R / L) ⎜ 2 ⎟ L ⎝ s + (1/ RC ) s + (1/ LC ) ⎠

⎞ 1⎛ s + (1/ RC ) ⎜ 2 ⎟ C ⎝ s + ( R / L) s + (1/ LC ) ⎠ A unit step current of 1 A is applied to a network whose driving point impedance is V (s) s+3 Z (s) = = . 1( s ) ( s + 2) 2 Then the steady state and initial values of the voltage developed across the source are respectively a. (3/4 V, 1 V) b. (1/4 V, 3/4 V) c. (3/4 V, 0 V) d. (1 V, 3/4 V)

⎛ 3 − j4 ⎞ b. ⎜ ⎟ ⎝ − j4 3 ⎠ 3 ⎞ ⎛ 3 + j4 c. ⎜ ⎟ 3 + j4 ⎠ ⎝ 3 3 ⎞ ⎛ − j4 d. ⎜ ⎟ ⎝ 3 + j4 ⎠

d. 44.

48.

45.

49.

For the two-port network as shown above, Y12 is equal to

c. –YC d. YC The driving point impedance function s 2 + 2s + 2 Z (s) = 2 can be realized as a s + s +1 a. R-C network b. R-L network c. L-C network d. R-L-C network

In the circuit shown above, the initial voltage across capacitor is 2 V and I is a unit step current source. Then the voltage across the capacitor for t > 0 is a. (2–e–2t) u(t) b. (2 + e2t) u(t) c. (1–e2t) u(t) d. (1 + e–2t) u(t) A circuit is modelled by the following differential equation : d 2i (t ) 6di (t ) + + 9i (t ) = 0 dt 2 dt

The response i(t) is of the form (with symbols having their standard meanings) a. K1e–1 + K2e–9t b. Ke–3t sin (t + θ) c. (K1 + K2t) e–3t d. Ke–t . sin (9t + θ) 50.

52.

53. The capacitor in the circuit as shown above is initially charged to 12 V with S1 and S2 open S1 is closed at t = 0 while S2 is closed at t = 3. The waveform of the capacitor is represented by a.

8 of 15 Hz. The average power dissipated by the inductor is a. 0 W b. 0.25 W c. 0.5 W d. 1.0 W An electromagnetic field is said to be conservative when a. ∇2E = μ ∈ (∂2E / ∂t2) b. ∇2 H = μ ∈ (∂2H / ∂t2) c. Curl of the field is zero d. Divergence of the field is zero A charge is uniformly distributed throughout the sphere of radius a. Taking the potential at infinity as zero, the potential at r = b < a is b Qr a. − ∫ dr 4πε 0 a 3 ∝ b

b. − ∫ ∝ a

c. − ∫ ∝ a

d. − ∫

Q 4πε 0 r 2

b

Q 4πε 0 r

dr

2

Qr dr 4πε 0 r 3 ∝

dr − ∫

Q

dr 4πε 0 r 2 Consider the following statements relating to Laplace’s equation: 1. Solution of Laplace’s equation with two different approved methods lead to different answers. 2. Every physical problem satisfying Laplace’s equation must contain at least two conducting boundaries. 3. Every field (if ρv = 0) satisfies Laplace’s equation. 4. Every conceivable configuration of electrodes or conductors produces a field for which ∇2v = 0. Which of these statements are correct ? a. 1, 3 and 4 b. 3 and 4 c. 1 and 2 d. 2, 3 and 4 Which one of the following pairs is NOT correctly matched? a. Gauss Theorem : ∫ D.d s = ∫ ∇.Ddv ∝

54. b.

c.

d. 55.

51.

A 10 mH inductor carries a sinusoidal current of 1 A r.m.s. at a frequency of 50

s

b. Gauss’s Law :

v

∫ D.d s = ∫ ρdv v

9 of 15

dφ c. Coulomb’s Law : V = − m dt d. Stoke’s Theorem :

60.

^

H = 0.5exp [ −0.1x ] sin(106 t − 2 x) a z ( A / m)

which one of the following statements is NOT correct?

∫ ξ .d l = ∫ ( ∇ × ξ ).d s 1

56.

s

^

a. Wave is linearly polarized along az

Which ones of the following formulae is NOT correct for the boundary between two magnetic materials? a. Bn1 = Bn2 b. B2 = Bn 2 + Bt 2 c. H1 = Hn1 + H11 ^

(

)

b. The velocity of the wave is 5 × 105 m/s c. The complex propagation constant is (0.1 — j2) ^

d. The wave is travelling along ax 61.

^

d. a n21 × H1 − H 2 = K , where a n21 is a

57.

58.

59.

Given that :

unit vector normal to the interface and directed from region 2 to region 1 Interface of two regions of two magnetic materials is current-free. The region 1, for which relative permeability μr1 = 2 is defined by z > 0, and region 2, z > 0 has μr2 = 1. If B1 = 1.2 ax + 0.8 ay + 0.4 az T ; then H1 is r r r a. 1/μ 0 ⎡⎣ 0.6 a x + 0.4 a y + 0.4 a z ⎤⎦ A/m r r r b. 1/μ 0 ⎡⎣1.2 a x + 0.8 a y + 0.8 a z ⎤⎦ A/m r r r c. 1/μ 0 ⎡⎣1.2 a x + 0.4 a y + 0.4 a z ⎤⎦ A/m r r r d. 1/μ 0 ⎡⎣ 0.6 a x + 0.4 a y + 0.8 a z ⎤⎦ A/m A plane slab of dielectric having dielectric constant 5, placed normal to a uniform field with a flux density of 2 C/m2, is uniformly polarized. The polarization of the slab is a. 0.4 C/m2 b. 1.6 C/m2 V c. 2.0 C/m2 d. 6.4 C/m2

(

Maxwell equation ∇ × E = − ∂ B / ∂t

)

62.

^

is given by E = 10sin(10ωt − π z ) a x + ^

63.

R + jω L , (R, L, G and C are line G + jωC constants) Z OC Z SC , (ZOC and ZSC are the open 2.

and short circuit impedances of the line) 3. V’/l’ , (V’ and I’ are the voltage and current of the wave travelling in the

is

^

∂

∫ E × dl = − ∂t ∫ B.dl

d.

∂ ∫ E × dl = − ∂t

s

∫ B.dl s

10 cos(ωt − π z ) a y (V/m) The polarization of the wave is a. Circular b. Elliptical c. Linear d. Undefined Consider the following statements: Characteristic impedance of a transmission line is given by 1.

represented in integral form as ∂ a. ∫ E.dl = − ∫ B.dl ∂t ∂ b. ∫ E.dl = − ∫ B.d s ∂t s c.

For a conducting medium with conductivity σ, permeability μ and permittivity ε, the skin depth for an electromagnetic signal at an angular frequency ω is proportional to a. σ b. 1/ω c. 1/ σ d. 1/μ The electric field of a uniform plane wave

64.

positive y direction) Which of these are correct? a. 1, 2 and 3 b. 1 and 2 c. 2 and 3 d. 1 and 3 A loss-less transmission line of characteristic impedance Z0 and l < λ/4 is

65.

terminate at the load end by a short circuit. Its input impedance ZS is a. ZS = –j Z0 tan βl b. ZS = j Z0 cot βl c. ZS = j Z0 tan βl d. ZS = –j Z0 cot βl A loss-less transmission line of characteristic impedance 600 ohms is terminated in a purely resistive load of 900 ohms. The reflection coefficient is a. 0.2 b. 0.5 c. 0.667 d. 1.5

66.

72.

Given a vector field A = 2 r cos φ Tr in coordinate. For the contour as shown above, ∫ A.dl is

67.

68.

69.

70.

71.

a. 1 b. 1– (π/2) c. 1+ (π/2) d. –1 The forbidden energy gap in silicon at 300 K is a. 1.41 eV b. 1.1 eV c. 0.785 eV d. 0.72 eV With an increase in temperature., the Fermi level in an intrinsic semiconductor a. Moves closer to the conduction band edge b. Moves closer to the valence band edge c. Moves into the conduction band d. Remains at the centre of the forbidden gap Which one of the following is NOT true for Sulphur Hexafluoride gas? a. It is electronegative in nature b. It has high dielectric strength c. It is non-toxic d. It is highly inflammable Which one of the following materials has the highest dielectric strength?

73.

74.

75.

76.

10 of 15 a. Polystyrene b. Marble c. Cotton d. Transformer oil The losses in a dielectric subject to an alternating electric field are determined by a. Real part ‘of the complex dielectric constant b. Imaginary part of the complex dielectric constant c. Absolute value of the complex dielectric constant d. Ratio of the magnitudes of the real and imaginary parts of the complex dielectric constant In a solid or liquid dielectric with externally applied electric field, as the interatomic distance increases the internal field Ei, a. Increases b. Decreases c. Remains unaltered d. Increases or decreases based on temperature According to Wiedemann-Franz law the ratio of thermal conductivity to electrical conductivity of a conductor of a. Independent of temperature b. Directly proportional to temperature c. Inversely proportional to temperature d. Inversely proportional to square of temperature Which one of the following statements is correct for four-point probe method of determining resistivity? a. The sample must be extrinsic b. The current source is connected to the two inner probes c. One probe point must inject minority carriers d. Current flow only in a small area of the sample The average drift velocity Vd of electrons in a metal is related to electric field E and collision time T as a. Vd = QeET/me b. Vd = meQeT c. Vd = meQeT/2E d. Vd = QeEt/2 me Susceptibility of a diamagnetic material is 1. Negative 2. Positive

77.

78.

79.

3. Dependent on the temperature 4. Independent of the temperature Select the correct answer using the codes given below: a. 1 and 3 b. 2 and 4 c. 1 and 4 d. 2 and 3 Match List I (Magnetic Materials) with List II (Applications) and select the correct answer: List I A. Silicon Steel B. Ferrite C. Alnico List II 1. Current transformer 2. Power transformer 3. Permanent magnet 4. High frequency transformer A B C 1 2 3 a. b. 1 4 2 2 1 4 c. 2 4 3 d. The development of barrier potential in the depletion zone of a PN junction is consequent to a. Diffusion of majority carriers across junction b. Drift of minority carriers across junction c. Generation of minority carriers due to thermal energy d. Initial flow of conduction current The current flow in a certain PN junction at room temperature 300 K is 2 × 10–7 A when a large reverse bias voltage is applied. The current flowing when a forward bias of 0.1 V is applied will be ⎡ −1.6 × 10−19 × 0.1 ⎤ a. 2 × 10–7 exp ⎢ ⎥ −23 ⎣1.38 ×10 × 300 ⎦ ⎡ −1.6 × 10 × 0.1 ⎤ b. 2 × 10–7 × ⎢ ⎥ −23 ⎣1.38 ×10 × 300 ⎦ −19

⎡ −1.38 × 10−23 × 300 ⎤ c. 2 × 10–7 exp ⎢ ⎥ −19 ⎣ 1.6 × 10 × 0.1 ⎦ ⎡1.38 ×10−23 × 300 ⎤ d. 2 × 10–7 × ⎢ ⎥ −19 ⎣ 1.6 × 10 × 0.1 ⎦

80.

81.

82.

83.

11 of 15 On which of the following factors does the electrical conductivity of a semiconductor depend? 1. Carrier concentration 2. Carrier mobility 3. Sign of the carrier Select the correct answer using the codes given below a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2 and 3 An intrinsic semiconductor at a temperature of absolute zero behaves like an insulator because of a. Non-availability of free electrons b. Non-recombination of electrons with holes c. Low drift velocity of free electrons d. Low (almost zero) electron energy Consider the following statements: E nF and E pF are the energies of the Fermi levels on the n and p sides of p-n junction diode, respectively. They will vary with applied bias as follows : 1. E nF and E pF with no bias applied. 2. E nF increased and E pF decreases with forward bias. 3. E nF decreases and E pF increases with reverse bias. 4. E nF decreases and E pF increases with reverse bias. 5. E nF increases and E pF decreases with reverse bias. Select the correct answer using the codes given below : a. 1, 4 and 5 b. 2 and 3 c. 4 and 5 d. 1, 2 and 3 Match List I (Thyristors) with List II (Symbols) and select the correct answer : List I A. Silicon-controlled rectifier (SCR) B. Silicon-controlled switch (SCS) C. Silicon-unilateral switch (SUS) D. Light-activated SCR (LASCR) List II 1.

12 of 15

2.

Consider the circuit as shown above which has a current-dependent current source. The value V2/V1 is a. 1 b. 2 1+ α c. 2 +α

3.

4. 87.

84.

A B C D 3 4 1 2 a. 4 3 1 2 b. 3 4 2 1 c. 4 3 2 1 d. In a network made up of linear resistors and ideal voltage sources, values of all resistors-are doubled. Then the voltage across each resistor is a. Doubled b. Halved c. Decreases four times d. Not changed

85.

88.

The incandescent bulbs rated respectively as P1 and P2 operation at a specified mains voltage are connected in for series across the mains as shown in the above figure. Then the total power supplied by the mains to the two bulbs is P1 P2 a. P1 + P2 b.

86.

α

d.

89.

P12 + P22

c.

( P1 + P2 )

d.

P1 × P2 90.

2 +α A certain network consists of a large number of ideal linear resistances, one of which is designated as R and two constant ideal sources. The power consumed by R is P1 when only the first source is active and P2 when only the second source is active. If both sources are active simultaneously, then the power consumed by R is a. P1 ± P2 P1 ± P2 b. c.

(

d.

( P1 ± P2 )

P1 ± P2

)

2

2

Torque / Weight ratio of an instrument indicates a. Selectivity b. Accuracy c. Fidelity d. Sensitivity Which of the following are data representation elements in a generalized measurement system ? 1. Analog indicator 2. Amplifier 3. A/D converter 4. Digital display Select the correct answer using the codes given below: a. 1 and 2 b. 1 and 4 c. 2 and 4 d. 3 and 4 A first order instrument is characterized by a. Time constant only b. Static sensitivity and time constant

91.

92.

93.

94.

95.

96.

c. Static sensitivity and damping coefficient d. Static sensitivity, damping coefficient and natural frequency of oscillations Wire-wound resistors are unsuitable for use at high frequencies because a. They are likely to melt under excessive eddy current b. They exhibit unwanted inductive and capacitive effects c. They create more electrical noise d. They consume more power Decibel scale is useful while measuring voltages covering a. Wide frequency ratio b. Wide voltage ratio c. Narrow frequency range d. Narrow voltage range A standard resistance is made ‘Bifilar’ type of eliminate a. Stray capacitance b. Temperature effect c. Inductive effect d. Skin effect Standard cell a. Will have precise and accurate constant voltage when current drawn from it is few microamperes only b. Will have precise and accurate constant voltage when few milliamperes are drawn from it c. Will continue to have constant voltage irrespective of loading conditions d. Can supply voltages up to 10 V For time and frequency, the working standard is a. Microwave oscillator b. Crystal controlled oscillator c. Laser d. Arf oscillator A C.R.C. is operated with X and Y settings of 0.5 ms/cm and 100 mV/cm. The screen of the C.R.O. is 10 cm × 8 cm (X and Y). A sine wave of frequency 200 Hz and r.m.s. amplitude of 300 mV is applied to the Y-input. The screen will show a. One cycle of the undistorted sine wave b. Two cycles of the undistorted sine wave c. One cycle of the sine wave with clipped amplitude

97.

98.

99.

100.

101.

102.

13 of 15 d. Two cycles of the sine wave with clipped amplitude The difference between the indicated value and the true value of a quantity is a. Gross error b. Absolute error c. Dynamic error d. Relative error Vibration galvanometers, tuneable amplifiers and head phones are used in a. d.c. bridges b. a.c. bridges c. Both d.c. and a.c. bridges d. Kelvin double bridge A Wien-bridge is used to measure the frequency of the input signal. However, the input signal has 10% third harmonic distortion. Specifically the signal is 2 sin 400 πt + 0.2 sin 1200 πt (with t in sec.). With this input the balance will a. Lead to a null indication and setting will correspond to a frequency of 200 Hz b. Lead to a null indication and setting will correspond to 260 Hz c. Lead to a null indication and setting will correspond to 400Hz d. Not lead to null indication Which one of the following multi-range voltmeters has high and constant input impedance ? a. Permanent magnet moving coil voltmeter b. Electronic voltmeter c. Moving iron voltmeter d. Dynamometer type voltmeter In a Q-meter measurement to determine the self capacitance of a coil, the first resonance occurred at f1 with C1 = 300 pF. The second resonance occurred at f2 = 2f1 with C2 = 60 pF. The self-capacitance of coil works out to be a. 240 pF b. 60 pF c. 360 pF d. 20 pF A multimeter is used for the measurement of the following: 1. Both a.c. and d.c. voltage 2. Both a.c. & d.c. voltage 3. Resistance 4. Frequency

103.

104.

105.

106.

107.

108.

5. Power Select the correct answer using the codes given below: a. 1, 2 and 4 b. 1, 2 and 5 c. 1, 3 and 5 d. 1, 2 and 3 Which one of the following truly represents the output on the screen of spectrum analyzer when an amplitude modulated wave is connected to it? a. Single vertical line on the screen b. Two vertical lines on the screen c. Three vertical lines with amplitude d. Three vertical lines out of which two have equal magnitude Three d.c. voltmeters are connected in series across a 120 V d.c. supply. The voltmeters are specified as follows: Voltmeter A : 100 V, 5 mA Voltmeter B : 100 V, 250 ohms/V Voltmeter C : 10 mA, 15,000 ohms The voltages read by the meters A, B and C are, respectively a. 40, 50 and 30 V b. 40, 40 and 40 V c. 60, 30 and 30 V d. 30, 60 and 30 V The capacitance and loss angle of a given capacitor specimen are best measured by a. Wheatstone bridge b. Maxwell bridge c. Anderson bridge d. Schering bridge The energy capacity of a storage battery is rated in a. kwh b. kw c. Ampere hours d. Joules The pressure coil of an induction type energy meter is a. Highly resistive b. Highly inductive c. Purely resistive d. Purely inductive Match List I (Parameter) with List II (Transducer) and select the correct answer: List I A. Pressure B. Temperature

109.

110.

111.

112.

113.

114.

14 of 15 C. Displacement D. Stress List II 1. Thermistor 2. Piezoelectric crystal 3. Capacitance transducer 4. Resistance strain gauge 5. Ultrasonic waves A B C D 1 2 5 3 a. 2 1 4 3 b. c. 1 2 5 4 2 1 3 4 d. Measurement of flow, thermal conductivity and liquid level using thermistors make use of a. Resistance decrease with temperature b. Resistance increase with temperature c. Self-heating phenomenon d. Change of resistivity Pair of active transducers is a. Thermistor : Solar cell b. Thermocouple; Thermistor c. Thermocouple; Solar cell d. Solar cell; LVDT Sensitivity of LVDT is mainly due to a. Magnetic shielding of the core b. Permeability of the core c. Exact cancellation of secondary voltages d. Insulation used in the winding A strain gauge with a resistance of 250 ohms undergoes a change of 0.150 ohm during a test. The strain is 1.5 × 10–4. Then the gauge factor is a. 2.0 b. 3.0 c. 4.0 d. 100 V Integrating principle in the digital measurement is the conversion of a. Voltage to time b. Voltage to frequency c. Voltage to current d. Current to voltage The correct sequence of the blocks is an analog data acquisition unit starting from the input is a. Transducer - Recorder Signal Conditioner

15 of 15

115.

116.

b. Transducer - Signal - Conditioner Recorder c. Signal - Conditioner - Transducer Recorder d. Signal - Conditioner - Recorder Transducer Which one of the following effects in the system is NOT caused by negative feedback? a. Reduction in gain b. Increase in bandwidth c. Increase in distortion d. Reduction in output impedance Match List I (Block Diagram) with List II (Transformed Block Diagram) and select the correct answer : List I A.

c. d.

117.

3 4

4 3

1 2

2 1

The gain C(s) / G(s) of the signal flow graph shown above is G1G2 + G2G3 a. 1 + G1G2 H + G2G3 H1 + G4 b.

G1G2 + G2G3 1 + G1G2 H1 + G2G3 H1 − G4

c.

G1G3 + G2G3 1 + G1G3 H1 + G2G3 H1 + G4

d.

G1G2 + G2G3 1 + G1G3 H1 + G2G3 H1 − G4

118.

B. C (s) R( s) diagram shown above is G1G2 a. 1 − G1G2 H1 H 2

The overall gain C.

D.

List II 1.

G1G2 1 − G2 H 2 − G1G2 H1

c.

G1G2 1 − G2 H 2 + G1G2 H1 H 2

G1G2 1 − G1G2 H1 − G1G2 H 2 The unit impulse response of a second order system is 1/6 e–0.8t sin (0.6 t). Then the natural frequency and damping ratio of the system. are respectively a. 1 and 0.6 b. 1 and 0.8 c. 2 and 0.4 d. 2 and 0.3 A second order control system has 100 M ( jω ) = 100 − ω 2 + 10 2 jω Its Mp (Peak magnitude) is a. 0.5 b. 1 2 c. d. 2 d.

119. 2.

3. 120. 4.

a. b.

b.

A 3 4

B 4 3

C 2 1

D 1 2

of the block

I.E.S. (OBJ) - 2004

1 of 16

ELECTRICAL ENGINEERING PAPER–I 1.

2.

What is the force experienced per unit length by a conductor carrying 5 A current in positive Z direction and placed in a magnetic field B = ( 3ax + 4a y ) ? r r a. 15ax + 20a y N / m r r b. −20ax + 15a y N / m r r c. 20ax − 15a y N / m r r d. −20ax − 20a y N / m

Plane z = 10 m carries surface charge density 20 nc/m2. What is the electric field at the origin? a. −10aˆ z v / m

5.

electric field exists at z ≥ 0 as E1 = 5aˆ x − 2 aˆ y + 3aˆ z kw/m. What is the value of E2 in the region z ≤ 0? a. 3aˆ z b. 5aˆ x − 2aˆ y c. 6aˆ z d. aˆ x − aˆ y 6.

b. −18π az v / m c. −72π aˆ z v / m d. −360π aˆ z v / m 3.

Consider the following diagram: 7.

4.

Which of the following statements is correct? The electric field E at a point P due to the presence of dipole as shown in the above diagram (considering distance r >> distance d) is proportional to a. 1/r b. 1/r2 c. 1/r3 d. 1/r4 What is the value of total electric flux coming out of a closed surface? a. Zero b. Equal to volume charge density c. Equal to the total charge enclosed by the surface d. Equal to the surface charge density

Two extensive homogenous isotropic dielectrics meet on a plane z = 0. for z ≥ 0, ε r1 = 4 and for z ≤ 0, ε r2 = 2 uniform

8.

What will be the reflected wave for an elliptically polarized wave incident on the interface of a die-electric at the Brewester angle? a. Elliptically polarized b. Linearly polarized c. Right circularly, polarized d. Left circularly polarized A flat slab of dielectric, ε r = 5 is placed normal to a uniform field with a flux density D = 1 Coulomb/m2. The slab is uniformly polarized. What is the polarization P of the slab in Coulomb/m2? a. 0.8 b. 1.2 c. 4 d. 6 Which one of the, following gives the approximate value of the capacitance between two spheres, whose separation is very much larger than their radii R? a. 2π / ε 0 R b. 2 π ε 0 R c. 2 π ε 0 / R d. 4 π ε 0 / R

9.

Which one of the following is the correct electromagnetic wave equation in terms of vector potential A?

a. ∇ 2 A −

∂ A = −J ∂t 2

b. ∇ 2 A −

μ ∂2 A = −μ J ε ∂t 2

c. ∇ 2 A −

∂2 A = −μ J ∂t 2

2

∂2 A = −μ j ∂T 2 Which one of the following statements is correct? The wavelength of a wave propagating in a wave guide is a. Smaller than me free space wavelength b. Greater than the free space wavelength c. Directly proportional to the group velocity. d. Inversely proportional to the phase velocity Which one of the following statements is correct? For a lossless dielectric medium, the phase constant for a traveling wave, β is proportional to a. ε r

13.

d. ∇ 2 A − με

10.

11.

a. b. c. d. 14.

ε c. 1/ ε r

b.

Match List I with List II and select the correct answer using the codes given below: List I A. Continuity equation B. Ampere’s law C. Displacement current D. Faraday’s law List II ∂D 1. ∇ × H = J + ∂t ∂D 2. J = ∂t ∂B 3. ∇ × E = − ∂t ∂l 4. ∇.J = − v ∂t

2 1 4 8

Match List I (Type of field denoted by A ). with List II (Behavior) and select the correct answer using the codes given below: List I A. A static electric field in a charge free region B. A static electric field in a charged region C. A steady magnetic field in a current carrying conductor D. A time-varying electric field in a charged medium with time-varying magnetic field List II 1. ∇A = 0

d. 1/ ε r 12.

2 of 16 A B C D a. 4 3 2 1 4 1 2 3 b. c. 2 3 4 1 2 1 4 3 d. In a lossless medium the intrinsic impedance η = 60π and μr = 1 . What is the value of the dielectric constant ε r ?

∇× A ≠ 0 2. ∇. A ≠ 0

∇× A = 0 3. ∇. A ≠ 0

∇× A ≠ 0 4. ∇. A = 0

15.

∇× A = 0 A B C D 4 2 3 1 a. 4 2 1 3 b. c. 2 4 3 1 2 4 1 3 d. Which one of the following statements is correct? A wave guide can be considered to be analogous to a a. Low pass filter

16.

17.

18.

19.

b. High pass filter c. Band pass fitter d. Band stop filter Consider the following statements about the effective length of a half wave dipole (Elevation angle θ is measured from the dipole axis) 1. Effective length is a function of θ . 2. Effective length is maximum for θ =π / 2. 3. Maximum effective length is larger than physical length. 4. Effective length is the same for the antenna in transmitting and receiving modes. Which of the statements given above are correct? a. 1, 2 and 4 b. 2, 3 and 4 c. 1, 2 and 3 d. 1, 3 and 4 A lossless transmission line of length 50 cm with L = 10μ H / m C = 40 pF/m is operated at 30 MHz. What is its electric length ( β l ) ? a. 20 λ b. 0.2 λ c. 108° d. 40 π Which one of the following statements is correct? If the Fermi level ties midway between the conduction and valence bands, then the semiconductors a. Intrinsic b. Extrinsic c. p-type d. n-type Which one of the following statements is correct? Superconductors are popularly used for a. Generating very strong magnetic field b. Reducing i2R losses c. Generating electrostatic field d. Generating regions free from magnetic field

20.

3 of 16 Which one of the following is the correct expression for the propagation constant in a transmission line? a.

21.

22.

23.

( R − jω L )( G − jωC )

b.

( R + jω L ) ( G − jωC )

c.

( R + jω L ) ( G + jωC )

d.

( R + jω L )( G + jωC )

On which of the following factors does the value of critical current density in a superconductor depend? a. Temperature b. Applied magnetic field c. Temperature and applied magnetic field d. Silsbee’s rule Match List I (Materials) with List Il (Equation/rule) and select the correct answer using the codes given below: List I A. Dielectric material B. Ferromagnetic material C. Conductors D. Superconductor List II 1. Debye equation 2. Curie Weiss law 3. Matthiessen’s rule 4. Meissner effect A B C D A B C D 3 4 1 2 a. 1 4 3 2 b. c. 3 2 1 4 1 2 3 4 d. A dielectric material has the real part of the dielectric constant ( ε r ) as 4 and its loss tangent is 0.004. What is the complex dielectric constant ( ε r *) represented by? a. b. c. d.

4 + j 0.016 4 – 0.016 4 + j 0.001 4 – j 0.001

24.

Match List I with List II and select the correct answer using the codes given below: List I A. Larmon frequency B. Bohr magnetron C. Magnetic induction D. Curie-Weiss law List II 1. χ = C / (T − θ )

31.

4 of 16 2. Alnico 3. Perm alloy 4. Ga As A B C D 3 1 2 4 a. 1 3 2 4 b. c. 3 1 4 2 1 3 4 2 d. Which one of the following statements is correct? A ferrite core has lower specific eddy current loss compared to an iron core because the iron core has a. Higher electrical resistance b. Lower electrical resistance c. Higher permeability d. Lower permeability In which one of the following ways can the Hall voltage across an impurity semiconductor crystal be increased? a. By increasing the thickness of the crystal b. By increasing the concentration of impurity atoms in the crystal c. By increasing the width of the crystal d. By increasing the current flowing through the crystal Which one of the following statements is correct? The Hall coefficient of an intrinsic semiconductor is a. Positive b. Negative c. Zero d. Infinite Consider the following circuit:

32.

Which one of the following statements is correct? The circuit shown above is a. Passive and linear b. Active and linear c. Passive and non-linear d. Active and non-linear Consider the following circuit:

28.

2. B = μ0 ( H + M ) 3. eh / 4π m

25.

26.

27.

4. eB/2m A B C D 2 1 4 3 a. 2 3 4 1 b. c. 4 1 2 3 4 3 2 1 d. Which one of the following statements is not correct? a. Vacuum can act as a dielectric material b. Piezoelectric, materials can act as transducers c. Quartz crystal is a ferroelectric material d. The dielectric constant of diectrics depends on the frequency of the applied field Which one of the following is the temperature below which certain material are ant ferromagnetic and above which they are paramagnetic? a. Curie temperature b. Neel temperature c. Transition temperature d. Weiss temperature Match List I (Type of the material) with List II (Name of the material) and select the correct answer: List I A. Ferromagnetic B. Soft magnetic C. Hard magnetic D. Semiconductor List II 1. Rochelle salt

29.

30.

5 of 16

33.

34.

35.

In the above circuit, when Vs = 3V , I = 4 A , what is the value of I when Vs = 12V? a. 5 A b. 10 A c. 15 A d. 20 A Three parallel resistive branches are connected across a. d.c. supply. What will be the ratio of the branch currents I1:I2:I3 if the branch resistances are in the ratio R1 : R2 :R3::2:4:6? a. 3 :.2 : 6 b. 2:4:6 c. 6:3:2 d. 6:2:4 Consider the following circuit:

What is the value of current I in the 5Ω resistor in the above circuit? a. 0A b. 2A c. 3A d. 4A A voltage source having an internal impedance of 8 + j6 ohms supplies power to a resistive load. What should be the load resistance for maximum power transferred to it? a. 8 ohms b. 6 ohms c. 10 ohms d.

36.

37.

a. 3A, 40Ω b. 4A, 24Ω c. 1A,60Ω d. 2A,100Ω Consider the following circuit:

38.

What is the value of current I in the above circuit? a. 1 A b. 2 A c. 3 A d. 4 A Consider the following circuit:

39.

a. e − t b. 2e−3t c. 3e−3t

10 ohms

Consider the circuits A and B given below:

For what values respectively of I and R, the circuit B is equivalent to circuit A?

What should be the value of resistance R, in the above circuit if it has to absorb the maximum power from the source? a. 8/3 ohms b. 3/8 ohms c. 4 ohms d. 8 ohms The transfer function of a system V (s) s . The system is at rest Z (s) = = I (s) s + 3 for the t < 0. What will be the value of v(t) for t ≥ 0, if i(t) = 3u(t) , where u(t) is a unit step?

40.

d. 4e − t Consider the following circuit:

For the circuit shown above, by how much the voltage across the inductor leads the voltage across the capacitor?

41.

42.

a. 45° b. 90° c. 135° d. 180° Consider the following circuit:

The circuit shown above is in steady state before closing the switch. What is the current i(o+) through the switch if the circuit is closed at t = 0? a. – 4A b. 0 A c. 4 A d. 12 A Consider the following circuit:

44.

45.

46.

43.

The circuit shown above attains a steady state with the switch S closed. What is the value of 1(t) for t ≥ 0, if the switch S is opened at t = 0? a. 0.5+0.5 e–50t b. 0.6–0.1e–50t c. 0.5–0.5e–50t d. 0.6–0.6e–20t Consider the following diagram:

47.

6 of 16 Consider the following pole-zero diagram of a system function Z(s) = V(s)/I(s).

What will be the magnitude of the voltage phasor for i(t) = sin t? a. 3/2 b. 1 c. 2/3 d. 1/3 A balanced delta connected load has an impedance of 9∠30° ohms per phase. What is the impedance per phase of its equivalent star? a. 27 ∠30°Ω b. 27 ∠90°Ω c. 3 ∠30°Ω d. 3 ∠20°Ω For a parallel RLC resonant circuit; the damped frequency is 8 r/s and bandwidth is 2 r/s. What is its resonant frequency? a. 2 b.

7

c.

10

d. 3 Consider the following circuit:

In the above circuit Z ( s ) = 2 as s → ∞

Which one of the following gives Lap lace transform of the wavelength v(t) shown in the above diagram? a. ⎡⎣e s + e2 s + 2e3s ⎤⎦ / s b. ⎡⎣e s + e2 s − 2e3s ⎤⎦ / s c. ⎡⎣e− s + e−2 s − 2e −3s ⎤⎦ / s d. ⎡⎣e− s + e−2 s + 2e −3s ⎤⎦ / s

48.

and Z (s) = 3 as s → 0 . What are, respectively the values of R1 and R2? a. 6Ω, 3Ω b. 4Ω, 2Ω c. 3Ω, 6Ω d. 6Ω, 2Ω Consider the following circuit:

49.

50.

For the above circuit, the current source is sinusoidal with frequency equal to the resonant frequency of the circuit. What is the value of current through the resistor? a. 0 b. 0.1 I c. I d. 10 I In an a.c. series RLC circuit, the voltage across R and L is 20 V, voltage across L and C is 9V and voltage across RLC is 15V. What is the voltage across C? a. 7V b. 12V c. 16V d. 21V Consider the following circuit:

53.

shown in the circuit given below:

54.

51.

What is the short-circuit natural frequency at port 1 of the above circuit? a. S + 2 = 0 b. S + 1 = 0 c. 2s + 1= 0 d. 2s + 3 = 0 Two resistors of equal value are connected in series across the lines B and C of a symmetrical 3-phase 400 – V system. What is the magnitude of the voltage between the line A and the junction of the resistors?

55.

a. 400 / 3 b. 200 3 c. 400 / 3 d. 100 3 52.

Two identical T-sections, such as one shown below are connected in series.

What is the y11 of the combination? a. 11/240 b. 22/240 c. 11/360

7 of 16 d. 22/120 The realization of the driving points impedance function 2 2 Z ( s ) = (α s + 7 s + 3) / ( s + 3s + β ) is

56.

What are, respectively the values of α and β? a. 5,2 b. 2,5 c. 2,3 d. 2,1 Impedance Z ( s ) = ⎡⎣( s + 3)( s + 5 ) ⎤⎦ / ⎡⎣( s + 4 )( s + 6 ) ⎤⎦ is realized in the Foster’s second form. What will be the values, respectively of R and L in one of the series R-L branches? a. 2Ω, 1/3 H b. 2Ω, 4/3 H c. 2Ω, 5/3H d. 2Ω, 2/3H Match List I (Accuracy) with List II (Type of the standard) and select the correct answer: List I A. Least accurate B. More accurate C. Much more accurate D. Highest possible accurate List II 1. Primary 2. Secondary 3. Working 4. International A B C D a. 3 4 1 2 1 4 3 2 b. 3 2 1 4 c. 1 2 3 4 d. Which one of the following statements is correct?

57.

58.

59.

60.

61.

The application of the instrument in wrong manner in the procedure of measurement results in a/an a. Systematic error b. Random error c. Gross error d. Instrument error A 0 to 200 V voltmeter has a guaranteed accuracy of 1% of full scale reading. The voltage measured by this instrument is 50 V. What is the limiting error? a. 4% b. 2% c. 1% d. 0.25% Which one of the following statements correctly represents the systematic errors? a. These errors can be calculated from the details of the instruments b. These are the residual errors c. These errors may occur under controlled conditions d. These are the errors committed by the experiments A resistor R is measured using the V-I method, with V read as 10.14 V and I as 5.07 mA. Which one of the following expresses the value of resistance? a. 2 kΩ b. 2.00 kΩ c. 2000Ω d. 2.0 kΩ Which one of the following statements is correct? The deflection of hot wire instrument depends on a. r.m.s. value of the a.c. current b. r.m.s. value of the a.c. voltage c. average value of the a.c. current d. average value of the a.c. voltage Which one of the following materials is used in the fabrication of swamping resistance of a PMMC instrument? a. Copper b. Aluminium c. Manganin d. Tungsten

62.

63.

64.

65.

66.

67.

8 of 16 Which one of the following is basically a current sensitive instrument? a. Permanent magnet moving coil instrument b. Cathode ray oscilloscope c. Electrostatic instrument d. FET input electronic voltmeter A d’Arsonval movement with internal résistance R = 100 Ω and full scale current of 1I mA is to be converted into (0 - 10) V range. What is the required resistance? a. 10 Ω b. 10100 Ω c. 9900 Ω d. 12000 Ω Which one of the following types of instruments can be used to determine the r.m.s. value of a.c. voltage of high magnitude (10 kV) and of any wave shape? a. Moving iron instruments b. Dynamometer type instruments c. Induction instruments d. Electrostatic instruments The battery cells in an electronic millimeter are required to measure which one of the following? a. Resistance b. Voltage c. Current d. Power Which, one of the following methods decreases the error due to connections in a dynamometer type Wattmeter? a. Using bifilar compensating Winding in place of current coil b. Using non-inductive pressure coil circuit c. Using a capacitor across a part of high resistance of pressure coil circuit d. Using a swamping resistance The power of a three-phase, three-wire balance system was measured by twoWattmeter method. The reading of one of the Wattmeters was found to be double that of the other. What is the power factor of the system? a. 1

68.

69.

70.

71.

b. 0.866 c. 0.707 d. 0.5 Match List I with List II and select the correct answer using the codes given below: List I (Instruments) A. Dynamometer instrument B. Thermocouple based instrument C. Ramp generator D. Weston Standard Cell List II (Application) 1. True r.m.s. value mete 2. Transfer instrument between a.c. and d.c. 3. Time base of CRO 4. Standard of Electromotive force (Emf) Codes; A B C D a. 4 1 3 2 b. 4 3 1 2 2 1 3 4 c. 2 3 1 4 d. Low resistance from few ohms down to one micro ohm is measured using which one of the following instructs merits? a. Ohmmeter b. A series type ohmmeter c. A shunt type ohmmeter d. A voltmeter and an ammeter Which one of the following statements is correct? An electronic voltmeter is more reliable as compared to multimeter for measuring voltage across low impedance because a. its sensitivity is high b. it offers high input impedance c. it does not alter the measured voltage d. its sensitivity, and input impedance are high and do not alter the measured value Which one of the following decides the precision of integrating digital voltmeter? voltage of analog a. Reference comparator b. Slope of the generated ramp c. Width of the generated pulses

72.

73.

74.

75.

76.

77.

9 of 16 d. Electronic counter Which one of the following statements is correct? Spiral springs are used in instruments to a. provide controlling torque b. provide damping torque c. lead the current to moving coil as well as to provide the controlling torque d. provide linear deflection Which one of the following decides the time of response of an indicating instrument? a. Deflecting system b. Controlling system c. Damping system d. Pivot and Jewel bearing Which one of the following is measured by the loss of charge method? a. Low R b. High R c. Low L d. High L Which one of the following gives Gauge factor of a strain gauge? ΔL ΔR a. L R ΔR ΔL b. R L ΔR ΔD c. R D ΔR Δρ d. ρ R Which one of the following definition correctly, represents a data acquisition system (DAS)? a. DAS is a group of electronic devices that are connected to perform the measurement and quantization of electrical Signals for digital processing b. DAS is a group of devices that are connected t store different signals c. DAS is a system to control a process d. DAS is a signal conditioner Match List I with List II and select the correct answer using the codes given below List I (Transducer)

78.

79.

80.

A. Piezo-electric crystal B. Manometer C. Resistance bridge D. Resistance strain gage List II (Parameter) 1. Static pressure measurement 2. Dynamic force measurement 3. Study of vibration of a cantilever 4. Vibration in position of slider by an external force changes the resistance Codes; A B C D 4 1 2 3 a. 4 3 2 1 b. 2 1 4 3 c. 2 3 4 1 d. Which one of the following thermocouples has the highest temperature measuring range? a. Copper-Constantan b. Iron-Constantan c. Alumel-Chromel d. Platinum Rhodium-Platinum Consider the following elements: 1. Low pass filter 2. Signal transmission medium 3. Amplifier 4. Digital to analog convertor 5. Analog to digital convertor Which one of the following sequences is the correct sequence for effective signal re-construction in a data acquisition and processing scheme? a. 1-3-5-2-4 b. 3-1-5-2-4 c. 1-5-3-2-4 d. 3-5-1-4-2 Consider the following diagram:

10 of 16 For the multiple gear system shown above, which one of the following gives the equivalent inertia referred to shaft 1? a.

2

2

2

2

⎛NN ⎞ ⎛N ⎞ J1 + J 2 ⎜ 1 ⎟ + J 3 ⎜ 1 2 ⎟ ⎝ N2 ⎠ ⎝ N3 N 4 ⎠

2

2

2

2

⎛N ⎞ ⎛NN ⎞ J1 + J 2 ⎜ 1 ⎟ + J 2 ⎜ 1 3 ⎟ ⎝ N2 ⎠ ⎝ N2 N4 ⎠

⎛N N ⎞ ⎛N ⎞ b. J1 + J 2 ⎜ 2 ⎟ + J 3 ⎜ 2 4 ⎟ ⎝ N1 ⎠ ⎝ N1 N 3 ⎠ c.

81.

⎛NN ⎞ ⎛N ⎞ d. J1 + J 2 ⎜ 2 ⎟ + J 3 ⎜ 1 2 ⎟ ⎝ N1 ⎠ ⎝ N3 N 4 ⎠ Consider the following mechanical system shown in the diagram:

Which one of the following circuits shows the correct force- current analogous electrical circuit for the mechanical diagram shown above? a.

b.

c.

d.

82.

The signal flow graph for a certain feedback control system is given below:

Now consider the following set of equations for the nodes: 1. x2 = a1 x1 + a9 x3 2. x3 = a2 x2 + a8 x4

85.

11 of 16 Which one of the following statements is correct in respect of the above block diagrams? a. Only A and B are equivalent b. Only A and C are equivalent c. Only B and C are equivalent d. A, B and c are equivalent Consider the following three cases of block diagram algebra A, B and C

3. x4 = a3 x3 + a5 x2 4. x5 = a4 x4 + a6 x2

83.

Which of the above equations are correct? a. 1, 2 and 3 b. 1, 3 and 4 c. 2, 3 and 4 d. 1, 2 and 4 Consider the following system shown in the diagram:

In the system shown in the above diagram x(t) = sin t. What will be the response y(t) in the steady state? a. sin ( t − 45° ) 2 86.

b. sin ( t + 45° ) 2 c. 84.

2 e − t sin t

d. sin t − cos t Consider the following three diagram A, B and C shown below:

block

87.

Which of the above relations are correct? a. A and B b. B and C c. A and C d. A, B and C The damping ratio and natural, frequency of a second order system are 0.6 and 2 rad/s respectively. Which one of the following combinations gives the correct values of peak and setting time, respectively for the unit step response of the system? a. 3.33 S and 1.95 S b. 1.95 s and 3.33 S c. 1.95 s and 1.5 s d. 1.5 s and 1.95 S Match List I (Type of plots) with List VII (Functions) and select the correct answer using the codes given below: List I A. Bode plots B. Polar plots C. Nyquist plots D. Nichols chart List II 1. Open loop response due to damped sinusoidal inputs as a function of complex frequency

12 of 16

88.

2. Open loop response due to undamped sinusoidal as a function of real frequency 3. Closed loop response due to sinusoidal inputs as a function of real frequency 4. Open loop magnitude and phase angle responses for undamped sinusoidal inputs plotted separately as a function of real frequency Codes; A B C D 2 4 3 1 a. b. 2 4 1 3 c. 4 2 3 1 d. 4 2 1 3 A unity feedback control system has a forward loop transfer function as eTs Its phase value will be zero at ⎡⎣ s ( s + 1) ⎤⎦

1 1 2 + + b. (1 + K p ) Kv K a

91.

frequency ω1. Which one of the following equations should be satisfied by ω1? a. ω1 = cot (T ω1 ) b. ω1 = tan (T ω1 )

92.

c. T ω1 = cot (ω1 ) d. T ω1 = tan (ω1 )

89.

90.

Consider the following transfer functions: 1. 1/(S2+ S + 1) 2. 4/(S2 + 2S + 4) 3. 2/(S2 + 2S + 2) 4. 1/(S2 + 2S + 1) 5. 3/(S2 + 6S + 3) Which of the above transfer functions represent under damped second order systems? a. 4 and 5 b. 1, 4 and 5 c. 1, 2 and 3 d. 1, 3 and 5 Which one of the following equations gives the steady-state error for a unity feedback system excited by us ( t ) + t us ( t ) + ⎡⎣t 2us ( t ) / 2 ⎤⎦ a.

1 1 1 + + ( 2 + K p ) Kv Ka

93.

c.

1 1 1 + + K p Kv Ka

d.

1 1 1 + + (1 + K p ) Kv K a

A control system is defined in S-domain. Following points regarding the poles of the transfer function obtained from the characteristic equation were noted 1. Poles with positive real part denote stable system. 2. Complex poles always occur in pairs. 3. A pole S = - σ (σ > 0) means that the transient response contains exponential decay. Which of the above are correct? a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2 and 3 Consider the following statements regarding advantages of using the generalized error coefficients 1. The generalized error coefficients provide a simple way of determining the nature of the response of a feedback control system to almost any arbitrary input. 2. The generalized error coefficients lead to the calculation of the steady-state response without actually solving the system differential equation. 3. The generalized error coefficients establish relationships among the various types of inputs. Which of the above statements are correct? a. 1, 2 and 3 b. 1 and 2 c. 2 and 3 d. 1 and 3 The Nyquist plot for the closed-loop control system with the loop transfer 100 function G(S) H(S) = is S ( S + 10 ) plotted. Then, the critical point (-1, j0) is a. never enclosed

94.

95.

96.

b. enclosed under certain conditions c. just touched d. enclosed A minimum phase unity feedback system has a Bode plot with a constant slope of 20 db/decade for all frequencies. What is the value of the maximum phase margin for the system? a. 0° b. 90° c. - 90° d. 180° Consider the following Nyquist plot of a feedback system having open loop transfer function GH(s) = (S + 1)1 [s2(s - 2)] as shown in the diagram given below:

What is the number of closed loop poles in the right half of the s-plane? a. 0 b. 1 c. 2 d. 3 Consider the following statements for a counterclockwise Nyquist path: 1. For a stable loop system, the Nyquist plot of G(s)H(s) should encircle (-1, j0) point as many times as there are poles of G(s)H(s) in the right half of the splane, the encirclements, if there are any must be made in the counterclockwise direction. 2. If the loop gain function G(s)H(s) is a stable function, the closed loop system is always stable. 3. If the loop gain function G(s)H(s) is a stable function, for a stable closed-loop system, the Nyquist plot of G(s)H(s) must not enclose the critical point (-1, j0). Which of the statements given above is/are correct? a. Only 1 b. 1 and 2

97.

13 of 16 c. 1 and 3 d. Only 3 The characteristic equation for a thirdorder system is q ( s ) = a0 s 3 + a1s 2 + a2 s + a3 = 0

For the third-order system to be stable, besides that all the coefficients have to be positive, which one of the following has to be satisfied as a necessary and sufficient condition? a. a0 a1 ≥ a2 a3 b. a1a2 ≥ a0 a3 c. a2 a3 ≥ a1a0 98.

99.

100.

d. Only 3 A control system has G(s)H(s) = K/[s(s + 4)(s2 + 4s + 20)] (0 < K < ∞). What is the number of breakaway points in the root locus diagram? a. One b. Two c. Three d. Zero Which one of the following is the correct expression for the transfer function of an electrical RC phase-lag compensating network? RCS a. (1 + RCS ) b.

RC (1 + RCS )

c.

1 (1 + RCS )

d.

S (1 + RCS )

Which one of the following is not a correct reason to select feedback compensation over cascaded one? a. No amplification is required as the energy transfer is from higher to lower level b. Suitable devices are not available for compensation (series) c. It is economical d. Provides greater stiffness against load disturbances

101.

102.

103.

104.

For a unity feedback system, the origin of the s-plane is mapped in the z-plane by transformation z = eST to which one of the following? a. Origin b. 1 + j0 c. – 1 + j0 d. 0 + j1 Consider the following network:

What is the minimum number of states of the network given above in order to determine the complete output of the network over all future time for a given input? a. 0 b. 1 c. 2 d. 3 Match List I (Singular point) with List II (Phase portrait) and select the correct answer using the codes given below: List I A. Unstable focus B. Stable focus C. Stable node D. Saddle List II 1. A logarithmic spiral extending into the singular point 2. Trajectories approach singular point adjacent to straight line curve out and leave in vicinity of singular points 3. A logarithmic spiral extending out of the singular point 4. Trajectories are asymptotic to straight line Codes; A B C D a. 3 2 1 4 1 2 3 4 b. c. 3 4 1 2 1 4 3 2 d. About which one of the following is the phase-plane portrait for the non-linear

system

given

by

14 of 16 && x + f ( x, x& ) and

satisfying f ( x, x& ) = f ( − x, x& )

105.

106.

107.

symmetrical? a. x-axis b. x& -axis c. Both the x and x axes d. Neither x nor x axes A unity feedback non-linear control system’s plot for —1/N and G(jω) is shown in the diagram given below:

N is describing function of the non-linear device and G(s) is the transfer function of the linear plant. Which one of the following statements is correct? The limit cycle is a. stable b. unstable c. critically stable d. None of the above Match List I (Name of the Component) with List II (Type of the Component) and select the correct answer using the codes given below: List I A. Amplidyne B. Potentiometer C. Stepper motor D. AC Tacho-generator List II 1. Rate feedback element 2. Actuator 3. Servo amplifier 4. Error detector Codes; A B C D 3 2 1 4 a. 1 2 3 4 b. 3 4 2 1 c. 1 4 3 2 d. Consider the following statements:

108.

109.

1. Servomotors have lighter rotor as compared to ordinary motors and hence lower inertia. 2. Back e.m.f. in field controlled d.c. motors acts as minor loop feedback and results in increased damping and improved transient response. 3. Permanent magnet d.c. servomotors can be used in either armaturecontrolled or field-controller modes. Which of the above statements are not correct? a. 1 and 2 b. 2 and 3 c. 1 and 3 d. 1, 2 and 3 Match List I (Plot/Model) with List II (Related parameter) and select the correct answer using the codes given below: List I A. Root locus plot B. Bode plot C. Nyquist plot D. Signal flow chart List II 1. Comer frequency 2. Breakaway point 3. Critical point 4. Transmittance Codes; A B C D 4 3 1 2 a. 4 1 3 2 b. c. 2 3 1 4 2 1 3 4 d. A 3-phase star-connected balanced load consumes P watts of power from a 400 V (line to line voltage) supply. if the same load is connected in delta across the same supply, what is the power consumption ? a. P/13W b. P W c.

110.

111.

112.

113.

3PW

d. 3 P W Assertion (A): An intrinsic semi-conductor has low electrical conductivity. I-fence, it is normally not used in the device fabrication without damping.

114.

15 of 16 Reason (R): Its electrical resistivity can be increased by raising its temperature. a. Both A ‘and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the, correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): In a lossless transmission line the voltage and current distributions along the line are always Constant. Reason (R): The voltage and current distributions in an open line are such that at a distance λ/4 from the load end, the line looks like a series resonant circuit. a. Both A ‘and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the, correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): An electric or mechanical input makes the flux jump from one superconductor to another, generating large direct currents. Reason (R): The electric resistivity of superconductors depends upon the magnetic field. a. Both A ‘and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the, correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Cryotron is a switch constructed out of superconducting materials. Reason (R): Switching action is characteristic of superconductors only. a. Both A ‘and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the, correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Soft magnetic material is used in making electromagnets. Reason (R): Soft magnetic materials have a high coercive field.

115.

116.

117.

a. Both A ‘and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the, correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): If Thevenin’s equivalent of a circuit is known, its Norton equivalent is also known. Reason (R): Noton’s equivalent is reciprocal of Thevenin’s equivalent. a. Both A ‘and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the, correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): An electronic voltmeter measures the voltage across a high resistance more accurately as compared to an ordinary multimeter. Reason (R): The electronic voltmeter consists of a voltage amplifier which is not present in an ordinary multimeter. a. Both A ‘and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the, correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Cathode ray oscilloscopes using CRT employing electrostatic deflection are used in laboratories for scientific measurements. Reason (R): CRT using electrostatic deflection systems has more deflection sensitivity as compared to CRT employing magnetic deflecting system. a. Both A ‘and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the, correct explanation of A

118.

119.

120.

16 of 16 c. A is true but R is false d. A is false but R is true Assertion (A): A dual trace CR0 can display two input signals simultaneously. Reason (R): A dual trace CRO uses a CRT having two electron guns to generate two electron beams simultaneously. a. Both A ‘and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the, correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Data acquisition systems are used in a large and ever increasing number, of applications in a veriety of industrial and scientific areas. Reason (R): Transducer converts the analog signal to a form acceptable by the A/P convertor. a. Both A ‘and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the, correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): An addition of real zero at s = - z0 in the transfer function G(s) H(s) of a control system results in the increase of stability margin. Reason (R): An addition of real zero at s = - z0 in the transfer function G(s)H(s) will make the resultant root loci bend towards the left. a. Both A ‘and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the, correct explanation of A c. A is true but R is false d. A is false but R is true

I.E.S (OBJ)-2005

1 of 16

ELECTRICAL ENGINEERING PAPER–I 1.

2.

3.

4.

5.

A set of independent current measurements taken by four observers was recorded as: 117.02 mA, 117.11 mA, 117.08 mA and 117.03 mA. What is the range of error? a. ± 0045 b. ± 0054 c. ± 0065 d. ± 0056 The reference voltage and the input voltage are sequentially connected to the integrator with the help of a switch in a a. Successive approximation A/D converter b. Dual slope integration A/D converter c. Voltage to time converter d. Voltage to frequency converter A single channel digital storage oscilloscope uses a 12 bit, 108 samples/s ADC. For a 10 kHz sine wave input, what is the number of samples taken per cycle of input? a. 1012 b. 108 c. 104 d. 102 Consider the signal: Vm sin 100t + 2 Vm sin 200t to be sampled and stored in a data acquisition system. The same is to be extracted off-line later on. In order to extract the signal effectively, the original sampling frequency has to be a. 100 rad/s b. 200 rad/s c. 210 rad/s d. 1002 + 2002 rad/s Which one of the following transmission systems for telemetry has largest bandwidth? a. FM/FM radio transmission system

6.

7.

8.

b. Co-axial copper cables transmission system c. Fibre-optic data transmission system d. Synchro-position repeater system Why are dummy strain gauges employed? a. For calibration of strain gauges b. For increasing the sensitivity of the bridge c. For compensation of temperature variations d. For neutralizing the influence of bridge voltage supply variations Match List I (Type of DVM) with List II (Sub-component in ADC) and select the correct answer using the codes given below the lists: List I A. Ramp type B. Dual-slope C. Servo-type D. Successive approximation List II 1. DAC 2. Voltage to time converter 3. Pulse-generator 4. Potentiometer 5. Capacitor Codes; A B C D a. 2 1 4 5 b. 4 5 3 1 c. 2 5 4 1 d. 4 1 3 5 In modern electronic multi meter a FET or MOSFET is preferred over BJT because a. Its input resistance is low b. Its input resistance is high c. Its input resistance is high and does not vary with the change of range d. It is cheaper

9.

10.

11.

12.

Which of the following bridges can be used for inductance measurement? 1. Maxwell’s bridge 2. Schering bridge 2. Wein bridge 4. Hay’s bridge 3. Wheatstone bridge Select the correct answer using the codes given below a. 1 and 2 b. 2 and 3 c. 3, 4 and 5 d. 1 and 4 Match List I (Frequency) with List II (Detector) and select the correct answer using the codes given below the lists List I A. Zero frequency B. 50 Hz C. 1200 Hz D. 10 kHz List II 1. Head phone 2. D’Arsonval galvanometer 3. Cathode ray oscilloscope 4. Vibration galvanometer 5. Ballistic galvanometer Codes; A B C D a. 2 1 5 3 b. 3 4 1 2 c. 2 4 1 3 d. 3 1 5 2 Which of the following factors decide the accuracy in a bridge measurement? 1. Accuracy of the null indicator 2. Accuracy of the bridge components. 3. Sensitivity of the null indicator. 4. Applied voltage to the bridge system. Select the correct answer using the code given below a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 1 and 3 Match List I (Material Used in Instruments) with List II (Purpose) and select the correct answer using the code given below the lists:

13.

14.

2 of 16 List I A. Phosphor-bronze B. Manganin C. Aluminium D. Eureka List II 1. Coils 2. Discs 3. Control Springs 4. Shunts 5. Multipliers Codes; A B C D a. 3 5 2 4 b. 2 4 1 5 c. 3 4 2 5 d. 2 5 1 4 Match List I (type of Electronic Voltmeter) with List II (Major Characteristic) and select the correct answer using the code given below the lists: List I A. Amplifier-rectifier B. Rectifier-amplifier C. True R.M.S. D. Logarithmic List II 1. Wide input-signal dynamic range 2. High sensivity, limited bandwidth 3. Limited sensivity, large bandwidth 4. Capability to read non-sinusoidal ac Codes; A B C D a. 4 1 2 3 b. 2 3 4 1 c. 4 3 2 1 d. 2 1 4 3 What is the effect of inductance in the pressure coil on performance of a dynamometer type wattmeter? a. It reads low on lagging power factor and high on leading power factor b. It reads high on lagging power factor and low on leading power factor c. Its reading is not affected at all d. It always reads low

15.

16.

17.

18.

To measure 5 volts, if one selects a 0 - 100 volt range voltmeter which is accurate within ± 1%, then the error in this measurement may be up to a. ± 1.5% b. ± 2.5% c. ± 7.5% d. ± 20% Consider the following statements with regard to the bandwidth of a closed-loop system: 1. In systems where the low frequency magnitude is 0 dB h the Bode diagram, the bandwidth is measured at the -3dB frequency. 2. The bandwidth of the closed loop control system is a measurement of the range of fidelity of response of the system. 3. The speed of response to a step input is proportional to the bandwidth. 4. The system with the larger bandwidth provides slower step response and lower fidelity ramp response. Which of the statements given above are correct? a. 1, 2 and 3 b. 1, 2 and 4 c. 1, 3 and 4 d. 2, 3 and 4 Consider the following statements: A first order system with a proportional controller exhibits an offset to a step input. In order to reduce the offset, it is necessary to 1. Increase the gain of proportional controller. 2. Add a derivative mode. 3. Add an -integral mode. Select the correct answer using the code given below a. 1, 2 and 3 b. 1 and 2 c. 2 and 3 d. 1 and 3 Match List I (Nyquist Plot of Loop Transfer Function of a Control System) with List II (Gain Margin in dB) and select

19.

3 of 16 the correct answer using the code given below the Lists List I A. Does not intersect the negative real axis B. Intersects the negative real axis between 0 and (-1, jo) C. Passes through (-1, jo) D. Encloses (-1, jo) List II 1. > 0 2. ∞ 3. < 0 4. 0 Codes; A B C D a. 2 4 1 3 b. 3 1 4 2 c. 2 1 4 3 d. 3 4 1 2 Which one of the following is the steady state error of a control system with step error, ramp error and parabolic error constants kp, kv and ka respectively for the input (1 - t2) μ(t)? 3 3 a. − 1 + k p 2k a b.

3 6 + 1 + k p 2k a

c.

3 3 − 1 + k p 2k a

d.

3 6 − 1 + k p 2k a

20.

What is the overall transfer function of the block diagram given above? G1G2 + G2G3 a. 1 + G2 H1

b.

G1G2 + G2G3 1 + G3 H1

c. G1G2 + G2G3 d.

G1G3 + G2G3 1 + G2G3 H1

25.

21.

22.

For which of the following values of k, the feedback system shown in the above figure is stable? a. k > 0 b. k < 0 c. 0 < k < 42 d. 0 < k < 60 If the rotor axis of synchro transmitter is along the axis of S2 stator winding, when will be the electrical zeroing? a. VS1VS2 is maximum b. VS2VS3 is maximum c. VS2VS3 is minimum d. VS3VS1 is minimum

23.

The constant M-circles corresponding to the magnitude (M) of the closed loop transfer function of a linear system for values of M greater than one lie in the Gplane and to the a. Right of the M = 1 line b. Left of the M = l line c. Upper side of the M = ± j1 line d. Lower side of the M – j1 line

26.

24. 27.

Which one of the following is correct in respect of the figure given above? a. A and B are stable limit cycles b. A is stable limit cycle but B is unstable

4 of 16 c. A is unstable limit cycle but B is stable d. Both A and B are unstable Match List I (Specifications of Voltages to be Measured) with List II (Type of Most Suitable Instruments) and select the correct answer using the code given below the Lists: List I A. 0 - 10 mV from a source of internal resistance of 1. MΩ B. Thermo-emf ranging up to 5 mV from a thermocouple C. Supply voltage of 230 V, 50Hz D. R.M.S. value of a voltage containing dc and ripples of 50 Hz and harmonic List II 1. Thermal 2. Moving Iron 3. Permanent magnet moving coil 4. Electronic 5. Ballistic galvanometer Codes; A B C D a. 2 3 5 1 4 1 2 3 b. c. 2 1 5 3 4 3 2 1 d. What are the order and type of close-loop system for the plant transfer k and with unity function G ( s ) = 2 s (1 + Ts ) feedback? a. Two and two b. Three and two c. Two and zero d. Three and zero The open loop transfer function of a unity feedback control system is given by k . If gain k is increased to G (s) = s ( s + 1) infinity, then damping ratio will tend to become a. Zero b. 0.707 c. Unity d. Infinite

28.

29.

30.

31.

The characteristic equation of a control system is given by s(s + 4)(s2 + 2s + s) + k (s + 1) = 0 What are the angles of the asymptotes for the root loci for k ≥ 0? a. 60°, 180°, 300° b. 0°, 180°, 300° c. 120°, 180°, 240° d. 0°, 120°, 240° Encirclement of origin of 1 + G(s) plane corresponds to encirclement of a point in the -1 + G(s) plane, given by a. 1 + j0 b. 0 + j0 c. - 2 + j0 d. - 1 + j0 Consider the following statements regarding compensators used in control systems 1. For type-2 or higher systems, lag compensator is universally used to overcome the undesirable oscillatory transient response. 2. In case of lag-lead compensator, a lag and a lead compensator are basically connected in parallel. 3. The S-plane representation of the lead compensator has a zero closer to the origin than the pole. 4. A lag compensator improves the steady state behaviour of a system while nearly maintaining its transient response. Which of the statements given above are correct? a. 1, 2 and 3 b. 2, 3 and,4 c. 1 and 2 d. 3 and 4 The open loop transfer function of a feedback system has m poles and n zeros (m > n). Consider the following statements: 1. The number of separate root loci is m. 2. The number of separate root loci is n. 3. The number of root loci approaching infinity is (m - n). 4. The number of root loci approaching infinity is (m + n).

32.

33.

34.

5 of 16 Which of the statements given above are correct? a. 1 and 4 b. 1 and 3 c. 2 and 3 d. 2 and 4 Match List I (Name of the Control System Component) with List II (Use of the Component in Control System) and select the correct answer using the code given below: List I A. Amplidyne B. Potentiometer C. Stepper motor D. AC tacho-generator List II 1. Feedback element 2. Actuator 3. Control Amplifier 4. Error detector Codes; A B C D a. 3 1 2 4 2 4 3 1 b. 3 4 2 1 c. d. 2 1 3 4 The maximum temperature rise of a transformer is 50°C. It attains a temperature 31.6° in 1/2 hour. What is its thermal time constant? a. 2 hours b. 1/2 hour c. 1 hour d. 1/4 hour The state equations of a system are given by ⎡ −3 1 0 ⎤ ⎡0 ⎤ ⎢ ⎥ x& = ⎢ 0 −3 0 ⎥ x + ⎢⎢ 0 ⎥⎥ u ⎢⎣ 0 0 −1⎥⎦ ⎢⎣ 0 ⎥⎦ y = [1 0 1] x

The system is a. Controllable and observable b. Controllable but not completely observable

35.

36.

37.

c. Neither controllable nor completely observable d. Not completely controllable but observable In a speed control system, output rate feedback is used to a. Limit the speed of motor b. Limit the acceleration of the motor c. Reduce the damping of the system d. Increase the gain margin Consider the following equation: 2s4 + s3 + 3s2 + 5s + 10 = 0 How many roots does this equation have in the right half of s-plane? a. One b. Two c. Three d. Four Match List I (System) with List II (Transfer Function) and select the correct answer using the code given below: List I A. Lag Network B. AC Servomotor C. Field Controller dc servomotor D. Tacho-generator List II ⎛ 1 + aTs ⎞ 1. K ⎜ ⎟ ⎝ 1 + Ts ⎠

4.

K

s (1 + sτ m ) (1 + sτ f

List II 1.

Codes; a. b. c. d. 38.

C.

)

K s (1 + sτ m )

A 2 1 3 1

B.

D.

2. K1S 3.

39.

6 of 16 1. The natural frequency of the response is 6 rad/s. 2. The response is always oscillatory. 3. The percentage overshoot is 10% and damping ratio of the system is 0.6. 4. Both system time constant and settling time are infinite. Which of the statements given above are correct? a. 1 and 3 b. 2 and 4 c. 1, 2 and 3 d. 2, 3 and 4 Match List I (Original Diagram) with List II (Equivalent Diagram) and select the correct answer using the code given below the Lists List I A.

B 3 4 4 2

C 1 3 1 3

D 4 2 2 4

d2y + 36 y = 36 x dt 2 Consider the following statements in connection with the differential equation given above

2.

4

3.

4.

Codes;

40.

41.

42.

43.

44.

A B C D 3 1 4 2 a. 2 4 1 3 b. 3 4 1 2 c. 2 1 4 3 d. A 12 bit A/D converter has a range 0 - 10 V. What is the approximate resolution of the converter? a. 1 mV b. 2.5 mV c. 2.5 μV d. 12 mV Pulse code modulation is commonly used in telemetry because a. It ensures immunity from noise during transmission b. The bandwidth requirement of the channel is reduced c. It removes quantization error d. It permits lower rate of sampling than what is normally required under Shanon’s theorem A uniform plane wave has a wavelength of 2 cm in free space and 1 cm in a perfect dielectric. What is the relative permittivity of the dielectric? a. 2.0 b. 0.5 c. 4.0 d. 0.25 What are the materials which exhibit electric polarization even in the absence of an applied electric field called? a. Ferromagnetic b. Paramagnetic c. Ferroelectric d. Anti-ferroelectric The magnetic field at which a superconductor remains in its superconducting

45.

46.

7 of 16 state at a temperature less than the transition temperature is a. Zero b. Greater than the critical field corresponding to the given temperature c. Less than the critical field corresponding to the given temperature to the critical field d. Equal corresponding to the transition temperature Match List I (Response) with List II (Parameter) and select the correct answer using the codes given below the Lists: List I A. Swiftness of transient response B. Closeness of the response to the desired response C. Reduction of steady state error D. Number of integrators in loop transfer function List II 1. Feedback control 2. Type number 3. Rise time and peak time 4. Overshoot and settling time Codes; A B C D a. 3 4 1 2 b. 2 1 4 3 3 1 4 2 c. d. 2 4 1 3 Consider the following statements regarding magnetic materials: 1. Relative permeability of water is 0.99999 and that of oxygen is 1.00002; hence water is dia-magnetic and oxygen is para-magnetic material. 2. Ferrimagnetic material has no eddy current loss. 3. Permalloy and Alnico are two examples of hard magnetic materials. 4. The magnetisation and applied electric field in ferromagnetic materials are related non-linearly. Which of the statements given above are correct? a. 1, 2 and 3 b. 2, 3 and 4

47.

48.

49.

50.

51.

c. 1, 3 and 4 d. 1, 2 and 4 The systeresis loop for the material of the core of a transformer should be a. Short and narrow b. Tall and narrow c. Short and wide d. Tall and wide. All magnetic materials lose their magnetic properties when a. Cooled to low temperature b. Heated to high temperature c. Kept in an aluminium box d. Kept in vacuum The electrical conductivity of a semiconductor increases with increase in temperature because a. The mobility of the carriers increases b. The carrier concentration increases c. Both carrier concentration and mobility increase d. Thermal energy of electrons increases Match List I with List II and select the correct answer using the code given below the Lists: List I A. Non-linear system B. Linear system C. Time varying system D. Multiplication in S-domain List II of superposition and 1. Principle homogeneity and homogeneity 2. Describing function 3. Convolution integral 4. Rocket Codes; A B C D 1 2 3 4 a. b. 2 1 4 3 2 1 3 4 c. d. 1 2 4 3 Which one of the following is not a permanent magnetic material? a. Chromium steel b. Silicon iron c. Cobalt steel

52.

53.

54.

55.

56.

8 of 16 d. Alnico In metals, resistivity is composed of two parts: one part is characteristic of the particular substance. The other part is due to a. Applied voltage b. Crystal imperfections c. Applied magnetic field d. Supplied thermal energy Fermi level in a p-type semiconductor lies close to a. The top of the valence band b. The bottom of the valence band c. The top of the conduction band d. The bottom of the conduction band Above the Curie temperature, Ferromagnetic materials behave like a. Paramagnetic b. Diamagnetic c. Anti-ferromagnetic d. Ferromagnetic Match List I with List II and select the correct answer using the codes given below the Lists: List I A. Breakaway point B. Phase margin C. Gain margin D. Second order system List II 1. Stable 2. Phase cross-over frequency 3. Gain cross-over frequency 4. Root locus Codes; A B C D a. 4 3 2 1 4 3 1 2 b. c. 3 4 2 1 d. 3 4 1 2 In an analog data acquisition unit, what is correct sequence of the blocks starting from the input? a. Transducer — Recorder — Sgna1 conditioner b. Transducer — Signal conditioner — Recorder

57.

58.

59.

60.

c. Signal conditioner — Transducer — Recorder d. Signal conditioner — Recorder — Transducer Thermistors are essentially semiconductors a. Well suited to precision measurement of temperature b. Widely used in the lower temperature range of -100°C to 300°C c. Which behave as resistors with a high negative temperature coefficient of resistance d. All of the above Which one of the following frequency meter is suitable for measuring radio frequency? a. Vibrating reed frequency meter b. Weston frequency meter c. Electrical resonance frequency meter d. Hetrodyne frequency meter Which one of the following digital voltmeters is most suitable to eliminate the effect of period noise? a. Ramp type digital voltmeter b. Integrating type digital voltmeter c. Successive approximation type digital voltmeter d. Servo type digital voltmeter Match List I with List II and select the correct answer using the code given below the Lists: List I A. imaginary axis of S-plane B. Oscillatory time domain response C. Over damped time response D. Poles at origin of S-plane List II 1. Imaginary axis poles and S-plane 2. Type of the system 3. Unit circle of Z-plane 4. Poles on real axis of S-plane Codes; A B C D 1 3 4 2 a. b. 1 3 2 4 3 1 4 2 c. d. 3 4 1 2

61.

62.

63.

64.

9 of 16 Chopper stabilized d.c. amplifier type electronic voltmeter overcomes the effect of a. Amplifier CMRR b. Amplifier sensitivity c. Amplifier drift d. Electromagnetic interference Which of the following measurements can be made using Lissajous figures? 1. Frequency 2. Phase difference 3. Time interval between pulses 4. Pulse width 5. Fundamental and higher harmonic components. Select the correct answer using the code given below a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 4 and 5 Wagner Earth devices in AC bridge circuits are used for a. Shielding all the bridge elements from external magnetic field b. Eliminating the effect of stray capacitance c. Minimizing the effect of intercomponent capacitance d. Eliminating all the node to earth capacitances Which one of the following defects is responsible for creeping in an induction type energy meter? a. Imperfect lag compensation b. Over friction compensation c. Imperfect overload compensation d. Misalignment of brake magnet

65.

In the circuit given above, the steady state is attained with S open. S is closed at t = 0. What is the value of current I at t = 0+? a. 2 A

10 of 16 b. 2.25 A c. 3 A d. 4 A

d. 2 A 69.

66.

67.

For the a.c. circuit given above, what is the value of I? a. 1 + j1 b. 1 + j0 c. 2 – j1 d. 0 + j0 Match List I (Property of Network) with List II (Relevant Theorem) and select the correct answer using the code given below the Lists: List I A. Linearity B. Structure C. Equivalent Circuit D. Bilateral List II 1. Super position Theorem 2. Norton’s Theorem 3. Tellengen’s Theorem 4. Reciprocity Theorem 5. Millman’s Theorem Codes; A B C D a. 2 5 1 3 b. 1 3 2 4 2 3 1 4 c. d. 1 5 2 3

The black-box, N contains resistors and independent sources. If I = 3A and 1.5A for R = 0 and 2Ω, respectively, then what is the value of I for R = 1Ω? a. 1 A b. 2 A c. 3 A d. 4 A 70.

For the circuit shown above, sthe value of R is adjusted, so as to make the current in RL equal to zero. What is the a. 1 Ω b. 2 Ω c. 3 Ω d. 4 Ω 71.

68.

In the circuit given above, I = 1A for IS = 0. What is the value of I for IS = 2? a. 7 A b. 4 A c. 3 A

72.

For the circuit shown above, what is the voltage across the current source Is? a. 0 b. 2 V c. 3 V d. 6 V In an RLC series circuit, if the resistance R and the inductance L are kept constant but capacitance C is decreased, then which one of the following statements is/are correct? 1. Time constant of the circuit is changed. 2. Damping ratio decreases.

73.

3. Natural frequency increases. 4. Maximum overshoot is unaffected. Select the correct answer using the code given below a. 1 and 2 b. 2 only c. 2 and 3 d. 3 and 4 From the given list of driving point impedance functions, which one can be realized using R and C elements only ( s + 8) Z1 ( s ) = ( s + 2 )( s + 6 )

( s + 2 )( s + 6 ) ( s + 4) ( s + 4) Z3 ( s ) = ( s + 2) ( s + 2) Z4 ( s ) = ( s + 1)( s + 3) a. Z1 ( s ) b. Z 2 ( s ) c. Z 3 ( s ) d. Z 4 ( s )

76.

Z2 ( s ) =

77.

74.

11 of 16 List II 1. Ceramic capacitor 2. Piezoelectric application 3. Insulating materials for - machine windings 4. High frequency insulator Codes; A B C D a. 4 3 2 1 b. 2 1 4 3 c. 4 1 2 3 2 3 4 1 d. A 3-phasedelta-connected symmetrical load consumes P watt of power from a balanced supply. If the same load is connected in star to the same Supply, then what is the power consumption? a. P/3 b. P

c. 3 /P d. 3P A network has a zero at S = -1 and poles at S = - 4 ± j1, the multiplier being unity. If the input is α unit step function, then what is the steady state response? a. 2∠0° b. 1∠-45° c. 3∠90° d. 0.5∠0°

78.

75.

For the 2-port network shown in the figure given above, what is the value of the parameter h21? a. 1.5 b. -0.4 c. 0.6 d. -0.5 Match List I (Insulating Material) with List II (Application) and select the correct answer using the code given below: List I A. Steatite B. Rutile (Titanium dioxide) C. Barium titanate D. Teflon

What are the poles and zeroes of Z(s) of the above network? a. s = - 12, s = - 6 b. s = - 6, s = - 12 c. s = - 3, s = - 6 d. s = - 2, s = - 4 79.

12 of 16 B. Paramagnetic C. Ferromagnetic List II 1. ≈ 10+5 2. ≈ 10−5

80.

81.

82.

83.

A unit impulse voltage is applied at t = 0 to the R-L circuit shown above while i(0-) = 1 A. What is the expression for i(t)? a. e-10t b. 1.5 e-10t c. 2 e-10t d. 10 e-10t A circuit has two parallel branches. In one branch, R and L are connected in series while in the other; R and C are connected in series. If R = L / C , which one of the following is not correct? a. The circuit is in resonance b. The two branch currents are in quadrature c. The circuit has an impedance independent of its frequency d. The two branch currents are in phase Consider the following statements: 1. Buffer 2. Differentiator 3. Integrator 4. Comparator Which of the above is/are components in a dual slope integrating type voltmeter? a. 1, 3 and 4 b. 1 and 2 c. 3 and 4 d. 2 only Beam of electrons in a cathode ray tube eminates because of a. Second emission b. Thermionic emission c. Diffusion d. Post acceleration Match List I (Magnetic Material) with List II (Order of Susceptibility) and select the correct answer using the code given below the Lists: List I A. Diamagnetic

3. ≈ −10−5 Codes; A 1 a. b. 1 c. 3 3 d.

B 3 2 2 1

C 2 3 1 2

84.

Which one of the following gives the correct short circuit parameter matrix V for the network shown above? ⎡ 0.7 −0.5⎤ a. ⎢ ⎥ ⎣ −0.5 0.7 ⎦ ⎡ 0.7 −0.5⎤ b. ⎢ ⎥ ⎣ −0.5 0.8 ⎦

⎡ 0.8 −0.5⎤ c. ⎢ ⎥ ⎣ −0.5 0.7 ⎦ ⎡ 0.7 −0.5⎤ d. ⎢ ⎥ ⎣ 0.5 0.8 ⎦ 85.

For the two port network shown above, what is the voltage transfer function V2(s) / V1(s)? a. s/(1+2s2) b. s/(1+2s) c. 1/(1 + 2s2)

13 of 16 86.

d. 1/(1 +2s) For a series RLC resonant circuit, what is the total reactance at the lower half power frequency? a.

87.

88.

d.

2 R∠45°

2 R∠ − 45° b. c. R d. - R Match List I (Insulator) with List II (Application) and select the correct answer using the codes given below the Lists: List I A. Mica B. Polystyrene C. Porecelain D. Silicon rubber List II 1. Bushings 2. Electric wires and cables 3. Low voltage capacitors 4. Iron 5. Radio cabinets Codes; A B C D a. 4 5 1 2 b. 2 1 3 4 4 1 3 2 c. 2 5 1 4 d. The current behaviour in a circuit is expressed by: i(t) 2e −t − e −5t t ≥ 0 . Which one of the following figures shows the pole-zero pattern of I(s)? a.

89.

90.

91.

92. b.

c.

For the circuit shown above, the poles of the driving-point impedance function are at which one of the following locations? a. A pole at s = -2 b. A pole at s = -1 c. A double pole at s = -1 d. Poles at s = -1 and s -2 With the increase in frequency of in electromagnetic wave in free space, how do the velocity VC and characteristic impedance ZC change? a. VC increases and ZC decreases b. VC decreases and ZC increases c. Both VC and ZC increase d. Both VC and ZC remain unchanged The E field of a plane electromagnetic wave traveling in a non-magnetic nonconducting medium is given ur 9 by E = aˆ x 5cos (10 t + 30Z ) . What is the dielectric constant of the medium? a. 30 b. 10 c. 9 d. 3 In the wave equation ur ur ur ∂2 E ∂E 2 ∇ E = μ ∈ 2 + μσ ∂t ∂t Which term is responsible for attenuation of the wave? ur a. ∇ 2 E ur ∂2 E b. μ ∈ 2 ∂t ur ∂E c. μσ ∂t

14 of 16 93.

94.

95.

96.

97.

98.

99.

d. All of the above three Metallic copper is a a. Paramagnetic substance b. Diamagnetic substance c. Ferromagnetic substance d. Ferromagnetic substance The magnetic field required to reduce the residual magnetisation to zero is called a. Retentivity b. Coercivity c. Hysteresis d. Saturation magnetisation Bohr magneton is unit of a. Magnetic energy b. Permanent dipole moment due to spin c. Polarisability d. Hysteresis loss Magnetostriction is a phenomenon of a. Generation of electricity in ferromagnetic materials b. Generation of magnetism in conductors c. Change in permeability of ferromagnetic materials during magnetisation d. Change in physical dimensions of ferromagnetic materials during magnetisation Superconductivity is destroyed a. At high temperature b. At high magnetic field c. In presence of magnetic impurities d. In all the above cases Hall Effect can be used a. To find type of semiconductor (whether p or n type) b. To find carrier concentration c. To measure conductivity d. All of the above For electrostatic fields in charge free atmosphere, which one of the following is correct? ur ur a. ∇ × E = 0 and ∇.E = 0 ur ur b. ∇ × E ≠ 0 and ∇.E = 0 ur ur c. ∇ × E = 0 and ∇.E ≠ 0 ur ur d. ∇ × E ≠ 0 and ∇.E ≠ 0

100.

What is the value of the integral

∫

→

c

dl

along the curve c (c) is the curve ABCD in the direction of the arrow)? a. 2 R ( aˆ x + aˆ y ) / 2

b. −2 R ( aˆ x + aˆ y ) / 2 c. 2 Raˆ x d. −2 Raˆ y

101.

102.

Consider the following statements: 1. Poisson’s equation finds application in vacuum tube and gaseous discharge problems. 2. Gauss’s law is useful for determining field and potential distribution about bodies having unsymmetrical geometry. 3. For the propagation of electromagnetic waves, the time varying electric fields must support time varying magnetic fields. 4. The unit of Poynting’s vector is W/m2. Which of the statements given above are correct? a. l, 2 and 3 b. 1, 3 and 4 c. 2, 3 and 4 d. 1, 2 and 4 If the electric field established by three point ur charges Q, 2Qurand 3Q exerts a force 3 F on 3Q and 2 F on 2Q, then what is the force exerted on the point charge Q? ur a. F ur b. - F ur c. 5 F ur d. -5 F

15 of 16 103.

104.

105.

Which one of the following is not the valid expression for magneto static field ur vector B ? ur ur a. B = ∇. A ur ur b. B = ∇ × A ur c. ∇.B = 0 ur ur d. ∇ × B = μ0 J What is the value of standing wave Ratio (SWR) in free space for transmission coefficient Γ = −1/ 3 ? a. 2/3 b. 0.5 c. 4.0 d. 2.0 What is the phase velocity of plane wave in a good conductor? a.

π f μσ

b.

π fσ ( μσ )

c.

πf ( μσ )

d. 2 106.

108.

b. ∇. (∈ ∇V ) = − ρ c. ∇.∇ (∈ V ) = − ρ d. ∇ 2V = − ρ / ∈ 109.

110.

111.

What is the attenuation constant α for distortion less transmission line? a. α = 0 b. α = R

C L

c. α = R

L C

112.

c. 100/ 2 Ω d. 50 Ω A load impedance of (75 - j50) is connected to a transmission line of characteristic impedance Z0 = 75Ω. The best method of matching comprises a. A short circuit stub at load b. A short circuit stub at some specific distance from load c. An open stub at load d. Two short circuited stubs at specific distances from load When a lossless transmission line is terminated by a resistance equal to surge impedance, then what is value of the reflection coefficient? a. 1 b. -1 c. 0 d. 0.5 The instantaneous electric field of a plane wave propagating in z-direction is

E ( t ) = ⎡⎣ aˆ x E1 cos ωt − aˆ y E2 sin ωt ⎤⎦ e − jkz

RL C

A 50 Ω distortion less transmission line has a capacitance of 10-10 f/m. What is the inductance per meter? a. 0.25 μH b. 500 μH c. 5000 μH d. 50 μH Which one of the following is the Poisson’s equation for a linear and isotropic but inhomogeneous medium?

The open circuit and short circuit impedances of a line are 100 Ω each. What is the characteristic impedance of the line ? a. 100 2 Ω b. 100 Ω

πf ( μσ )

d. α = 107.

a. ∇ 2V = − ρ / ∈

113.

This wave is a. Linearly polarized b. Elliptically polarized c. Right hand circularly polarized d. Left hand circularly polarized Assertion (A): For a lossy transmission line, the voltage standing wave ratio (VSWR) is higher near the load end than that near the source end. Reason (R): In the presence of losses, the propagation constant of the line becomes a complex quantity. a. Both A and R are individually true and R is the correct explanation of A

114.

115.

116.

117.

b. Both A and R are true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The flux densities used in PMMC instruments vary from 0.1T to 1.0T. Reason (R): The power requirement for PMMC movement to give full scale deflection is small ranging from 25μW to 200 μW. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The variation in gain of the system does not alter the phase angle plot in the Bode diagram. Reason (R): The phase margin of the system is not affected by the variation in gain of the system. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Signal flow graphs can be used for block diagram reduction of linear control system. Reason (R): Signal flow graph is a graphical representation for the variables representing the outputs of the various blocks of the control system. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The PMMC type of indicating instruments are always critically damped. Reason (R): A critically damped system directly moves to its steady state without oscillation.

118.

119.

120.

16 of 16 a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): For a control system having synchro pair as error detector dc amplifier as control amplifier, a phase sensitive detector is required to demodulate in place of ordinary diode detector. Reason (R): Synchro output is a suppressed carrier amplitude modulated signal which cannot be demodulated by ordinary diode detector. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Skin depth is the depth by which electromagnetic wave has been increased to 37% of its original value. Reason (R): The depth of penetration of wave in a lossy dielectric increases with increasing wavelength. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): An insulator has a high value of resistivity, and with increasing temperature the value of its resistivity decreases exponentially. Reason (R): With increasing temperature, the value of the energy band gap decreases. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true

I.E.S-(OBJ) 2006

1 of 15

ELECTRICAL ENGINEERING PAPER-I 1.

2.

For a line of characteristic impedance Z0 terminated in a load of ZR such that ZR = Z0/ 3, what is the reflection coefficient ΓL? a. 1/3 b. —1/3 c. 2/3 d. —1/2 A transmission line has R, L. G, C distributed parameters per unit length of line. If γ is the propagation constant of the line, which one of the following expressions represents the characteristic impedance of the line? a. b. c.

6.

7.

γ

R + jω L R + jω L

γ G + jωC

γ

G + jωC R + jω L Impedance inversion may be obtained with a. a short-circuited stub b. an open-circuited stub c. a quarter-wave line d. a half-wave line When the temperature of a magnetic material is raised above the Curie point, it becomes a. diamagnetic b. paramagnetic c. ferromagnetic d. ferrimagnetic Soft iron is used in the manufacture of electromagnets because of its a. high saturation magnetisation only b. low retentivity only c. low coercive field only d. high saturation magnetisation, low retentivity and low coercive field

d.

3.

4.

5.

8.

With increase ‘in temperature, magnetic susceptibility of a ferromagnetic material will a. increase b. decrease c. increase, initially and then decrease d. remain constant Match List-I with List-II and select the correct answer using the code given below the Lists : List-I A. No eddy current loss B. Small hysteresis loss C. Large hysteresis loss List - II 1. Ferrimagnetic material 2. Soft magnetic material 3. Hard magnetic material 4. Non-ferrous material A B C a. 2 1 3 b. 2 3 4 1 3 4 c. d. 1 2 3 What is the packing fraction of a BCC (body-centered cubic) unit cell? a.

b. c.

3π 12

2π 8 The relative dielectric constant of solid dielectrics in the alternating field is a. maximum at the power frequencies and decreases to unity at frequencies in the ultraviolet range b. maximum at the power frequencies and decreases to zero at frequencies in the ultraviolet range

d. 9.

3π 16 3π 8

10.

11.

12.

13.

14.

15.

c. unity at the power frequencies and increases to its maximum value at frequencies in the ultraviolet range d. independent of frequency variations Width of energy bands depends on which of the following? a. Temperature b. Pressure c. Relative freedom of electrons in the crystal d. Mass of atom in the material Which one of the following statements is not true for a p-type semiconductor ? a. Conduction is by the movement of holes in the valence band b. Holes constitute the majority charge carriers c. Fermi level lies closer to the conduction band between the conduction and valence bands d. It is formed by adding an acceptor impurity to germanium Principle of Hall effect is used in the construction of which one of the following? a. Ammeter b. Voltmeter c. Galvanometer d. Gaussmeter For which one of the following materials, is the Hall coefficient zero ? a. Metal b. Insulator c. Intrinsic semiconductor d. Alloy What is the magnetic, susceptibility χ of an ideal superconductor ? a. 1 b. –1 c. 0 d. Infinite Assertion (A) : It is always desirable to take the reading of an indicating instrument very close to the full - scale reading. Reason (R) : Accuracy of an indicating instrument is maximum at the full-scale deflection and error increases as reading comes closer to the beginning of the scale. a. Both A and R are individually true and R is the correct explanation of A

16.

17.

18.

19.

2 of 15 b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The rotating disc in an energy meter is made up of a magnetic material. Reason (R) : Braking takes place due to eddy current generated by the braking magnet. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : A p-type GaAs sample can be converted to a semi-insulating substrate by doping it with chromium. Reason (R) : Chromium increases the band gap of GaAs. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : DC servomotors are more commonly used in armature controlled mode instead of in field controlled mode. Reason (R) : Armature controlled DC motors have higher starting torque than field controlled motors. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : General purpose dynamometer type Wattmeter cannot indicate the correct value of power at low power factors. Reason (R) : The presence of selfinductance in the pressure coil circuit introduces an error in the indicated value which increases appreciably with decrease in power factor. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A

20.

21.

22.

23.

c. A is true but R is false d. A is false but R is true Assertion (A) : With lag-lead compensation, the bandwidth of the system is not affected much. Reason (R) : The effect of lag and lead compensations at high frequencies cancel one another. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : For a stable feedback control system, the zeros of the characteristic equation must all be located in the left-half of the s-plane. Reason (R) : The poles of the closed-loop transfer function are the zeros of the characteristic equation. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : All the systems which exhibit overshoot in transient response will also exhibit resonance peak in frequency response. Reason (R) : Large resonance peak in frequency response corresponds to a large overshoot in transient response. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Superconductivity of a superconducting material can be destroyed by application of an external magnetic field. Reason (R) : If the applied magnetic field is greater than the critical magnetic field at a given temperature which is more than the transition temperature, superconductivity can be destroyed. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A

26.

3 of 15 c. A is true but R is false d. A is false but R is true A rectifier instrument is used to measure an alternating square wave, of amplitude 100 V. What is the meter reading? a. 100 V b. 70.7 V c. 111 d. None of the above For defining the standard metre, wavelength of which material is considered? a. Neon b. Krypton c. Helium d. Xenon Consider the following statements in connection with feedback in control system: 1. With an increase in forward gain, the output value approaches the input value in the case of negative feedback closed-loop system. 2. A negative feedback closed loop system when subjected to an input of 5 V with forward gain of 1 and a feedback gain of 1 gives output 4.999 V. 3. The transfer function is dependent only upon its internal structure and components, and is independent of the input applied to the system. 4. The overall gain of the block diagram shown is 10.

27.

Which of the statements given above are correct ? a. Only 1 and 2 b. Only 2 and 3 c. Only 3 and 4 d. Only 1 and 3 For a discrete-time system to be stable, all the poles of the Z-transfer function should lie a. within a circle of unit radius b. outside the circle of unit radius c. on left-half of Z-plane d. on right-half of Z-plane

24.

25.

28.

4 of 15 c. d. 33.

29.

30.

31.

32.

In the network shown above, what is the current I in the direction shown ? a. 0 b. 1/3 A c. 5/6 A d. 4 A With increase in applied frequency, the dielectric loss, in a material will a. increase b. decrease c. remain constant d. become zero Consider the network function : 2( s + 3) H ( s) = ( s + 2)( s + 4) What is the steady-state response due to a unit step input? a. 4/3 b. 1/2 c. 3/4 d. 1 What is the effect of phase lead compensator on gain crossover frequency (ωcg) and on the bandwidth (ωb) ? a. Both are increased b. ωcg is increased but ωb is decreased c. ωcg is decreased but ωb is increased d. Both are decreased Match List-I with. List-II and select the correct answer using the code given below the Lists : List-I A. Bolometer B. Hot-wire Anemometer C. C-type Bourdon Tube D. Optical Pyrometer List-II 1. Measurement of temperature of a furnace 2. Measurement of high pressure 3. Measurement of flow of air around an aeroplane 4. Measurement of power at 500 MHz 5. Measurement of angular position A B C D a. 2 3 5 1 b. 4 1 2 3

2 4

1 3

5 2

What is the range for a 3 a. b. c. d.

3 1

1 digital meter? 2

0 to 1999 0 to 1500 0 to 999 0 to 19999

34.

35.

36.

37.

Which one of the following is represented by the circuit shown above? a. DeSauty bridge b. Anderson bridge c. Heaviside-Campbell bridge d. Hay bridge What should be the main characteristic(s) of the null detector in a bridge measurement? 1. Accuracy 2. Precision 3. Sensitivity 4. Resolution Select the correct answer using the code given below : a. Only 1 and 2 b. Only 2 and 3 c. Only 3 and 4 d. Only 3 A moving-coil instrument gives full- scale deflection for I mA and has a resistance of 5 Ω. If a resistance of 0.55 Ω is connected in parallel to the instrument, what is the maximum value of current it can measure? a. 5 mA b. 10 mA c. 50 mA d. 100 mA A single slide wire is used for the measurement of current in a circuit. The voltage drop across a standard resistance of 1.0 Ω is balanced at 70 cm. What is the magnitude of the current, if the standard cell having an e.m.f. of 1.45 volts is balanced at 50 cm? a. 3.09 A b. 2.65 A c. 2.03 A

38.

39.

40.

41.

d. 1.45 A When reading is taken at half scale in the instrument, the error is a. exactly equal to half of full-scale error b. equal to full-scale error c. less than full-scale error d. more than full-scale error Match List-I with List-Il and select the correct answer using the code given below the Lists : List- I (Parameter to be measured) A. Average value of current B. QMS value of current C. Frequency of a wave D. Strain gauge resistance List-H (Instrument to be used) 1. Self-balancing bridge 2. Wien bridge 3. PMMC ammeter 4. Moving-iron ammeter A B C D a. 3 4 2 1 b. 2 1 3 4 c. 3 1 2 4 d. 2 4 3 1 Match List-I with List-II and select the correct answer using the code given below the Lists: List- I A. Digital Counter B. Schering Bridge C. Megger D. Spectrum Analyzer List-II 1. Measurement of harmonics 2. Measurement of frequency 3. Measurement of dielectric loss 4. Measurement of insulation resistance A B C D a. 1 3 4 2 b. 2 4 3 1 c. 1 4 3 2 2 3 4 1 d. Which of the following factors limit the deflection of the pointer of a PMMC instrument to about 90°? 1. Its damping mechanism 2. Linearity of the magnetic field in which the coil moves 3. Control spring arrangement

42.

43.

44.

45.

5 of 15 4. Shape of the polo shoe of the horseshoe magnet Select the correct answer using the code given below : a. Only 1 and 3 b. Only 2 and 4 c. Only 2 and 3 d. Only 1 and 4 Which of the following indicating instruments has/have linear scale ? 1. Moving-iron meter 2. Permanent magnet moving-coil meter 3. Thermocouple meter 4. Rectifier type meter Select the correct answer using the code given below: a. Only 1 and 2 b. Only 2 and 3 c. Only 3 and 4 d. Only 2 A sinusoidal voltage of 1 V r.m.s. value at 10 Hz is applied across the two terminals of a PMMC type of voltmeter. What is the deflection of the pointer? a. Zero volt b. 1 volt c. 2 volts d. The pointer oscillates around zero volt Match List-I with List-II and select the correct answer using the code given below the Lists : List- I (Instrument) A. A. PMMC voltmeter B. B. AC ammetor C. C. Current transformer D. D. Energy meter List-II (Error) 1. Eddy current error 2. Phase angle error 3. Braking system error 4. Temperature error A B C D a. 2 3 4 1 b. 4 1 2 3 2 1 4 3 c. d. 4 3 2 1 Maxwell’s inductance-capacitance bridge is used for measurement of inductance of a. 1ow Q coils only b. medium Q coils only c. high Q coils only

46.

47.

48.

49.

50.

d. low and medium Q coils Which one of the following statements does not state that electrostatic field is conservative? ur a. The curl of E is identically zero b. The potential. difference between two points is zero c. The electrostatic field is a gradient of a scalar potential d. The work done in a closed path inside the field is zero In free space, if ρ = 0, the Poisson’s equation becomes a. Maxwell’s divergence equation ∇.B=0 b. Laplacian equation V2 V = 0 c. Kirchhoff’s voltage equation ΣV 0 d. None of the above What is the magnetic field due to an infinite linear current carrying conductor? μI a. H = A/ m 2π r I b. H = A/ m 2π r μI A/ m c. H = 2r I d. H = A / m r ur Equation ∇.B = 0 is based on a. Gauss’s Law b. Lenz’s Law c. Ampere’s Law d. Continuity Equation Sphere of radius a with a uniform charge density pv C/m3 shall have electric flux density at r = a, equal to a ^ a. ρv i r C / m2 3 1 ^ b. ρv i r C / m 2 3 ^

c. a ρ v i r C / m

52.

53.

54.

55.

56.

^

density 30 k mA/m. At (1, 20, —2) what is the magnetic field intensity? ^

a. −15 i mA/m ^

b. 15 i mA/m ^

c. 18.85 j mA/m ^

57.

2

a ^ ρv i r C / m2 4 Which of the following is zero as applied to electromagnetic fields? ur a. grad div A b. div grad V ur c. div curl A ur d. curl curl A

d. 51.

6 of 15 Image theory is applicable to problems involving a. electrostatic field only b. magnetostatic field only c. both electrostatic and magnetostatic fields d. neither electrostatic nor magnetostatic field What is the force on a unit charge moving r with velocity v in presence of electric ur ur field E and magnetic field B ? ur r ur a. E − v.B ur r ur b. E + v.B ur ur r c. E + B × v ur r ur d. E + v × B Six capacitors of different capacitances C1, C2, C3, C4, C5 and C6 are connected in series. C1 > C2 > C3 > C4 > C5 > C6.What is the total capacitance almost equal to ? a. C1 b. C3 c. C4 d. C6 Where is the Laplace’s equation valid? a. Only in free space b. Only in conductors c. Only in charge free dielectric regions d. Only in cavities bounded on all sides by conducting walls Plane y = 0 carries a uniform current

58.

d. 25 i mA/m Equipotential surfaces about a pair of equal and opposite linear charges exist in what form? a. Concentric spheres b. Concentric cylinders c. Non-concentric cylinders d. Planes What does the function f(x—v0t) represent? a. A stationary wave b. A wave motion in a reverse direction

59.

60.

61.

62.

c. A wave motion in a forward direction d. Not a travelling wave The materials to be used in the manufacture of a standard resistance should be of a. high resistivity and low temperature coefficient b. low resistivity c. high temperature coefficient d. low resistivity and high temperature coefficient What is the Poynting’s vector on the surface of a long straight conductor of radius b and conductivity a which carries current I in the z-direction? I2 ^ ir a. − 2σπ 2b3 I2 ^ b. ir 2σπ 2b 2 I2 ^ iz c. σπ b 2 I ^ iφ d. 2π b Match List -I with List-II and select the correct answer using the code given below the Lists List - I (Material) A. Fe B. MnOFe2O3 C. MgOFe2O3 D. NiOFe2O3 List - II (Curie Temperature) 1. 783K 2. 523K 3. 863K 4. 1043K A B C D 2 3 4 1 a. 4 1 2 3 b. 2 1 4 3 c. d. 4 3 2 1 Consider the following statements regarding EM wave: 1. An EM wave incident on a perfect dielectric is partially transmitted and partially reflected. 2. An EM wave incident on a perfect conductor is fully reflected. 3. When an EM wave is incident from a more dense medium to less dense medium at an angle equal to or

63.

64.

65.

66.

67.

7 of 15 exceeding the critical angle, the wave suffers total internal reflection. Which of the statements given above are correct ? a. Only 1 and 2 b. Only 2 and 3 c. Only 1 and 3 d. 1, 2 and 3 In an intrinsic semiconductor, the number of electrons is equal to the number of holes at which temperature ? a. 0 K b. 0°C c. High temperature d. All temperatures Elements can reach a stable atomic structure by a. losing electrons only b. gaining electrons only c. losin or gaining or sharing electrons d. collisions between atoms The values of radiative and non-radiative lifetime of minority carriers in a semiconductor are 50 ns and 100 ns, respectively. What is the effective lifetime? a. 12.2 ns b. 150 ns c. 33.3 ns d. 75 ns Match List-I (Parameter) with List-II (Unit) and select the correct answer using the code given below the Lists : List- I A. Boltzman constant B. Permeability of free space C. Permittivity of free space D. Mobility List - II 1. farad/Metre 2. cm2/volt – second 3. henry/metre 4. cm2/second 5. electron volt/kelvin A B C D a. 5 2 1 4 1 2 5 4 b. c. 5 3 1 2 1 3 5 2 d. III-V alloy semiconductor crystallizes in what form?

8 of 15

68.

69.

a. Simple cubic structure b. Body-centered cubic structure c. Zinc blende structure d. Wurtzite structure Match List-I (Term) with List-II (Concept) and select the correct answer using the code given below the Lists : List-I A. Norton equivalent of one port B. Open-circuit output admittance C. Reciprocal network D. Transmission parameters List-II 1. Network where loop and mode equations have a symmetric coefficient matrix 2. Hybrid parameter h22 3. Parameters where V1 and I1 are expressed as functions of V2 and -I2 4. Current source in parallel with Thevenin impedance A B C D 1 3 4 2 a. 4 2 1 3 b. 1 2 4 3 c. 4 3 1 2 d. A system function has a pole at s = 0 and a zero at S - –1. The constant multiplier is unity. For an excitation sin t, what is the steady-state response ? 2 sin(t + 45o ) a. b.

In the circuit shown in the figure above, for what value of C will the current I be in phase with the sinusoidal source voltage Vs = sin2 t? 1 a. F 4 1 b. F 2 1 c. F 2 d. 1 F 72.

In the circuit shown in the figure above, if is = u(t) A, then what are the initial and steady-state voltages across the capacitor? a. 1 V and I V, respectively b. 1 V and 0, respectively c. 0 and I V. respectively d. 0 and 0, respectively 73.

2 sin(t − 45o )

c. sin(t − 45o ) d. sin t 70.

In the circuit shown above, the constant current source of value I is switched on at t = 0. What are the values of currents i1 and i2 at t = 0, with zero initial conditions ? i2 i1 I 0 a. 0 I b. R2 R2 I I c. R1 + R2 R1 + R2 0 0 d.

V (s) s + 3 = I (s) 4s + 5 The system is initially at rest. If the excitation i(t) is a unit step, which of the following are the initial and steady-state values of v(t)? Initial Value Steady-state value a. 0 3/5 0 b. 1/4 1/4 c. 3/5 3/5 d. 1/4 A system function N(s) =

71. 74. In the circuit shown in the figure given above, the switch is opened at t = 0 after

9 of 15

75.

having been closed for a long time. What is the current through 50 Ω resistor? a. 3e–1/160 t b. 3e–1/100 t c. 3e–100 t d. 3e–160 t Consider the following statements The gain cross-over point is the point where 1. the magnitude |G(jω)| = 1 in polar plot 2. the magnitude curve of G(jω) crosses zero dB line in Bode plot 3. magnitude vs phase plot touches the zero dB loci in Nichol’s chart Which of the statements given above are correct? a. Only 1 and 2 b. Only l and 3 c. Only 2 and 3 d. 1, 2 and 3

⎡0 [X ] = ⎢ ⎣ −1 y = x1 + x2 ⎡x ⎤ [ X ] = ⎢ x1 ⎥ ⎣ 2⎦

79.

76.

77.

78.

What is the open-loop transfer function for a unity feedback having root locus shown in the above figure? k ( s + 5) a. ( s + 1)( s + 2) k ( s + 1) b. ( s + 5)( s + 6) k c. s( s + 1)( s + 5) k ( s + 2) d. ( s + 1)( s + 5) The transfer function of a phase lead compensator is found to be of the form s + z1 and that of a lag compensator to be s + p1 s + z2 of the form s + p2 Then which of the following conditions must be satisfied? a. z1 > p1 and z2 > p2 b. z1 > p1 and z2 < p2 c. z1 < p1 and z2 < p2 d. z1 < p1 and z2 > p2 Given

80.

81.

82.

1⎤ ⎡0⎤ [ x] + ⎢ ⎥ u ⎥ 1⎦ ⎣k ⎦

What is the transfer y/x ? k ( s + 2) a. 3 s + 2s 2 + s + 1 k ( s + 2) b. 2 s + s +1 ks c. 2 s + 2s + 1 k d. 2 s + s +1 An electromechanical closed-loop control system has the transfer function C ( s) k 2 R( s ) s( s + s + 1)( s + 4) + k Which one of the following is correct? a. The system is stable for all positive values of k b. The system is unstable for all values of k c. The system is stable for values of k between zero and 3.36 d. The system is stable for values of k between 1.6 and 2.45. A particular control system yielded a steady-state error of 0.20 for unit step input. A unit integrator is cascaded to this system and unit ramp input is applied to this modified system. What is the value of steady-state error for this modified system? a. 0.10 b. 0.15 c. 0.20 d. 0.25 In order to recover the original signal from the sampled one, what is the condition to be satisfied for sampling frequency ω3 and highest frequency component ωm ? a. ωm < ωs ≤ 2ωm b. ωs ≥ 2ωm c. ωs < ωm d. ωs = ωm The characteristic equation of secondorder sampled date system is given by F(z) = a2z2 + a1z + a0 = 0. a2 > 0.

83.

84.

What are the stability constraints for this system ? 1. a2 + a1 + a0 > 0 2. a2 – a1 + a0 > 0 3. |a0| < a2 4. |a0| > a2 5. (a0) < a2 Select the correct answer using the code given below : a. Only 1, 2 and 3 b. Only l, 2 and 4 c. Only 1, 3 and 5 d. Only 2, 3 and 5 Consider the following statements : 1. For a linear discrete system to be stable, all the roots of the characteristic equation 1 + GH(z) = 0 should be inside the unit circle. 2. The Bode diagram of a sampled data system can be constructed using bilinear transformation. 3. The root locus technique can be used for sampled data system without requiring any modifications. Which of the statements given above is/are correct ? a. Only 1 b. Only 2 and 3 c. Only 1 and 3 d. 1, 2 and 3 Match List-I (Nature of Eigen value) with List-Il (Nature of Singular Point) and select the correct answer using the code given below the Lists: List-I A. Real, negative and distinct B. Real, equal but opposite in sign C. Purely imaginary pair D. Complex conjugate pair List-II 1. Centre 2. Focus point 3. Saddle point 4. Stable node 5. Unstable node A B C D a. 1 2 5 3 b. 4 3 1 2 c. 1 3 5 2 4 2 1 3 d.

85.

86.

87.

88.

10 of 15 Which one of the following statements is not related to limit cycles (phenomena) found in non-linear systems? a. They are oscillations of fixed amplitude and period b. They are undesirable. However, they can be tolerated if magnitude is within desirable limit c. They are independent of initial conditions d. Slight change in parameter, destroys the oscillation The effect of tachometer feedback in a control system is to reduce a. only time constant b. only gain c. damping d. both gain and time constant Match List-I (Application) with List-II (Control System Component) and select the correct answer using the code given below the Lists : List-I A. Measuring inclination of frames in inertial navigation system B. Used as an actuator element in computer printer C. For low power applications List- II 1. Gyroscope 2. Servometer 3. Stepper Motor 4. Schrage Motor A B C a. 2 3 4 1 4 2 b. c. 1 3 2 d. 2 1 4 Match List-I with List-II and select the correct answer using the code given below the Lists: List-I A. Synchros B. Operational amplifier C. Stepper motor D. Tacho-generator List-II 1. Controller 2. Error detector 3. Actuator 4. Feedback element A B C D

a. b. c. d.

3 2 3 2

1 4 4 1

2 3 2 3

11 of 15 3 /sin(ωt + 60°). What is the voltage v(t) across the 1Ω grounded resistor ? a. {cos ωt}V b. {sin (ωt + 300) + cos (ωt + 60°)}V c. {1∠90°)V d. {j l}V

4 1 1 4

89. 93.

For the feedback system shown in the figure above, which one of the following expresses the input-output relation C/R of the overall system G a. 1 − FG + GH G b. 1 + FG − GH FG c. 1 + FGH GH d. 1 − FGH

For the network shown as above, when I = 0, V = 20 V and when R = 0,I = 10A. If now R = 3 Ω, what is the value of the current I ? a. 6.67 A b. 6.0 A c. 4.0 A d. 10 A 94.

90.

91.

At t = 0, the switch k is thrown from b to a of the circuit as shown above. What are the values of v(0+) and i(0+)? a. 50 V,90 mA b. 50 V, 100 mA c. 50 V, 110 mA d. 50 V, 120 mA An R-C series circuit, initially at rest has a step voltage signal. The response v(t) across C is v(t) = 1 — e–3t. If now there is an initial voltage at C of 3 volts, what is v(t) for the same step signal? a. 1 + 3e–3t b. 1 + 2e–3t c. 3e–3t d. None of the above

95.

Norton equivalent to the network N to the left of AB is a cu rent source 1N = 4 A from B to A, RN = 2Ω. The current through R when it is connected across AB = 2A. What is the value of resistance R? a. 1Ω b. 2Ω c. 3Ω d. 4Ω In a series R-L-C circuit, the maximum voltage across the capacitor occurs at a frequency a. double the resonant frequency b. equal to resonant frequency 2 times the resonant frequency c. d. below the resonant frequency

96.

92.

In the circuit shown in the above figure, e1(t) = 3 cos(ωt + 30°) and e2(t) =

In the circuit shown above, what is the voltage across 5 Ω resistor ? a. —30V b. 30V c. 1250 V d. —1250 V

97.

Consider the following network functions : ( s 2 + 1)( s 2 + 4 ) 1. ( s 2 + 3)( s 2 + 9 ) 2.

3.

(s

2

101.

+ 1)( s 2 + 9 )

12 of 15 d. Only l and 3 2( s 2 + 1)( s 2 + 9) Z (s) = may be s ( s 2 + 4) synthesized into Cauer first form as

s ( s2 + 4)

s ( s2 + 9)

( s + 1)( s s ( s + 4) ( s + 1) 2

2

+ 4)

a.

2

4.

98.

99.

100.

2

Which of the above functions can represent L-C driving-point immittances ? a. Only 1 and 2 b. Only 2 and c. Only 2 and 4 d. Only 1 and 3 A series R-L-C circuit excited by a 100 V, variable frequency source, has a resistance of 10 Ω and an inductive reactance of 50Ω at 100 Hz. If the resonance frequency is 500 Hz, what is the voltage across the capacitor at resonance? a. 100 V b. 500V c. 2500V d. 5000 V What is the transfer function of a system whose impulse response is e–3t sin 2t? 13 a. 2 s + 6s + 13 1 b. 2 s + 6s + 13 2 c. 2 s + 6s + 13 5 d. 2 s + 6s + 13 Consider the following statements in connection with the properties of R-C impedance functions: 1. All the poles and zeros are simple. 2. Poles and zeros interlace. 3. Poles and zeros are located on the negative real axis of the s-plane. Which of the statements given above are correct? a. 1, 2 and 3 b. Only l and 2 c. Only 2 and 3

b.

c.

d. 102.

103.

If the driving-point impedance Z11 of the network shown in the figure above is given ⎛ s+3⎞ by Z11 = k1 ⎜ ⎟ then what is the ⎝ s +8⎠ driving-point impedance Z22 ? ⎛ s+5⎞ a. k2 ⎜ ⎟ ⎝ s+3⎠ ⎛ s+5⎞ b. k2 ⎜ ⎟ ⎝ s +8⎠ ⎛ s+3⎞ c. k2 ⎜ ⎟ ⎝ s+5⎠ ⎛ s +8⎞ d. k2 ⎜ ⎟ ⎝ s+5⎠ (k1 and k2 are scale factors) What is the series resistance required to extend the 0-100 V range of a 20000 Ω/V meter to 0-1000 V?

104.

105.

106.

107.

108.

109.

a. 10 MΩ b. l6 MΩ c. 18 MΩ d. 20 MΩ The voltage coil of a single-phase house service energy meter a. is highly resistive b. is highly inductive c. is highly capacitive d. has a phase angle equal to load power factor angle Which of the following can be used/modified for measurement of angular speed? 1. LVDT 2. Magnetic pick-up 3. Tacho-generator 4. Strain gauge Select the correct answer using the code given below: a. Only 1 and 2 b. Only 2 and 3 c. Only 3 d. Only 2, 3 and 4 Piezo-electric crystal is generally employed for the measurement of which one of the following? a. Flow b. Velocity c. Acceleration d. Temperature In microwave telemetry, repeater stations are required at every a. 2 km b. 5 km c. 40 km d. 100 km Data acquisition systems are usually of a. analog type b. digital type c. integrating type d. hybrid type A successive approximation A/D converter has a resolution of 20 mV. What is its digital output for an analog input of 2.17 V? a. 01101100 b. 01101101 c. 0110101 d. 01110100

110.

111.

112.

13 of 15 A doctor is using a digital clinical thermometer, which employs an A/D converter. The converter provides for both ±ve and —ve reference inputs in place of only +ve and ground potential reference inputs. V +ref = 2.16 V and V −ref = 1.85 V. The amplifier used for the converter input generates signal of 20 mV per °F of body temperature. The converter output is between 00000 and 11111. Which one of the following is correct? a. The thermometer range is 9.25 °F to 108 °F b. The thermometer range is 46 °F to 216 °F c. The thermometer range is 0°F to 108 °F d. The thermometer cannot be used to measure body temperature 98.4°F Which one of the following bridges can be used to construct a harmonic distortion analyzer? 1. Maxwell bridge 2. Hay bridge 3. Schering bridge 4. Wien bridge Select the correct answer using the code given below : a. Only 1 and 2 b. Only 2 and 3 c. Only 3 and 4 d. Only 4 One cycle of a square wave signal observed on an oscilloscope is found to occupy 6 cm at a scale setting of 30μs/cm. What is the signal frequency? a. 1.8 kHz b. 5.55 kHz c. 18 kHz d. 55.5 kHz

113.

The signal flow graph shown above has M number of forward paths and P number of individual loops. What are their values? a. M = 4 and P = 2 b. M = 6 and P = 3 c. M = 4 and P = 3

14 of 15 114.

d. M = 6 and P = 2 Match List-I (Polar Plot of System) with List-Il (System Type) and select the correct answer using the code given below the Lists : List I

A. Rise time B. Peak time C. Peak overshoot. D. Settling time. List -II (Expression) ⎛ 1− δ 2 π − tan −1 ⎜ ⎜ δ ⎝ 1. ωn 1 − δ 2

A.

2.

⎞ ⎟ ⎟ ⎠

π ωn 1 − δ 2

( −πδ / 1−δ ) 2

3. e

B.

C. List-II 1. Type 0 2. Type 1 3. Type 2 A a. 1 2 b. c. 3 1 d.

4.

117.

B 3 1 2 2

C 2 3 1 3

115.

118.

116.

What is the approximate value of the gain margin in the Nyquist diagram given above? a. 0.67 b. 3.0 c. 1.0 d. 1/3 A second-order control system has a transfer function ωn2 C ( s) = 2 R( s) s + 2δωn s − ωn2 For unit step input, match List - I with List- II and select the correct answer using the code given below the Lists List- I (Time Domain Specification)

4

δωn

A B C D 1 2 3 4 a. b. 3 4 1 2 1 4 3 2 c. 3 2 1 4 d. Consider the following statements in connection with the addition of a pole to the forward path transfer function : 1. Closed-loop system becomes less stable. 2. Rise time of the system increases. 3. Bandwidth of the system increases. Which of the statements given above are correct? a. Only 1 and 2 b. Only 2 and 3 c. Only 1 and 3 d. 1, 2 and 3 The open-loop transfer function for unity feedback system is given by 5(1 + 0.1s ) s (1 + 5s )(1 + 20 s ) Consider the following statements 1. The steady-state error for a step input of magnitude 10 is equal to zero. 2. The steady-state error for a ramp input of magnitude 10 is 2. 3. The steady-state error for an acceleration input of magnitude 10 is infinite. Which of the statements given above are correct? a. Only 1 and 2 b. Only 1 and 3 c. Only 2 and 3

15 of 15 119.

d. 1, 2 and 3 Match List-I (Nyquist Plot) with List-Il (Frequency Response) and select the correct answer using the code given below: List I 3.

A. 4. B.

120.

A 4 a. 4 b. c. 2 2 d. The Nyquist below :

B 3 2 1 4 plot of

C D 2 1 1 3 3 4 3 1 a system is sketched

C.

D.

List-II

Corresponding to this plot, what is the open-loop transfer function? k a. (1 + sT1 )(1 + sT2 )(1 + sT3 ) b.

k s (1 + sT1 )(1 + sT2 )(1 + sT3 )

c.

k s (1 + sT1 )(1 + sT2 )

d.

k s (1 + sT1 )(1 + sT2 )(1 + sT3 )

1.

2.

2

2

1 of 13

I.E.S- (OBJ) 2008

ELECTRICAL ENGINEERING PAPER-I 1.

2.

3.

4.

Consider the following statements: When all the elements in one row of the Routh’s tabulation are zero then this condition indicates 1. one pair of real roots with opposite sign in s-plane 2. one pair of conjugate roots on the imaginary axis in s-plane 3. conjugate roots forming a quadrate in s-plane Which of the statements given above is/are correct? a. 1 only b. 2 only c. 3 only d. l, 2 and 3 The low frequency and high frequency asymptotes of Bode magnitude plot are respectively -60 db/decade and -40 db/dccade. What is the type of the system? a. Type 0 b. Type I c. Type II d. Type III Which one of the following is correct? If the open-loop transfer function has one pole in the right half of s-plane, the closed loop system will be stable if the Nyquist plot of GH a. does not encircle the (-1 + j0) point b. encircles the (-1 + j0) point once iii the counter-clockwise direction c. encircles the (-1 + j0) point once in the clockwise direction d. encircles the origin once- in the counter-clockwise direction Which one of the following is correct? The value of the system gain at any point on a root locus can be obtained as a a. product of lengths of vectors from the poles to that point

5.

6.

b. product of lengths of vectors from mm the zeroes to that point c. ratio of product of lengths of vectors from poles to that point to the product of length of vectors from zeros to that point d. product of lengths of vectors from all poles to zeros Which one of the following is correct ? The slope of the asymptotic Bode magnitude plot is integer multiple of a. ± 40 db/decade b. ± 12 db/decade c. ± 6 db/decade d. ± 3 db/decade What is the range of K for Which the open K loop transfer function G ( s ) = 2 s ( s + a)

represents an unstable closed loop system? a. K > 0 only b. K = 0 only c. K < 0 only 7.

8.

d. - ∞ < K < ∞ The characteristic polynomial of a discrete time system is given by z2 + z + a. For what value of ‘a’ is the system stable ? a. 2 b. 0.5 c. 1.5 d. -0.5 Isocline method is used for which one of the following? a. Design of nonlinear system b. Construction of root loci of nonlinear system c. Construction of phase trajectories of nonlinear systems d. Stability analysis of non-linear system

9.

10.

11.

12.

13.

To detect the position error in a position control system, which of the following may be used? 1. Potentiometers 2. Syncbros 3. LVDT Select the correct answer using the code given below: a. 1 and 2 only b. 1 and 3 only c. 2 and 3 only d. 1, 2and 3 Single step response of a typical stepper motor is quite oscillatory. Brakes are used to reduce or eliminate oscillations. Which one of the following statements is not correct regarding use of brakes? a. It provides memory or position information when motor is switched off. b. reduces deceleration time. c. It reduces length of motor load. d. It reduces pullout torque. Synchro machines are used for which one of the following? a. Converting 1-phase supply to 3-phase supply b. Stepping up low frequency signal to high frequency c. Detection of positional error in a.c. servo system d. Detection of positional error in d.c. servo system A, B, C and D represent the transmission parameters of a two-port network. When is the network reciprocal? a. AB - CD = 1 b. AD - BC = 1 c. AB - CD = 0 d. AD – BC = 0 Match List I with List II and select the correct answer using the code given below the lists; List-I (Network parameter) A. h11 B. h12

14.

2 of 13 C. h22 D. h21 List-II (Dimension) 1. Impedance 2. Admittance 3. Current ratio 4. Voltage ratio Code: A B C D 2 4 1 3 a. 2 3 1 4 b. 1 3 2 4 c. d. 1 4 2 3 Which one of the following is correct? The impedance function

(s z (s) =

15.

16.

17.

2

+ 1) ( s 2 + 3)

s ( s2 + 2)

is an

a. LC driving point function b. RL driving point function c. RC driving point function d. PLC driving point function Which one of the following passive components has the most precise and accurate standard ? a. Resistance b. Inductance c. Capacitance d. Conductance. Which of the following is/are primary standard(s) for voltage maintained by National Standards Laboratories? 1. Zener diode with 1.5 V output at 20°C 2. Nickel cadmium rechargeable cell of 1.25 V output at 20 °C Select the correct answer using the code given below: a. 1 only b. 2 only c. Both 1 and 2 d. Neither 1 nor 2 What is the prefix tera equivalent to? a. 103 b. 106

18.

c. 109 d. 1012 The errors introduced by an instrument fall in which category? a. Systematic errors b. Random errors c. Gross errors d. Environmental errors

24.

19.

25.

20.

21.

22.

23.

A waveform shown in the figure above, is fed to a d.c. ammeter. What is the reading shown by the meter ? a. Zero b. 50 rn-A c. 75mA d. 100 mA Which one of the following instruments is commonly used to measure primary current of a transformer connected to mains? a. Electrostatic meter b. Current transformer c. Moving coil type meter d. Moving iron meter What is clamp-on ammeter used for ? a. Low a.c. current b. High a.c. current c. Low d.c. current d. High d.c. current Which one of the following is used for the measurement of 3-phase power factor? a. Power factor meter b. Crosse coil power factor meter c. Phase-angle waft hour meter d. Polarised-vane power factor meter What is the ‘swamping’ resistance which is connected in series with the working coil of a voltmeter to drastically reduce the error in measurement caused due to variation in temperature, made of? a. Constantan

26.

3 of 13 b. Eureka c. Manganin d. Nichrome How can a milli-ammeter be used as a voltmeter ? a. By connecting a low resistance in parallel with the instrument b. By connecting a high resistance in parallel with the instrument c. By connecting a low resistance in series with the instrument d. By connecting a high resistance in series with the instrument The principle of Hall effect is made use of in the construction of which one of the following? a. Ammeter b. Voltmeter c. Gaussmeter d. Galvanometer What is the radiation resistance of a dipole antenna λ/20 long approximately equal to? a. 2 Ω b. 40 Ω c. 0.6 Ω

27.

28.

d. 20Ω According to maximum power transfer theorem, when is the maximum power absorbed by one network from another network? a. The impedance of one of the networks is half that of the other b. The impedance of one is the complex conjugate of the other c. The impedance of one is equal to that of the other d. Only the resistive parts of both are equal Consider the following statements for transmission lines: 1. When a transmission line is terminated by its characteristic impedance the line will not have any reflected wave. 2. For a finite line terminated by its characteristic impedance the velocity and current at all points on the line are exactly same.

29.

30.

31.

32.

3. For a lossless half wave transmission line the input impedance is not equal to load impedance. Which of the statements given above are correct? a. 1 and 2 only b. 2 and 3 only c. 1 and 3 only d. 1, 2 and 3 Which of the following is a vector quantity? a. Standing wave ratio only b. Reflection coefficient only c. Gain d. Standing wave ratio and reflection coefficient What causes electromagnetic wave polarization? a. Refraction b. Reflection c. Longitudinal nature of electromagnetic wave d. Transverse nature of electromagnetic wave A plane wave traveling in air is incident on a conducting medium. Which one of the following is correct? The magnetic field intensity a. becomes approximately half b. gets approximately doubled c. remains unchanged d. cannot be determined Consider the following three equations: r r ∂B 1. ∇ × E = − ∂t r r r ∂D 2. ∇ × H = J + ∂t r 3. ∇ . B = 0

Which of the above appear in Maxwell’s equations? a. 1, 2 and 3 b. 1 and 3 only c. 2 and 3 only d. 1 and 3 only

33.

34.

35.

36.

4 of 13 Which one of the following modes has the highest cut off wavelength in a rectangular wave guide? a. TE10 b. TE01 c. TM01 d. TM11 A long straight wire carries a current I = 10 A. At what distance is the magnetic field H = 1 AM-1? a. 1.19 m b. 1.39 m c. 1.59 m d. 1.79 m r The magnetic vector potential A obeys which equations? r r 1. B = ∇ × A r r 2. ∇ 2 A = − μ 0 J r r μ 0 IDI 3. A = ∫ 4πR Select the correct answer using the code given below: a. 1 and 2 only b. 2 and 3 only c. 1 and 3 only d. 1, 2 and 3 The force on a charge moving with velocity v under the influence of electric and magnetic fields is given by which one of the following? r r r a. q E + B × v r r r b. q E + v × H r r r c. q H + v × E r r r d. q E + v × B

( ( ( (

37.

38.

)

) ) )

Which one of the following is the correct statement? Equi-potential lines and field lines a. are parallel b. are anti-parallel c. are orthogonal d. bear no definite relationship Consider the following statements for an electrostatic field:

39.

1. Its curl is zero 2. It is negative of gradient of scalar potential φ 3. It is conservative Which of the statements given below are correct? a. 1 and 2 only b. 2 and 3 only c. 1 and 3 only d. 1, 2 and 3 The input-output relationship of a system is given by d 2 c(t ) dc(t ) +3 + 2c(t ) 2 dt dt where r(t) and c(t) are input and output respectively. The transfer function of the system is equal to 1 a. 2 s +s+2

42.

43.

r (t ) =

(

40.

)

b.

1 s + 3s + 2

(

)

c.

2 s + 3s + 2

(

)

d.

1 s + 5s + 3

(

2

2

45.

Consider the function:

F (s) =

41.

)

2

44.

ω s +ω2 2

where F(s) = Laplace transform of f(t). The final value of f(t) is equal to a. infinite b. zero c. finite constant d. a value in between —1 and +1 Given the Laplace transform of f(t) = F(s) the Laplace transform of [f(t)e-at] is equal to: a. F(s + a) F ( s) b. (s + a c. easF(s) d. e-asF(s)

46.

47.

5 of 13 The impulse response of a secondorder under-damped system starting from rest is given by

c(t) = 125. e-6t sin 8t, t ≥ 0. The natural frequency and the damping factor of the system are respectively a. 10 and 0.6 b. 10 and 0.8 c. 8 and 0.6 d. 8 and 0.8 Given a unity feedback system with K G(s) = the value of K for damping s( s + 4) ratio of 0.5 is: a. 1 b. 4 c. 16 d. 64 For type 2 system, the steady-state error due to ramp input is equal to: a. zero b. finite constant c. infinite d. indeterminate The type number of the control system with K ( s + 2) G(s) H (s) = is s ( s 2 + 2 s + 3) a. one b. two c. three d. four A discrete-time system is stable if all the poles of the Z-transfer function of the system lie a. outside the circle of unit radius on the Z-plane b. within a circle of unit radius on the Zplane c. to the left of imaginary axis on the Zplane d. to the right of imaginary axis on the Zplane The Nyquist plot of a system passes through (-1, j0) point in the G(jω) H(jω) plane, the phase-margin of the system is:

48.

49.

50.

a. infinite b. greater than zero but not infinite c. zero d. less than zero If the poles of a system lie on the imaginary axis, the system will be: a. Stable b. Conditionally stable c. Marginally stable d. Unstable The transfer function of a P-I controller is a. Kp+Ki.s b. Kp + (K/s) c. (Kp/s) + K.s d. Kp.s + (Ki/s) Given the matrix ⎡0 1 0⎤ A = ⎢⎢ 0 0 1 ⎥⎥ ⎢⎣− 6 − 11 − 6⎥⎦

51.

52.

the eigenvalues of A are a. -1, -2, -3 b. -1, 2, -3 c. 0, 0, -6 d. -6, -11, -6 The state-variable description of a linear autonomous System is X& = AX where X is a two-dimensional state vector and A is ⎡0 2⎤ a matrix given by A = ⎢ ⎥ ⎣2 0⎦

53.

54.

55.

56.

The poles of the system are located at: a. -2 and +2 b. -2j and +2j c. -2 and -2 d. +2 and +2 The information contained in a signal is preserved in the sampled version if a. ω s = ω m b. ω s = 0.5ω m

c. ω s = 0.1ω m d. ω s = 2ω m

57.

6 of 13 (Where ω s is the sampling frequency and ω s is the maximum frequency contained in the signal.) For a tachometer if θ (t ) is the rotor displacement, e(t ) is the output voltage and Kt it the tachometer constant, then the transfer function is defined as a. Kt.s2 b. Kt.s c. Kt/s d. Kt A tachometer is added to a servomechanism because a. It is easily adjustable b. It can adjust damping c. It converts velocity of the shaft to a proportional d.c. voltage d. It reduces steady-state error Assertion (A): Ferrites are useful at very high frequencies. Reason (R): Ferrites have high permeability and high resistivity. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): A percisison instrument is always accurate. Reason (R): A precision instrument is one where the degree of reproducibility of the measurements is very good. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): A PMMC instrument is used for reading both d.c. and a.c. signals. Reason (R): The deflecting torque in a PMMC instrument is directly proportional to the current in the moving coil. a. Both A and R are individually true and R is the correct explanation of A

58.

59.

60.

61.

62.

b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Piezoelectric transducers can be used for measurement of both static and dynamic phenomena. Reason (R): Piezoelectric transducers have very good high frequency response. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Sampled-data system requires hold circuit. Reason (R): Hold circuit converts the signal to analog form. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Capacitive transducers can be used for measurement of both static and dynamic phenomena. Reason (R): capacitive transducers are extremely sensitive. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Two coils are coupled in such a way that the mutual inductance between them is 16 mH. If the inductances of the coils are 20 mH and 80 mH respectively, the coefficient of coupling is: a. 0.01 b. 0.4 c. 0.1 d. 0.0025 For a transmission line load matching over a range of frequencies, it is best to use a

63.

7 of 13 a. Balun transformer b. Single stub of adjustable position c. Double stub d. Broad band directional coupler The capacitance of an insulated conducting sphere of radius R in vacuum is: a. 2πε 0 R b. 4πε 0 R c. 4πε 0 R 2 d. 4πε 0 / R

64.

65.

66.

67.

Two materials having temperature coefficient of 0.004 and 0.004 respectively are joined in series. The overall temperature coefficient is approximately: a. 0.08 b. 0.04 c. 0.001 d. 0.0001 A 10 μF capacitor is fed from an a.c. voltage source containing a fundamental and a third harmonic of strength one-third of fundamental. The third harmonic current flowing through the capacitor expressed as percentage of the fundamental under steady-state condition will be: a. 150% b. 100% c. 50% d. 33% In a two element series network, the voltage and current respectively are given as, v(t) = 50 sin (314 t) + 50 sin (942 t) V i(t) = 10 sin (314 t+ 60°) + 8 sin (942t + 45°) A, then the power factor of the network is approximately: a. 0.9 b. 0.6 c. 0.3 d. 0.1 (s + 2 ) The network function, F ( s) = (s + 1)(s + 3) represents an: a. RL impedance only b. RC impedance only c. RL admittance and RC impedance

8 of 13 68.

69.

70.

71.

d. RC admittance and RL impedance In a CRO astigmatism is: a. A source of generating fast electrons b. A medium for absorbing secondary emission electrons c. An additional focus control d. A time-delay control in the vertical deflection system In an electrometer, the movable plate is 11 cm in diameter. When 12 kV is applied between the movable plate and the fixed plate, the force is 0.006 N. The change in capacitance for 1.5 mm movement of the movable plate is: a. 0.44 × 10-12F b. 0.37 × 10-6F c. 0.125 × 10-12F d. 12.5 × 10-12F Continuous recording of a signal is not possible in a a. Magnetic tape recorder b. Strip chart recorder c. X Y recorder d. Galvanometric recorder The successive approximation A/D output for a 4-bit converter to a 8.217 Volt input (if the reference is 5 V) will be: a. 1101 b. 0110 c. 1010 d. 1001

72.

75.

What is the time constant of the circuit above? a. 0.5 s b. 1s c. 2s d. 4s 76.

In the circuit shown above, when is the power absorbed by the 1 Ω resistor maximum? a. R = 0 b. R = 2 Ω c. R = 4 Ω d. R = ∞ 73.

74.

For circuit shown above, the black box contains resistors and independent sources only. The current I is 3 A and 1.5 A for R = 0 and 2Ω, respectively. For R = 1Ω, what is the current I? a. 1A b. 2A c. 3A d. 4A What is the Laplace transform of a function δ (t-2) ? a. 2 b. 0 c. e-2s d. 2s

In the network shown above, it is given dv that v = 1 V and = -10 V/s at a time t, dt where t is the time after the switch S is closed. What is the value of C? a. 0.05 F b. 0.1 F c. 0.15 F d. 0.2 F

9 of 13 77.

A series R-L circuit is to be connected to an a.c. source v(t ) = Vm sin(ωt + ϕ ) volt. Which one of the following is correct? The transient current will be absent if the source is connected at a time t0 such that

b.

a. ω t0 = 0 b. ω t 0 =

π

c.

2

c. ω t0 = tan −1

ωL R

d. ω t 0 has any arbiter value 78.

A series R-L-C circuit is switched on to a step voltage V at t = 0. What are the initial and final values of the current in the circuit, respectively? a. V/R, V/R b. Zero, Infinity c. Zero, Zero d. Zero, V/R

d. 82.

For the network shown above, if the current i (t ) = 2 sin(ωt − 30°), then what is the value of R?

79.

a. 1Ω b. 3Ω c.

80.

What does the function f(t) plotted in the above figure represent? a. Unit step function b. Unit impulse function c. Unit ramp function d. Unit Parabolic function A lossy capacitor is represented by an ideal capacitor C with a high resistance R in parallel. What is the Q of the circuit at frequency ω?

d. 3 3 Ω 83.

84.

a. ωCR b. 1/(ωCR) c. ωC/R d. R/(ωC) 81.

A voltage of V = 100∠30° is applied to an impedance Z = 3 + j4. Which one of the following is the power triangle?

a.

3Ω

85.

A control system has a transfer function K (1 + 0.5s )(1 + 2s + 5s 2 ) . s 2 (1 + s )(1 + 5s + 10 s 2 )(1 + 100s + 500 s 2 ) What is the type of the system? a. 0 b. I c. II d. III Which one of the following is correct? Final value theorem is not applicable for the system when the input is: a. Step b. Ramp c. Parabolic d. Exponential Which one of the following statements regarding steady state errors in control system is not correct? a. Steady state error analysis relies on the use of initial value theorem.

10 of 13

86.

87.

88.

b. Steady state error is a measure of system accuracy when a specific type of input is applied to a control system. c. The error constants do not give information regarding steady state error when inputs are other than step, ramp and parabolic. d. Steady state error docs not provide information on how the error varies with time. Which one of the following is the most likely reason for large overshoot in a control system? a. High gain in a system b. Presence of dead time delay in a system c. High positive correcting torque d. High retarding torque In the time domain analysis of feedback control systems which one pair of the following is not correctly matched? a. Under damped:- Minimizes the effect of nonlinearities b. Dominant Poles:- Transients die out more rapidly c. Far away poles to the left half of splane:- Transients die out more rapidly d. A pole near to the left of dominant complex poles and near a zero:Magnitude of transient is small Which of the following transfer functions is/are minimum phase transfer function(s)? 1 1. ( s − 1) 2.

( s − 1) ( s + 3)( s + 4)

3.

( s + 2) ( s + 3)( s − 4)

Select the correct answer using the code given below: a. 1 and 3 b. 1 only c. 2 and 3 d. None 89.

90.

91.

92.

The transfer function for the diagram shown above is given by which one of the following? a. 1/(1+sRC) b. sRC/(1+sRC) c. sRC/(1-sRC) d. 1+sRC The instrumentation amplifiers are used principally to amplify signals from which of the following? a. Transducers b. Active fillers c. Choppers d. D/A converters Which of the following primary detector type transducers are employed for displacement measurement? 1. Thermistor 2. diaphragm 3. Thermocouple 4. Pivot Torque Select the correct answer using the code given below: a. 1 and 2 b. 2 and 4 c. 3 and 4 d. 1 and 4 Match List-I with List-II and select the correct answer using the code given below the lists: List-I A. Variable capacitance device B. Orifice meter C. Thermistors List-II 1. Flow Measurement 2. Temperature measurement 3. Pressure transducer 4. Force and torque measurement Code:

93.

94.

95.

96.

97.

98.

99.

a. A3, B1, C2 b. A2, B4, C3 c. A2, B1, C3 d. A3, B4, C2 Which displacement transducer is used for accurate and linear measurement? a. LVDT b. Strain gauge c. Potentiometer d. Capacitive displacement transducer Which amplifier is used in an electronic multimeter? a. Power amplifier b. Buffer amplifier c. Differential amplifier d. Wideband amplifier For low resistance (from few micro ohms to one ohm) measurement, which bridge is used? a. Wheatstone bridge b. Kelvin bridge c. Guarded Wheatstone bridge d. Maxwell bridge Which bridge is used to determine frequency? a. Anderson bridge b. De Sauty bridge c. Wien bridge d. Campbell bridge The dielectric loss of a capacitor can be measured by which one of the following? a. Wien bridge b. Owen bridge c. Schering bridge d. Maxwell bridge Inductance is measured by which one of the following? a. Wien bridge b. Schering bridge c. Maxwell bridge d. Owen bridge Schering bridge can be used to measure which one of the following? a. Q of a coil b. Inductance and its Q-value

100.

101.

102.

11 of 13 c. Very small resistance d. Capacitance and its power factor What is a differential transformer? a. Constant pressure transducer b. Variable pressure transducer c. Constant displacement transducer d. Variable inductance transducer The imperfect capacitance which is shunted by a resistance can be measured by which one of the following? a. Carey Foster bridge b. Owen bridge c. Schering bridge d. Wien bridge Due to which one of the following reasons bearings of PMMC Instrument are made of Jewel? a. To avoid wear and tear of the moving system b. To provide a small support c. It can be easily replaced d. To make the system robust

103.

For the circuit shown, what is the voltage V if the source voltage is reduced by 50%? a. IR + E b. E – IR c. 2IR – (E/2) d. (E/2) – IR 104.

Voltage source is represented as shown in the figure given above. What is the equivalent current source?

12 of 13 If the voltage V across 10 Ω resistance is 10 V, what is the voltage E of the voltage source in the circuit shown above? a. -50 V b. -10 V c. +10 V d. +50 V

a.

b. 108. c.

d. 105.

109.

For the network shown in the figure, what is the voltage across the current source I? a. V – RI b. V + RI c. Zero d. RI – V

110.

106.

What is the value of the current I in the circuit shown above? a. 20 A b. 25 A c. 30 A d. 36 A 107.

111.

In the circuit shown above, what is the value of the current I? a. 1A b. 2A c. 3A d. 4A Why is the core of the transformer built up of lamination? a. To reduce eddy current loss b. For convenience of fabrication c. No specific advantage d. For increasing the permeability Materials which lack permanent magnetic dipoles are known as: a. Paramagnetic b. Diamagnetic c. Ferromagnetic d. Ferrimagnetic Match List-I with List-II and select the correct answer using the code given below the lists: List-I (Material) A. Silicon steel B. Ferrites C. Alnico List-II (Application) 1. High frequency transformers 2. Permanent magnets 3. Current transformers 4. Power transformers Code:

112.

113.

114.

115.

116.

A B C a. 1 2 4 b. 4 3 2 3 4 1 c. d. 4 1 2 Which one of the following is the correct statement? The orientational polarizability in a polyatomic gas is proportional to a. temperature T b. 1/T c. T2 d. independent of T In the case of a dielectric subjected to an alternating electric field of frequency f, the dielectric loss is proportional to which one of the following? a. f b. f2 c. 1/f d. 1/f2 The electronic Polaris ability of an inert gas atom is proportional to which one of the following? a. R b. R2 c. R3 d. R4 (Where R is the radius of the atom) Fermi level in a p-type semiconductor lies close to which one of the following? a. The top of the valence band b. The bottom of the valence band c. The top of the conduction band d. The bottom of the conduction bond Consider the following statements about semiconductors? 1. The forbidden energy gap in semiconductors lies between the valence band and conduction band. 2. The forbidden energy gap in germanium at 0 K is about 0.72 eV. have negative 3. Semiconductors temperature coefficient of resistivity. Which of the statements given above are correct?

117.

118.

119.

120.

13 of 13 a. 1, 2 and 3 b. 1 and 2 only c. 2 and 3 only d. 1 and 3 only Which one of the following is the correct statement? When a p-n junction is reverse-biased, then a. Holes and electrons move away from the junction b. Depletion region decreases c. Barrier breaks down d. Minority carriers are not affected Consider the following statements about pn junctions: 1. p-n junction behaves as a capacitor when forward biased. 2. p-n junction has p and n type semiconductors with depletion layer in between. 3. p-n junction has a wider depletion layer as compared to a Zener diode. Which of the statements given above are correct? a. 1, 2 and 3 b. 1 and 2 only c. 2 and 3 only d. 1 and 3 only Which one of the following is the correct statement? The type of majority charge carriers in a semiconductor can be found by a. Hall effect b. Piezoelectric effect c. Photoelectric effect d. Meissner effect Which one of the following is the correct statement? During the process of magnetization of ferromagnetic material, the magnetic domains a. Only expand b. Rotate first and then expand c. Expand first and then rotate d. Neither rotate nor expand

I.E.S-(OBJ) 1997

1 of 16

ELECTRICAL ENGINEERING PAPER-II 1.

2.

3.

4.

5.

When a thyristor is negatively biased a. All the three junctions are negatively based b. Outer junctions are positively biased and the inner junction is negatively biased. c. Outer junctions are negatively biased and the inner junction is positively biased d. The junction near the anode is negatively biased and the one near the cathode is positively biased Consider the following semiconductor devices: 1. Triac 2. Thyristor 3. Amplifying gate thyristor. The correct sequence of these devices in increasing order of their di/dt capabilities is a. 1, 3, 2 b. 1, 2, 3 c. 3, 1, 2 d. 3, 2, 1 In dc choppers feeding highly inductive loads, the waveforms for input and output currents are a. Discontinuous and continuous respectively b. Both continuous c. Both discontinuous d. Continuous and discontinuous respectively A. single-phase voltage source squarewave inverter feeds pure inductive load. The waveform of the load current will be a. Sinusoidal b. Rectangular c. Trapezoidal d. Triangular In machine tool drive application, the speed of a separately excited dc motor is required to be controlled both below and

6.

7.

8.

above the rated speed of the motor. Which one of the following methods is best suited for this purpose? (Va = armature voltage, If = field current and If rated = field current at rated speed) a. If = If rated ‘Va variable b. Va fixed’ If variable c. Va and If variable, with If ≤ If rated d. Va and If variable, with If ≥ If rated A separately excited dc motor is required to be controlled from a 3-phase source for operation in the first quadrant only. The most preferred converter would be: a. Fully controlled converter b. Fully controlled converter with freewheeling diode c. Half-controlled converter d. Sequence control of two series connected fully controlled converters If the commutation angle of a diode rectifier (due to source inductance effect) is μ, then the inductive voltage regulation will be 1 + cos μ a. 2 cos μ b. 1 + 2 cos μ c. 1 − 2 1 − cos μ d. 2 Consider the following statements: The diodes in a voltage source inverter (McMurray inverter) should be able to 1. Withstand a large voltage in the reverse direction. 2. Carry the commutating current excess of load current. 3. Provide the required reverse bias to the outgoing thyristor. 4. Feedback the reactive current to the source.

9.

10.

Of these statements a. 1, 2 and 3 are correct b. 1, 3 and 4 are correct c. 2, 3 and 4 are correct d. 1, 2 and 4 are correct The ac-to-dc voltage ratio of a converter in the state of discontinuous conduction is a. Dependent upon the firing angle but independent of load time constant b. Dependent upon load time constant but independent of firing angle c. Dependent upon both firing angle and load time constant d. Independent of both firing angles and load time constant In a 3-phase bridge rectifier fed from the star connected secondary winding of a transformer, let the voltage to the neutral of the A - phase (phase sequence A, B, C) be Vm sin ω t. At the instant when the voltage of A-phase is maximum, the output voltage at the rectifier terminals will be

13.

14.

2 of 16 3. Suitable for low-power circuits. 4. Suitable for high-power circuits. Of these statements a. 1 and 2 are correct b. 1 and 3 are correct c. 2 and 3 are correct d. 2 and 4 are correct In dc choppers, per unit ripple is maximum when the duty cycle α is a. 0.2 b. 0.5 c. 0.7 d. 0.9 Match the 3 curves labelled A, B, C and D with the characteristics given under list-II and select the correct answer using the codes given below the figures:

a. Vm / 2 b. Vm c. 1.5 Vm d. 11.

12.

3Vm

Consider the following statements regarding speed control of induction motors by means of external rotor resistors: 1. Reduction in speed is accompanied by reduced efficiency 2. With a large resistance in the rotor circuit, the speed would vary considerably with variation in torque. 3. The method is very complicated. The Disadvantages of such a method of speed control would include a. 1 and 2 b. 2 and 3 c. 1 and 3 d. 1, 2 and 3 Consider the following statements: Switched mode power supplies are preferred over the continuous types, because they are 1. Suitable for use in both ac and dc. 2. More efficient.

15.

List II: Control characteristic of a 1. 3-pulse converter feeding pure resistance 2. Fully controlled converter feeding R-L load with perfect smoothing 3. Single-phase ac voltage controller feeding pure inductive load 4. 6-pulse half -controlled converted A B C D a. 1 2 3 4 b. 1 2 4 3 2 1 3 4 c. 2 1 4 3 d. A 3-pulse converter feeds a pure resistive load at a firing angle of α = 60°. The average value of current flowing in the load is 10 If a very large inductance is connected in the load circuit, then the a. Average value of current will remain as 10 A

16.

17.

18.

19.

b. Average value of current will become greater than 10A c. Average value of current will become less than 10 A d. Trend of variation of current cannot be predicted unless the exact value, of the inductance connected is known In a 3-phase rectifier circuit, thyristor number 1,2 and 3 are connected respectively to R, Y and B phases of the star- connected transformer secondary. When the current is being commutated from thyristor No. 1 to No. 2 the effect of the transformer leakage and the ac system inductance will be such that it will a. Prolong the conduction in No. 1 and delay the turn- on of No. 2 correspondingly b. Stop the conduction in No. 1 at the scheduled time, but delay the turn-on of No.2 c. Produce conduction in both No. 1 and No.2 in parallel for an overlapping period through a transient d. Double the voltage output through a commutation transient If an intrinsic semiconductor is doped with a very small amount of boron, then in the extrinsic semiconductor so formed, the number of electrons and holes will a. Decrease b. Increase and decrease respectively c. Increase. d. Decrease and increase respectively If α = 0.98, Ico = 6μA and Iβ = 100μA for a transistor, then the value of Ic will be a. 2.3 mA b. 3.1 mA c. 4.6 mA d. 5.2 mA The given figure shows a silicon transistor connected as a common emitter amplifier. The quiescent collector voltage of the circuit is approximately

a. 20/3 V

20.

21.

22.

23.

3 of 16 b. 10 V c. 14V d. 20V A difference amplifier is shown in the figure transistors Q1 and Q2 have identical parameters. Assuming that VBE = 0.7 V and β = 200 for each transistor and given that VSI = VSI = VS2 = 0, the value of the collector current IC will be

a. 2 mA b. 1 mA c. 0.5 mA d. 2.5 μA A junction transistor operating at room temperature with IC =2 mA where kT/q = 25 mV has β = 100. The values of the parameters gm in mhos and rπ in ohms will be respectively a. 0.04 and 2500 b. 0.08 and 1250 c. 0.5 and 800 d. 0.08 and 5000 An amplifier with mid-band gain |A| = 500 1 has negative feedback |β| = . If the 100 upper cut-off without feedback were at 60 kHz, then with feedback it would become a. 10 kHz b. 12 kHz c. 300 kHz d. 360 kHz The circuit shown in the figure has a Zener regulated dc power supply. Assuming that the Zener diode is ideal, the MINIMUM value of RL down to which the output voltage would remain constant is

a. 15 ohms b. 24 ohms c. 27 ohms

4 of 16 24.

⎡ R2 R4 ⎤ ⎢ R + R + R3 ⎥ 4 ⎥ c. − ⎢ 2 R ⎢ ⎥ 1 ⎢⎣ ⎥⎦

d. 45 ohms A non-inverting OP-AMP summer is shown in the figure. The output voltage V0 is

27.

25.

a. sin 100 t 3 b. sin100t 2 c. 2 sin 100 t d. 3 sin 100 t The expression for the output voltage V0 in terms of the input voltages V1 and V2 in the circuit shown in the figure, assuming the operational amplifier to be ideal is: V0 = AV 1 1 + A2V2 The values of A1 and A2 would be respectively

26.

a. 9 and -10 b. 9.9 and -10 c. -9 and 10 d. -9.9 and 10 The transfer gain for the circuit shown in the figure is given by

28.

29.

⎡ R + R3 ⎤ d. − ⎢ 2 ⎥ ⎣ R1 ⎦ Consider the following statements regarding an RC phase-shift oscillator: 1. The amplifier gain is positive. 2. The amplifier gain is negative. 3. The phase shift introduced by the feedback network is 180°. 4. The phase shift introduced by the feedback network is 360°. Of these statements a. 1 and 3 are correct b. 2 and 3 are correct c. 2 and 4 are correct d. 1 and 4 are correct If an input signal with non-zero dc component is applied to a low pass RC network, the dc component in the output will be a. The same as that in the input b. Less than in the input c. More than that in the input d. Zero For the given input, the output waveform across the diode shown in the figure will be

a.

R2 R3 ⎤ ⎡ ⎢ R2 + R3 + R ⎥ 4 ⎥ a. − ⎢ R ⎢ ⎥ 1 ⎢⎣ ⎥⎦ ⎡ R3 R4 ⎤ ⎢ R + R + R2 ⎥ 4 ⎥ b. − ⎢ 3 R1 ⎢ ⎥ ⎢⎣ ⎥⎦

b.

c.

5 of 16 d.

d. 30.

The waveform of the output of a low pass filter to a step input will bw as in a. 33. b.

c.

In a half-adder having two inputs A and B and two outputs (S and C are the Sum and Carry output bits respectively), the Boolean expressions for S and C in terms of A and B is: a. S = AB + A.B ; C = A.B b. S = AB + AB; C = A + B

c. S = A.B + AB; C = A + B d.

31.

32.

34.

The voltage levels for a negative logic system. a. Must necessarily be negative b. Could be negative or positive c. Must necessarily be positive d. Must necessarily be either zero or – 5V Which one of the following is the truth table of the given logic circuit?

a. b.

35.

a.

36. b.

c.

d. S = AB + A.B ; C = A + B A combinational circuit has inputs A, B and C and its Karnaugh Map is as shown. The output of the circuit is given by

( AB + AB ) C ( AB + AB ) C

c. ABC d. A ⊕ B ⊕ C The output Qn of a J-K flip-flop is zero. If changes to 1 when a clock pulse is applied. The inputs Jn and Kn are respectively a. 1 and X b. 0 and X c. X and 0 d. X and 1 To realize the given truth table from the circuit shown in the figure, the input to J in terms of A and would have to be

a. AB b. A

37.

38.

c. B d. AB The circuit schematic shown in the following figure

Represents 4-bits a. Static shift register b. Dynamic shift register c. Asynchronous counter d. Synchronous counter Match List-I (Function/circuit) with list-II circuit realization) and select the correct answer List I A. D-flip flop B. T-flip flop C. Exclusive OR D. Half adder List II 1.

40.

41.

2.

42. 3.

4.

39.

A B C D a. 2 3 1 4 b. 2 3 4 1 c. 3 2 4 1 3 2 1 4 d. The large the RAM of a computer, the faster is its speed. since it eliminates a. Need for ROM b. Need for external memory

43.

44.

6 of 16 c. Frequent disk I/Os s d. Need for a data-wind path DB. DW and DD directives are used to place data in particular locations or to simply allocate space without reassigning anything to space. The DW and DD directions are used to generate a. Offsets b. Full address of variables c. Full address of labels d. Offsets or full address of labels and variables Match List-I (Type of instruction) with list-II (Instruction) and select the correct answer List I A. One byte instruction B. Two bytes instruction C. Three bytes instruction D. Register indirect addressing List II 1. MOV A, data 2. MOV A, B 3. MOV A, M 4. JMP addr. A B C D a. 1 2 4 3 b. 2 1 4 3 c. 2 1 3 4 d. 1 2 3 4 Consider the following set of instructions: STC CMC MOV A,B RAL MOV B,A This set of instructions a. Doubles the number in Register be B b. Divides the number in Register by 2 c. Multiplies B by A d. Adds A and B The number bits needed to address 4K memory is a. 6 b. 8 c. 12 d. 16 The ESC instruction of 8086 may have two formats. In one of the formats, on

45.

46.

memory operand is used. Under this format, the number of external op-codes (for the co-processor) which can be specified is a. 64 b. 128 c. 256 d. 512 The TRAP is one of the interrupts available in TNTEL 8085. Which one of the following statements is true of TRAP? a. It is level triggered b. It is negative edge triggered c. It is positive edge triggered d. it is both positive edge triggered and level triggered Consider the following figures showing clock periods of Instruction Fetch machine cycle for INTEL 8085.

49.

The spectrum of the modulated signal will include which of the following frequency components? 1. f c + f1 + f 2

50.

51.

47.

48.

An ERROR in the above diagram relates to the signal a. IO/M b. SO c. SI d. R D In a 16-bit microprocessor, words are stored in two consecutive memory locations. The entire word can be read in one operation provided the first a. Word is even b. Word is odd c. Memory location is odd d. Memory address is even A 3×8 decoder with two enable inputs is to be used to address 8 blocks of memory. What will be the size of each memory block when addressed from a sixteen bit bus with two MSBs used to enable the decoder? a. 2 K b. 4 K c. 16 K d. 64 K

7 of 16 A carrier signal of frequency fc is modulated by a signal 2 A cos 2π f1t − A sin 2π f 2t

52.

53.

2.

f c − f1 − f 2

3.

f c + 2 f1 − f 2

4.

f c − 2 f1 + f 2

Select the correct answer using the codes given below: a. 1 and 2 b. 3 and 4 c. 3 alone d. 1, 2, 3 and 4 Which one of the following is the advantage of base modulation over collector modulation of a transistor Class C amplifier? a. Requires lower modulation power b. Higher power output per transistor c. Better efficiency d. Better linearity In a narrow band FM system. the highest modulating frequency is fm. The bandwidth of the system will be a. 6fm b. Fm c. 2fm d. 10fm A telephone channel will PCM gives good. performance at a transmission rat” of 64k bits/s. With companding and complex version pf delta modulation (DM), to achieve the same performance, the transmission rate must be close to a. 64 k bits/s b. 100 k bits/s c. 64 M bits/s d. 100 M bits/s Equalizing pulses in IV are placed during the a. Vertical blanking period b. Horizontal blanking period c. Serrations d. Horizontal retrace

54.

55.

56.

57.

58.

The most useful approach to radar system for monitoring the speed of moving vehicles is: a. Pulsed radar b. Monopulse c. Dopier radar d. Auto-tracking radar Consider the following statements: The maximum range of radar can be increased by 1. Increasing the peak transmitted power 2. Increasing the gain of the receiver 3. Increasing the diameter of the antenna 4. Reducing the wavelength used Of these statements a. 1,3 and 4 are correct b. 1,2,3 and 4 are correct c. 2 and 4 are correct d. 1 and 3 are correct Consider the following statements about broadband communications using submarine cables: 1. A submarine cable repeater contains filters for the two directions of transmission. 2. Armoured submarine cable is used for the shallow- shore ends of the cable. V 3. Fibre-optic submarine cable is used to prevent inadvertent plugging- in of the cable. Of these statements a. 1 and 2 are correct b. 2 and 3 are correct c. 1 and 3 are correct d. 1, 2, and 3 are correct To couple a coaxial line to a parallel wire line, it is best to use a a. Slotted line b. Balun c. Directional coupler d. Quarter-wave transformer Assertion A: A differentially compounded dc motor has the possibility of starting in the reversed direction. Reason R: Owing to higher inductance in the series field, the resultant main flux reverses during starting. a. Both A and Rare true and R is the correct explanation of A.

59.

60.

61.

62.

8 of 16 b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: In a salient-pole synchronous motor, the angular displacement of rotor per unit change of power is less than that for a similar cylindrical rotor machine. Reason R: A reluctance torque is developed in the salient- pole machine due to the effect of direct axis flux on the damper winding. a. Both A and Rare true and R is the correct explanation of A. b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: During the load flow study, a voltage controlled bus is treated as a load bus when the magnitude of the voltage is very much higher or very much lower than the scheduled voltage. Reason R: A tap changing transformer is represented as an net work in the load flow model. a. Both A and Rare true and R is the correct explanation of A. b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: In the residual type earth compensation used in the distance protection schemes with solidly earthed neutral systems, the residual compensation circuit uses auxiliary current transformers. Reason R: A fraction of the residual current is added to the fault current Ia for an earth fault on phase ‘a’. This fraction is so chosen that the relay measures the positive sequence impedance Z1. a. Both A and Rare true and R is the correct explanation of A. b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: In HVDC systems, the dc voltage should be as high as possible and

63.

64.

65.

66.

the rectifier control angle alpha should be as low as possible. Reason R: Control of dc voltage is exercised by the rectifier and inverter control angles alpha and gamma respectively. a. Both A and Rare true and R is the correct explanation of A. b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: A-3 phase induction motor operation on a 3-phase voltage controller for speed control cannot be used for constant torque loads. Reason R: The output voltage waveform of the controller is distorted, a. Both A and Rare true and R is the correct explanation of A. b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: TTL and CMOS cannot be normally used together. Reason R: TTL operates on a (+ 5 ± 0.25) V regulated supply voltage and some mA, while the CMOS operates on unregulated supply voltage of +3V to +15V and someμA. a. Both A and Rare true and R is the correct explanation of A. b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: Machine language program is written in hexadecimal. Reason R: Microprocessor can under stand hexadecimal number system. a. Both A and Rare true and R is the correct explanation of A. b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: The degree of modulation of radio- frequency voltage present at the input terminals of the diode is less than the

67.

68.

69.

9 of 16 degree of modulation of the original radio frequency signal in AM detector. Reason R It depends primarily on the ratio of the source impedance of the radio frequency voltage to the diode load impedance. a. Both A and Rare true and R is the correct explanation of A. b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion A: The different components of a composite video signal are needed consecutively and not simultaneously at the TV receivers. Reason R: The different components of the composite video signal are sent to the receiver on a frequency division basis. a. Both A and Rare true and R is the correct explanation of A. b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true If the applied voltage of a certain transformer is increased by 50% and the frequency is reduced to 50% (assuming) that the magnetic circuit remains unsaturated), the maximum core /flux density will a. Change to three, times the original value b. Change to 1.5 times the original value c. Change to 0.5 times the original value d. Remain the same as the original value The low-voltage winding of a core-type transformer is subdivided into two equal halves, each of half the original width of the single winding with the high-voltage winding in between these two halves of low-voltage winding (instead of having usual construction of low-voltage winding adjacent to the core and surrounded b the high-voltage winding.) Such an interlacing of coils would make the combined primary and secondary leakage reactance (in terms of the primary) nearly a. Twice b. Equal c. Half d. One-fourth

70.

71.

72.

73.

74.

Two 3-limb, 3-phase delta-star connected transformers are supplied from’ the same source. One of the transformers is of Dy 1 and the other is of Dy 11 connection. The phase difference between the corresponding phase voltages of the two second Aries would be a. 0° b. 30° c. 60° d. 120° In a transformer fed from a fundamental frequency voltage source, the source of harmonics is the a. Overload b. Poor insulation c. Iron loss d. Saturation of core A 40k VA transformer has a core loss of 400W and. a full-load copper loss of 800 W. The proportion of full-load at maximum efficiency is a. 50% b. 62.3% c. 70.7% d. 100% A single-phase transformer has a. rating of 15 k VA, 600/120V. It is reconnected as an auto- transformer to supply at 720 V from a 600 V primary source. The maximum load it can supply is a. 90 kVA b. 18 kVA c. 15 kVA d. 12 kVA The general expression for the instantaneous value of the torque of dynamo-electric machines is given by dM 1 1 2 dL1 2 dL2 T = ( i1 ) + ( i2 ) + i1i2 dθ 2 dθ dθ 2 Where i1 and i2 are rotor and stator currents respectively, L1 and L2 are rotor windings’ self inductances. M is the mutual inductance between stator and rotor windings and θ is the angular displacement of the rotor. For a synchronous machine (cylindrical rotor), the torque is given by only the third term of the equation, because a. The average value of (i1)2 and (i2)2 each is zero

10 of 16 b. The first and the second terms cancel each other dL1 dL2 and have opposite signs and c. dθ dθ dL1 dθ 2 i2 ) ( dL2 = 2 dθ ( i1 )

75.

76.

77.

d. L1 and L2 do not very with respect to θ Match List-I (Parts of electrical machines) with List - II (The approximate nature of the air-gap mmf pattern produced by them) and select the correct answer List I A. DC machine, stator B. DC machine, rotor C. Salient-pole synchronous machine, stator D. Squirrel-cage rotor of induction motor List II 1. Sinusoidal 2. Trapezoidal 3. Triangular A B C D a. 1 2 1 3 3 1 3 1 b. c. 2 3 1 3 d. 2 3 1 1 A dc shunt generator, when driven at its rated speed, is found to be not generating any voltage. Which of the following would account for this? 1. There is no residual magnetism. 2. The connection of the field winding is not proper with respect to the armature terminals. 3. The resistance of the field circuit is greater than the critical field resistance. 4. The load resistance is less than the critical armature resistance. Select the correct answer using the codes given below: a. 3 and 4 b. 1, 2 and 4 c. 1, 2 and 3 d. 1, 2, 3 and 4 To have spark less commutation, the armature reaction effect in a dc machine is neutralized by

11 of 16

78.

79.

a. Using compensating winding and commutating poles b. Shifting the brush axis from the geometrical neutral axis to the magnetic neutral axis c. Fixing the brush axis in line with the pole axis d. Increasing the field excitation In a dc shunt generator working on load, the brushes are moved forward in the direction of rotation. As a result of this, commutation will a. Improve but terminal voltage will fall b. Worsen and terminal voltage will fall c. Improve and terminal voltage will rise d. Worsen and terminal voltage will rise Match List-I (Ways of compounding series and shunt field windings of a dc compound generator) with list-II (Volt- ampere characteristics at constant speed) and select the correct answer using the codes given below the Lists: List I A. Over compounded B. Level compounded C. Differentially compounded D. Under-compounded List II 1.

80.

A B C D 3 1 4 2 a. 3 1 2 4 b. c. 1 3 2 4 d. 1 3 4 2 Which one of the following figures best represents the variation in armature current and speed with time during the stating of a dc shunt motor? a.

b.

c.

d. 2.

81. 3.

4.

A dc over compounded generator was operating satisfactorily and supplying power to an infinite bus when the prime mover failed to supply any mechanical power. The machine would then run as a a. Cumulatively compounded motor with speed reversed b. Cumulatively compounded motor with direction of rotation as before c. Differentially compounded motor with speed reversed d. Differentially compounded motor with direction of speed as before

82.

A 3-phase alternator with high rotational inertia and negligible armature resistance was delivering power to an isolated load when the armature terminals got shortcircuited. After a while, the mechanical power input to the shaft of the machine is terminated at time t0. The short-circuit current Is circulating in the armature will very till the machine comes to rest at time ts. Which one of the curves shown in the following figures best reflects this variation? a.

85.

b.

c.

86.

d.

83.

84.

When a synchronous motor is running at synchronous speed, the damper winding produces a. Damping torque b. Eddy current torque c. Torques aiding the developed to torque d. No torque For a given developed power, a synchronous motor operating from a constant voltage and constant frequency supply, will draw the minimum and maximum armature currents, Imin and Imax respectively, corresponding to a. Imm at unity pf, but Imax at zero pf b. Imax at unity pf, but Imin at zero pf c. Both Imin and Imax at unity pf d. Both Imin and Imax at zero pf

87.

12 of 16 Match list-I (Type of winding) with list-Il (Feature) and select the correct answer using the codes given below the Lists: List I A. Fractional slot windings B. Chorded and distributed windings C. Damper windings D. Single-phase windings List II 1. Only two- third of the pole pitch is occupied by the winding 2. Effects of slot harmonics are reduced or even eliminated 3. The effects of phase belt harmonics are reduced 4. Additional asynchro nous torque capability in projected pole motors A B C D 2 3 4 1 a. b. 2 3 1 4 c. 3 2 1 4 3 2 4 1 d. While conducting a “slip’ test for the determination of direct and quadratureaxis synchronous reactance’s Xd and Xq of a salient pole synhronous machine, the rotor of the machine is run with a slip’s’ and stator supply frequency ‘f’. The frequency of 1. Voltage induced across open field terminals. 2. Envelope of the armature terminal voltage, 3. Envelope of the armature current and 4. Armature current will be respectively a. sf, sf, sf and f b. sf, f, sf and f c. f, sf, f and sf d. f, (1– s) f, (2 – s) f and sf If two induction motors A and B are identical except that the air-gap of motor ‘A’ is 50% greater than that of motor ‘B’ then a. The no-load power factor of A will be better than that of B b. The no-load power factor of A will be poorer than that of B c. The core losses of A will be more than those of B d. The operating flux of A will be smaller than that of B

13 of 16 88.

89.

90.

91.

A 6-pole, 50Hz, 3-phase synchronous motor and an 8-pole, 50 Hz, 3-phase slipring induction motor are mechanically coupled and operate on the same 3-phase, 50 Hz supply system. If they are left opencircuited, then the frequency of the voltage produced across any two slip rings would be a. 12.5 Hz b. 25.0 Hz c. 37.5 Hz d. 50.0 Hz Which of the following statements regarding skewing of motor bars in a squirrel-cage induction motor are correct? 1. It prevents cogging. 2. It produces more uniform torque. 3. It increases starting torque. 4. It reduces motor ‘hum’ during its operations Select the correct answer using the codes given below: a. 2,3 and 4 b. 1,2, and 3 c. 1, 2 and 4 d. 1, 3 and 4 The rotor power output of a 3-phase induction motor is 15k Wand the corresponding slip is 4%. The rotor copper loss will be a. 600 W b. 625 W c. 650W d. 700 W For a more accurate analysis of the torque slip relation- ship, the equivalent circuit of a 3-phase induction motor for running condition is to be derived from the given stand-still condition:

92.

93.

94.

K1 = ratio of transformation E1 = V1 (applied voltage) - Iμs X1 Iμ = magnetizing current At running condition, if the two resistances in the equivalent circuit are denoted by A and B, then

The values of A and B will be a. K2 R1 and R2 b. SK2R1 and R2 c. K2 R1 and SR2 d. SK2R1 and SR2 A 3-phase wound rotor induction motor, when stated with load connected to its shaft, was found to start but settee down at about half synchronous speed. If the rotor winding as well as the stator winding were star connected, then the cause of the malfunctioning could be attributed to a. One of the stator phase windings being short-circuited b. One of the supply fuses being blown c. One of the rotor phases being opencircuited d. Two of the rotor phases being opencircuited Consider the following statements regarding fractional horse power shadedpole motor: 1. Its direction of rotation is from unshaded to shaded portion of the poles. 2. Its direction of rotation is from shaded to unshaded portion of the poles. 3. It can remain stalled for short periods without any harm. 4. It has a very poor power factor. Of these statements a. 1, 3 and 4 are correct b. 2, 3 and 4 are correct c. 2 and 4 are correct d. 1 and 3 are correct In the case of a converter- inverter speed control arrangement for an induction v motor operating with constant and with f negligible stator impedance a. The maximum torque is independent of frequency b. The maximum torque is proportional to frequency

95.

c. The slip at maximum torque is proportional to frequency d. The starting torque is proportional to frequency The load curve of a system is shown in the figure. The load factor of the system is:

100.

101.

96.

97.

98.

a. 1.66% b. 6.013% c. 16.6% d. 60.13% If the discharge is I m3/s and the head of water is 1, then the power generated by the alternator in one hour (assume 100% efficiency of the generator and turbine) will be a. 10 kW b. 73/75 k W c. 746/75 k W d. 100 kW Control rods used in nuclear reactors are made of a. Zirconium b. Boron c. Beryllium d. Lead Consider two parallel short transmission lines of impedances ZA and ZB respectively as shown in. the figure. Currents IA and IB are both lagging and the sending-end voltage is Vs. If the reactance to resistance ratio of both the impedances ZA and ZB are equal then the total current ‘I’ will

14 of 16 c. Obtain redial electric stress d. Obtain longitudinal electric stress Galloping in transmission line conductors arises generally due to a. Asymmetrical layers of ice formation b. Vortex phenomenon in light winds c. Heavy weight of the line conductors d. Adoption of horizontal conductor configurations In matrix form, the equation of a 4terminal network representing a transmission line a given by ⎡Vs ⎤ ⎡ A B ⎤ ⎡VR ⎤ ⎢ I ⎥ ⎢C D ⎥ ⎢ I ⎥ ⎦⎣ R⎦ ⎣ s⎦⎣ The two networks considered are A.

B.

The plausible transfer matrix for the networks (A) and (B) could be: i.

ii.

iii. ⎡1 ⎢Y ⎣

⎤ (1 + YZ )⎥⎦ Z

iv.

99.

a. Lag both IA and IB b. Lead both IA and IB c. Lag one of IA and IB but lead the other d. Be in phase with both IA and IB In a 3-core extra high voltage cable, a metallic screen around each coreinsulation is provided to a. Facilitate heat dissipation b. Give mechanical strength

102.

⎡1 + YZ Z ⎤ ⎢ Y 1 ⎥⎦ ⎣ The correct combination for the two networks (A) and (B), would be: a. (i) and (ii) b. (i) and (iii) c. (ii) and (iv) d. (iii) and (iv) The incremental generating costs of two generating units are given by IC1 = 0.1 X +20 Rs./MWhr.

103.

104.

105.

IC2= 0.15 Y+20Rs./MWhr. Where X and Y are power (in MW) generated by the two units. For a total demand of 300 MW, the values (in MW) of X and Y will be respectively a. 172 and 128 b. 128 and. 172 c. 175 and 125 d. 200 and 100 Consider the following statements: To provide reliable protection for a distribution transformer against over voltages using lighting arrestors, it is essential that the 1. Lead resistance is high. 2. Distance between the transformer and the arrestor is small. 3. Transformer and the arrestor have a common interconnecting ground. 4. Spark over voltage of the arrestor is greater than the residual voltage. a. 1, 3 and 4 are correct b. 2 and 3 are correct c. 2, 3 and 4 are correct d. 1 and 4are correct The reflection coefficient of a shortcircuited line is a. -1 b. +1 c. 0.5 d. zero The propagation constant of a transmission line is: 0.15 ×10−3 + j1.5 ×10−3 The wavelength of the traveling wave is 1.5 ×10−3 a. 2π 2π b. 1.5 ×10−3 1.5 ×10−3 c.

d. 106.

107.

108.

109.

1 ⎡0.16 0.5 ⎤ 2 ⎢⎣ 0.08 0.24 ⎥⎦ 1 ⎡ 0.16 −0.08⎤ c. 2 ⎢⎣ −0.08 0.24 ⎥⎦ 1 ⎡0.16 0.4 ⎤ d. 2 ⎢⎣ 0.4 0.8⎥⎦ b.

110.

π π

1.5 ×10−3 Hollow conductors are used in transmission lines to a. Reduce weight of copper b. Improve stabi1ity c. Reduce corona d. Increase power transmission capacity

15 of 16 In the solution of load-flow equations, Newton Raphson (NR) method is superior to the Gauss-Seidel (OS) method, because the a. Time taken to perform one iteration in the NR method is less when compared to the time taken in the GS method b. Number of iterations required in the NR method is more when compared to that in the GS method c. Number of iterations required is not independent of the size of the system in the NR method d. Convergence characteristics of the NR method are not affected by the selection of slack bus In a synchronous generator, a divided winding rotor is preferable to a conventional winching rotor because of a. Higher efficiency b. Increased steady-state stability limit c. Higher short-circuit ratio d. Better damping A power system network consists of three elements 0 – 1, 1 2 and 2 – 0 of per unit impedances 0.2, 0.4 and 0.4 respectively. Its bus impedance matrix is given by 1 2 1 ⎡ 7.5 2.5⎤ a. 2 ⎢⎣ −2.5 5.0 ⎥⎦

111.

Zero sequence currents can flow from a line into a transformer bank if the windings are in a. Grounded star/delta b. Delta/star c. Star/grounded star d. Delta/delta When a line-to-ground fault occurs, the current in a faulted phase is 100 A. The zero sequence current in this case will be a. zero b. 33.3 A c. 66.6 A

112.

113.

114.

d. 100 A When a 50 MVA, 11kV, 3-phase generator is subjected to a 3-phase fault, the fault current is –j5 pu (per unit). When it is subjected to a line-to-line fault, the positive sequence current is –j4 pu. The positive and negative sequence reactance’s are respectively a. j 0.2 and j 0.05 pu b. j 0.2 and j 0.25 Pu c. j 0.25 and j 0.25 Pu d. j 0.05 and j 0.05 pu The power generated by two plants are: P1=50 MW, P2=40 MW. If the loss coefficients are B11 = 0.001, B22 = 0.0025 and B12 = – 0.0005, then the power loss will be a. 5.5 MW b. 6.5 MW c. 4.5 MW d. 8.5 MW Given that Vm = maximum value of the phase voltage, the average value of the dc voltage for a 3-phase 3-pulse, uncontrolled rectifier is given by

116.

117.

118.

3 3 Vm a. Vd = 2π b. Vd =

3 3

c. Vd =

3

d. Vd =

115.

π

Vm

Vm

π

3

π

Vm

The following data pertain to two a1tematot working in parallel and supplying a total load of 80 MW: Machine 1:40 MVA with. 5% speed regulation Machine 2:60 MVA with 5 % speed regulation. The load sharing between machines 1 and 2 will be: P1 P2 a. 48 MW 32 MW b.

P1 P2 40 MW 40 MW

c. 30 MW d. 48 MW

119.

120.

16 of 16 The combined frequency regulation of machines in area of capacity 1500 MW and operating at a nominal frequency of 60 kHz is 0.1 pu on its own base capacity. The regulation in HZ/MW will be a. 0.1/1500 b. 60/1500 c. 6/1500 d. 60/150 The per unit impedance of a synchronous machine is 0.242. If the base voltage is increased by 1.1 times, the per unit value will be a. 0.266 b. 0.242 c. 0.220 d. 0.200 The following figure shows the single line diagram of a power system with all reactance’s marked in per unit (pu) on the same base

The system• is on no-load when a 3-phase fault occurs at ‘F’ on the high voltage side of the transformerT2. The fault current will be a. – j 0.8187 pu b. + j 0.8187 pu c. – j8.1871 pu d. +j8.1871 pu Rated breaking capacity (MVA) of a circuit breaker is equal to a. The product of rated breaking current (kA) and rated voltage (kV) b. The product of rated symmetrical breaking current (kA) and rated voltage (kV) c. The product of breaking current (kA) and fault voltage (kV) d. Twice the value of rated current (kA) and rated voltage (kV) If, in a short transmission line, resistance and inductance are found to be equal and regulation appears to be zero, then the load will a. Have unity power factor b. Have zero power factor c. Be 0.707 leading d. Be 0.707 lagging

I.E.S-(OBJ) 1998

1 of 15

ELECTRICAL ENGINEERING PAPER-II 1.

2.

3.

4.

5.

If a 230 V dc series motor is connected to a 230 V ac supply, a. the motor will vibrate violently b. the motor will run with les efficiency and more sparking c. the motor will not run d. the fuse will be blown The interpoles in dc machines have a tapering shape in order to a. reduce the overall weight b. reduce the saturation in the interpole c. economise on the material required for interpoles and their windings. d. increase the acceleration of commutation Consider the following statements: At starting, the field excitation of a dc shunt motor is kept at its maximum value to reduce 1. sparking at brushes 2. acceleration time. 3. starting current. 4. voltage dip in supply. of these statements a. 1 and 2 are correct b. 2, 3 and 4 are correct c. 1,3 and 4 are correct d. 1,2,3 and 4are correct As compared to the use of a single series dc motor for electric traction for a given starting time t. the series-parallel control using two similar motors with time t/2 for each series and parallel operation would give a saving in starting energy of a. 100% b. 50 % c. 25 % d. Zero Consider the following statements:

6.

7.

Permanent magnet dc motors used in cassette tape recorder have 1. magnets on stator and armature on the rotor. 2. magnets on the rotor and armature on the stator. 3. electronic commutation and no brushes. 4. mechanical commutation and brushes. 5. automatic speed governors. Of these statements a. 1, 3 and 5 are correct b. 1, 4 and 5 are correct c. 2, 3 and 5 are correct d. 1 and 4 are correct Two single-phase transformers with turns ratios 1 and 2 respectively are connected to a 3-phase supply on the primary side as shown in the figure. The voltmeter V2, will read

a. 100 V b. 173 V c. 200 V d. 265 V In a 3-phase figure, the secondary corresponding be

a. zero

transformer shown in the phase displacement of line voltages with primary line voltages will

8.

9.

10.

11.

12.

b. 300 lag c. 30° lead d. 180° Three 3-phase transformers each rated at 75 MVA, 132 kV/1 kV, have the following different methods of cooling.: 1. Self oil cooled 2. Forced oil cooled. 3. Forced air cooled. The correct sequence in ascending order in terms of the weights of these transformers is a. 1,2,3 b. 2, 3, 1 c. 3, 1, 2 d. 3, 2, 1 A single-phase induction regulator is a constant input transformer to obtain smooth variation of the output voltage by varying the a. ratio of turns between primary and secondary windings b. frequency c. flux density in the core d. angle between the magnetic axes of the primary and secondary windings An auto-transformer having a transformation ratio of 0.8 supplies a load of 10 kW. The power transferred inductively from the primary to the secondary is a. 10 kW b. 8 k W c. 2kW d. Zero If the dimensions of all the parts of a synchronous generator, and the number of field and armature turns are doubled, then the generated voltage will change by a factor of a. 1 b. 2 c. 4 d. 8 Consider the following statements The effects of slot harmonics are 1. skewing the slots

13.

14.

15.

16.

17.

2 of 15 2. fractional slot winding. 3. short - chorded winding 4. distributed winding. Of these statements a. 1 and 2 are correct b. 2, 3 and 4 correct c. 1, 3 and 4 are correct d. 1 and 3 are correct Which one of the following methods would give a higher than actual value of regulation of an alternator? a. ZPE method b. MMF method c. EMF method d. ASA method A turbo alternator set feeds power to a 3phase constant-voltage, constantfrequency bus. If the steam supply to the set is cut off, then the set will a. continue to run at rated sped in the same direction b. continue to run at a reduced speed in the same direction c. run at rated speed in the reverse direction d. come to a stop An ideal synchronous motor has no starting torque because the a. rotor is made up of salient poles b. relative velocity between the stator and the rotor mmf’s is zero c. relative velocity between stator and rotor mmf’s is not zero d. rotor winding is highly reactive A synchronous motor is operating on noload at unity power factor. If the field current is increased, the power factor will become a. leading and the current will decrease b. lagging and the current will increase c. lagging and the current will decrease d. leading and the current will increase A 3-phase induction machine draws active power ‘P’ and reactive power ‘Q’ from the grid. If it is operated as a generator, P’ and Q will respectively be a. positive and negative

18.

b. negative and negative c. positive and positive d. negative and positive The deep bar rotor of an induction motor is considered equivalent to a double cage rotor for the purposes of starting and performance. At the time of starting, the current distribution in deep bar rotor slot will be as shown in

23.

24. 19.

20.

21.

22.

A 3-phase induction motor fed f a 3-phase voltage controller is suitable for driving loads whose torque is a. constant irrespective of speed b. inversely proportional to the square of speed c. directly proportional to the square of speed d. inversely proportional to speed A 3-phase induction motor is used as an adjustable speed drive from zero to 2.0 per unit speed using a variable frequency inverter. In the speed range of 1.0 to. 2.0 per unit, in order to ensure satisfactory operation. Which one of the following sets of quantities is to be maintained approximately constant? a. Voltage and power b. Flux and torque c. Voltage and torque d. Flux and power A 3-phase slip-ring induction motor has chopper controlled resistance in the rotor circuit. Its power factor and efficiency can be characterised respectively as a. good and poor b. poor and good c. good and good d. poor and poor A 3-phase slip-ring induction motor when started picks up speed but runs stably at about half the normal speed. This is because of a. unbalance in the supply voltages

25.

26.

3 of 15 b. non-sinusoidal nature of the supply voltage c. stator circuit asymmetry d. rotor circuit asymmetry The phenomenon of crawling in a 3-phase cage induction motor may be due to a. unbalance supply voltages b. 7th space harmonic of air-gap field c. 7th time harmonic of voltage wave d. 5th space harmonic Zero sequence impedance of a 3-phase cage induction motor is due to a. stator circuit 3rd time harmonic b. stator circuit 3rd space harmonic c. rotor circuit 3rd time harmonic d. rotor circuit 3rd space harmonic Consider the following statements: Star-delta starter is used in 3-phase. induction motor because it 1. prevents heating of the motor windings. 2. ensures permissible minimum starting current. 3. is regulated by electricity authorities. 4. ensures smooth run-up to full speed. Of these statements : a. 1, 2 and 3 are correct b. 2, 3 and 4 are correct c. 1, 3 and 4 are correct d. 1 and 2 are correct Match List-I (Types of motor) with List-II (Applications) and select the correct answer using the codes given below the lists : List-I A. Shaded pole motor B. Capacitor motor C. Permanent magnet motor D. Steppermotor List-II 1. Robotics 2. Rockets 3. Ceiling fan 4. Table fan A B C D

27.

28.

29.

30.

a. 4 3 1 2 b. 3 4 2 1 c. 3 4 1 2 d. 4 3 2 1 Hysteresis motors are used for Hi-Q record players because of their a. constant (synchronous) speed b. extremely steady torque c. insensitivity to supply voltage fluctuations d. non-dependence on centrifugal switch requirement Which of the following are the features of a shaded pole motor? 1. Salient-pole stator. 2. Uniform air-gap 3. Two stator windings one of which is a short-circuited ring 4. Squirrel cage rotor. Select the correct answer using the codes given below: a. 1 and 4 b. 2 and 4 c. 1, 3 and 4 d. 1, 2 and 3 A hydel power plant of run-off-river type should be provided with a pondage so that the a. firm-capacity of the plant is increased b. operating head is controlled c. pressure inside the turbine casing remains constant d. kinetic energy of the running water is fully utilised If within an untransposed 3-phase circuit of a transmission lines the series impedance of each of the conductors is considered, it is found to contain resistive ⎛d ⎞ terms of the form K 1og, ⎜ 12 ⎟ K being a ⎝ d13 ⎠ constant and d12 and d11 etc. being spacings between the conductors. These terms represent power transfer from one phase to another. The sum of these terms over the three phases is a. three times the average b.

3 times the average

31.

32.

33.

4 of 15 c. one-third of the average d. zero Match List-I (parameter) with List-II (Effects) and select the correct answer using the codes given below the Lists: List-I A. Percent power lost in transmission B. For a given current density, the conductor size C. Power handling capacity of a line at a given voltage D. Surge impedance of a transmission line List-II 1. Decreases with system Voltage 2. Reduces with line length 3. Remains independent of line length 4. Increases with line length A B C D a. 1 2 4 3 b. 3 4 2 1 c. 3 2 4 1 1 4 2 3 d. “Expanded ACSR” are conductors composed of a. larger diameter individual strands for a given cross-section of the aluminium strands b. larger diameter of the central steel strands for a given overall diameter of the conductor c. larger diameter of the aluminium strands only for a given overall diameter of the conductor d. a filler between the inner steel and the outer aluminium strands to increase the overall diameter of the conductor Which of the following are the advantages of interconnected operation of power systems? 1. Less reserve capacity requirement. 2. More reliability. 3. High power factor. 4. Reduction in short-circuit level. Select the correct answer using the codes given below; a. 1 and 2 b. 2 and 3

34.

35.

36.

c. 3 and 4 d. 1 and 4 Steady-state stability of a power system is improved by a. reducing fault clearing time b. using double circuit line instead of single circuit line c. single pole switching d. decreasing generator inertia Equal area criterion gives the information regarding a. stability region b. absolute stability c. relative stability d. swing curves With a number of generators of MVA capacities S1, S2, S3 ………………Sn and inertia constants H1, H2 …………Hn,, respectively connected to the same bus bar in a station, the inertia constant of the equivalent machine on a base of Sb is given by

39.

40.

n

a.

∑H S i

i =1 n

b.

Sb

∑S i =1 n

c.

i =1 n

d.

i =1

37.

38.

.H i

b

Si

∑S

.H i

i

Si

∑S

i

b

.

1 Hi

The critical clearing time of a fault in power systems is related to a. reactive power limit b. short-circuit current limit c. steady-state stability limit d. transient stability limit The use of fast acting relays and circuit breakers for clearing a sudden short-circuit on a transmission link between a generator and the receiving-end bus improves the transient stability of the machine because the a. short-circuit current becomes zero b. post-fault transfer impedance attains a value higher then that during the fault

41.

42.

5 of 15 c. ordinate of the post-fault power-angle characteristic is higher than that of during-fault characteristic d. voltage behind the transient reactance increases to a higher value Consider the following statements: The transient stability of the power system under unbalanced fault conditions can be effectively improved by 1. Excitation control 2. phase-shifting transformer 3. single-pole switching of circuit breakers 4. increasing the turbine input. Of these statements a. 1 and 2 are correct b. 2 and 3 are correct c. 3 and 4 are correct d. 1 and 3 are correct The non-uniform distribution of voltage across the units in a string of suspension type insulators is due to a. unequal self-capacitance of the units b. non-uniform distance of separation of the units from the tower body c. the existence of stray capacitance between the metallic junctions of the units and the tower body d. non-uniform distance between the cross-arm and the units Whenever the conductors are dead-ended or there is a change in the direction of transmission line, the insulators used are of the a. pin type b. suspension type c. strain type d. shackle type Consider the following statements : In the case of suspension-type insulators, the string efficiency can be improved ‘by 1. using a longer cross arm. 2. using a guard ring. 3. grading the insulator discs. 4. reducing the cross-arm length. Of these statements a. 1, 2 and 3 are correct

43.

44.

45.

46.

b. 2, 3 and 4 are correct c. 2 and 4 are correct d. 1 and 3 are correct In a power system, each bus or node is associated with four quantities, namely 1. real power, 2. reactive power, 3. bus-voltage magnitude and 4. phase-angle of the bus voltage. For load-flow solution, among these four, the number of quantities to be specified is a. an one b. any two c. any three d. all the four Match List-I (Type of relay) with List-Il (For the protection of) and select the correct answer using the codes given below the Lists : List-I A. Buchholtz relay B. Translay relay C. Negative sequence relay D. Directional over current relay List-II 1. Feeder 2. Transformer 3. Generator 4. Long Overhead line A B C D a. 1 2 3 4 b. 2 1 3 4 c. 2 1 4 3 1 2 4 3 d. A line trap in carrier current relaying tuned to carrier frequency presents a. high impedance to carrier frequency but low impedance to power frequency b. low impedance to both carrier and power frequency c. high impedance to both carrier and power frequency d. low impedance to carrier frequency but high impedance to power frequency The basic circuit of circulating current system of protection is shown in the

6 of 15 figure. To improve the through-fault stability, a stabilizing resistor is connected between the points

47.

48.

a. R and P in series b. P and S in series c. P and T in series d. P and Q in parellel One current transformer (CT) is mounted over a 3-phase 3-core cable with its sheath and armour removed from the portion covered by the CT. An ammeter placed in the CT secondary would measure a. the positive sequence current b. the negative sequence current c. the zero sequence current d. three times the zero sequence In connection with the arc extinction in circuit breaker, resistance switching is employed wherein a resistance is placed in parellel with the poles of the circuit breaker as shown in the figure. This process introduces damping in the LC circuit. For critical damping, the value of ‘r’ should be equal to

a.

b. 0.5

C L

c. 0.5

L C

1 2π

L C

d. 49.

C L

Load frequency control is achieved by properly matching the individual machine’s a. reactive powers b. generated voltages

50.

51.

52.

53.

54.

c. turbine inputs d. turbine and generator ratings If a voltage-controlled bus is treated as load bus, then which one of the following limits would be violated? a. Voltage b. Active power c. Reactive power d. Phase angle In a conventional reverse blocking thyristor a. external layers are lightly doped and internal layers are heavily doped b. external layers are heavily doped and internal layers are lightly doped c. the p-layers are heavily doped and nlayers are lightly doped d. the p-layers are lightly doped and the n-layers are heavily doped If the amplitude of the gate pulse to thyristor is increased, then a. both delay, time and rise time would increase b. the delay time would increase but the rise time would decrease c. the delay time would decrease but the rise time would increase d. the delay time would decrease while the rise time remains unaffected In order to obtain static voltage equalization in series- connected SCRs, connections are made of a. one resister across the string b. resistors of different value across each SCR c. resistors of the same value across each SCR d. one resistor in series with the string Consider the following statements : The overlap angle of a phase-controlled converter would ‘increase on increasing, the 1. supply voltage 2. supply frequency 3. load current 4. source inductance Of these statements

55.

56.

7 of 15 a. 1, 2 and 3 are correct b. 2, 3 and 4 are correct c. 1, 2 and 4 are correct d. 1, 3 and 4 are correct Analysis of voltage waveform of a singlephase bridge converter shows that it contains x% of 6th harmonic. The 6th harmonic content of the voltage waveform of a 3-phase bridge converter would be a. less than x% due to an increase in the number of pulses b. equal to x%, the same as that of the single-phase converter c. greater than x% due to changes in the input and output voltages of the converter d. difficult to predict as the analysis of converters is not governed by any generalised theory In a single-phase semi-converter with resistive load and for a firing angle α, each SCR conduction and freewheeling action take place respectively, for a. α, 0° b. π — α, α c. π + α, α

57.

58.

d. π — α, 0° The torque produced by a single phase induction motor fed through an ac voltage controller for speed control is due to a. fundamental component of current as well as harmonics, both odd and even b. fundamental component and even harmonic of current c. fundamental component and odd harmonics of current d. fundamental component of current alone A dc chopper is fed from a constant voltage main. The duty ratio α of the chopper is progressively increased while the chopper feeds a RL load. The per unit current ripple would a. increase progressively b. decrease progressively c. decrease to a minimum value at α = 0.5 and then increase

59.

60.

61.

62.

63.

d. increase to a maximum value at α = 0.5 and then decrease In a two quadrant dc to dc chopper, the load voltage is varied from positive maximum to negative maximum by varying the time ratio of the chopper from a. zero to unity b. unity to zero c. zero to 0.5 d. 0.5.to zero The purpose of feedback transformer and diode in complementary commutated in verters is to a. improve the power factor of the load b. return the trapped energy to source c. improve the input power factor d. adsorb more reactive power from the source Use of a reverse conducting thyristor in place of antiparallel combination of thyristor and feedback diode in an inverter a. effectively minimises the peak commutating current b. decreases the operating frequency of operation c. minimises the effects to lead inductances on the commutation performance d. causes deterioration in the commutation performance A voltage source inverter is normally employed when a. source inductance is large and load inductance is small b. source inductance is small and load inductance is large c. both source and load inductances are small d. both source and load inductances are large Match List-I with List-II and select the correct answer using the codes given below the Lists : List-I A. Freewheeling diode B. Feedback diode C. Current source inverter D. Voltage source inverter

64.

65.

66.

8 of 15 List-II 1. Voltages spikes in the output voltage 2. Peaks in the inverter current 3. Inductive loads of phase-controlled converter 4. Inductive loads of dc to ac inverters A B C D a. 4 3 1 2 b. 3 4 1 2 3 4 2 1 c. d. 4 3 2 1 Match List-I with List-II and select the correct answer using the codes given below the Lists : List-I A. Discontinuous conduction of the converter B. Source inductance of the converter C. Use of free-wheeling diode D. Symmetrical angle control List-II 1. Additional reactive power loading 2. Better displacement factor 3. Poor power factor 4. Unity displacement factor A B C D a. 3 1 2 4 b. 1 3 2 4 c. 1 3 4 2 3 1 4 2 d. Avalanche photodiodes are. preferred over PIN diodes in optical communication systems because of a. speed of operation b. higher sensitivity c. larger bandwidth d. larger power handling capacity The drain source voltage at which the drain current becomes nearly constant is called a. barrier voltage b. breakdown voltage c. pick - off voltage d. pinch-off voltage

67.

68.

69.

In the case of a BJT amplifier, bias stability is achieved by a. keeping the base current constant b. changing the base current In order to keep the IC and VCB constant c. keeping the temperature constant d. keeping the temperature and the base current constant The voltages at V1 and V2 of the arrangement shown in the figure will be respectively

71.

72.

a. 6 V and 5.4V b. 5.4 V and 6 V c. 3 V and 5.4 V d. 6 V and 3 V The best approximation for VC in the circuit shown in the figure will be (assume β to be high)

73.

70.

a. 4 V b. 6.8 c. 8.7 V d. 10.7 V For the full-wave rectifier shown in the figure, the rms voltage across each diode will be (assume the diodes and the transformer to be ideal)

a. 28.28 V

74.

9 of 15 b. 20 V c. 17.98 V d. 14. 12 V A transformer coupled amplifier would give a. maximum voltage gain b. mipedance matching c. maximum current gain d. larger bandwidth Match List-I with List-II and select the correct answer using the codes given below the Lists : List-I A. Class A amplifier B. Class B amplifier C. Class C amplifier D. Class AB amplifier List-II 1. Hi Fidenlity 2. Tuned amplifier 3. Power amplifier 4. Low distortion power 5. amplifier A B C D a. 4 3 2 1 1 2 3 4 b. c. 4 2 3 1 d. 1 3 2 4 The overall bandwidth of two identical voltage amplifiers connected in cascade will a. remain the same as that of a single stage b. be worse than that of a single stage c. be better than that of a single stage d. be better if stage gain is low and worse if stage gain is high If the differential and common mode gains of a differential amplifier are 50 and 0.2 respectively, then the CMRR will be a. 10 b. 49.8 c. 50.2 d. 250

75.

An operational amplifier can be connected as a non-inverting voltage comparator as shown in

78.

10 of 15 A unit positive step is applied at the input of the circuit shown in the figure. After 20 seconds, the output V0 will be

a.

b. 79.

a. + 20 V b. + 10 V c. – 10 V d. – 20 V A clipping circuit is shown in the given Fig. I. Its transfer characteristic will be as shown. in

c.

76.

d. In the circuit shown in the given figure, the output voltage will be

a.

77.

a. 9 V b. 10 V c. 11 V d. 12V The open-loop gain of an operational amplifier is 105. An input signal of 1 m V is applied to the inverting input with the non-inverting connected to the ground. The supply voltages are ±10 V. The output of the amplifier will be a. + 100V b. – 100V c. 10 V (approximately) d. – 10 V (approximately)

b.

c.

d.

80.

Which one of low-pass filter the following correctly depicts the output of a to a pulse input

83.

a. 84.

b.

( A + B) + ( A + B)

c.

( A + B ) AB

11 of 15

d. A + B + AB Which one of the following is an non-valid BCD code? a. 0111 1001 b. 0101 1011 c. 0100 1000 d. 0100 1001

(

The expression X + Y

)( X + Y ) ( X + Y )

is

equivalent to a.

XY

b. XY b. 85.

c. X Y d. XY The output X of the circuit shown in the figure will be

c. a.

AB

b. AB c.

81.

82.

d. The output voltage of the circuit shown in the given figure is

a. 1.0 V b. 1.5 V c. 2.0 V d. 2.5 V The output of an EX-OR gate with A and B as inputs will a.

AB + AB

86.

AB

d. AB The output ‘F of the circuit shown in the given figure is

a.

AB

b. AB c.

AB + AB

d. AB + AB

87.

The block diagram of an AM receiver is shown in the figure. The missing block and its location are respectively

91.

92.

88.

89.

a. BPF at A b. HPF at B c. BPF at C d. LPF at D In the circuit shown in the figure, Q = 0, initially. When clock pulses are applied, the subsequent states of ‘Q’ will be

a. 1,0,1,0…………… b. 0,0,0,0…………… c. 1,1,1,1…………… d. 0, 1,0, 1………….. For the diode matrix shown in the figure, the output Y1 will be

93.

94.

95.

90.

a. X0X2 b. X1X3 c. X1 + X3 d. X0 + X2 If a mod-6 counter is constructed using 3flip-flops, the counter will skip a. 4 counts b. 3 counts c. 2 counts

96.

12 of 15 d. None of the counts Which one of the following is an example of non-vola-tile memory a. Static RAM b. Dynamic RAM c. ROM d. Cache memory Ab RRC instruction in 8085 microprocessor instruction set will affect a. CY, S, Z flags b. CY flag c. S flag d. Z flag In a 8085 microprocessor, the following sequence of instructions is executed : STC CMC MOVE A, B RAL MOVE B,A After the last unstruction the output will a. rotate the contents of the accunulator and store it in B b. get the contents of B register into accumulator and rotate it to left by one bit c. double contents of B register d. manipulate carry in A and B The highest priority in 8085 microprocessor system is a. RST 7.5 b. RST 6.5 c. INTR d. TRAP In 8085 microprocessor system, the direct addressing instruction is a. MOV A, B b. MOV B, OAH c. MOV C, M d. STA addr A fragment of assembly code is given below for 8085 : El MVI 09 SIM

97.

98.

99.

100.

This sequence of instructions a. Enables RST 7.5, RST 6.5 and RST 5.5 b. Enables RST 7.5 and RST 6.5 and disables RST 5.5 c. Enables RST7.5 and disables RST 6.5 and RST 5.5 d. Disables RST 7.5, RST 6.5 and RST 5.5 Consider the following Assembly Language program: MVIA, 30 H ACI, 30H XRA, A POP H After the execution of the above program, the contents of the Accumulator will be a. 30 H b. 60 H c. 00 H d. contents of Stack The rms thermal noise currents of three resistors are I1, 12 and I3 respectively. If these resistors are connected in parallel, the total equivalent noise current ‘I’ will be a. I1 + I2 + I3 b. (I1 + I2 + I3)1/3 c. I21 + 122 + I23 d. √ I1 + I2 + I3 The capacity of channel is given by the a. number of digits used in coding b. volume of information it can take c. maximum rate of information transmitted d. bandwidth required for information In respect of the block diagram shown in the figure, the input power is I m W. The output power P0 will be

a. 2 m W b. 1 m W c. 0.5 m W

101.

102.

13 of 15 d. zero A carrier is simultaneously modulated by two sine waves with modulation indices of 0.4 and 0.3. The resultant modulation index will be a. 1.0 b. 0.7 c. 0.5 d. 0.35 In FM, modulation index mf is equal to (Δ f is the frequency deviation and fm is the modulating signal frequency) a. Δf.f m b.

c. d. 103.

104.

105.

fm Δf Δf fm 1 Δf .f m

The most useful modulation technique for high fidelity audio broadcasting on radio in current practice is a. amplitude modulation b. frequency modulation c. pulse amplitude modulation d. pulse code modulation In a 100% amplitude modulated signal, if the total transmitted power is P, then the carrier power will be 2 a. P 3 1 b. P 2 1 c. P 3 1 d. P 4 Match List-I (Types of analog communication) with List-II (System bandwidth) and select the correct answer using the codes given below the Lists : List-I A. Single sideband AM B. Wideband FM C. Vestigial sideband AM

106.

107.

108.

109.

110.

D. Double sideband AM List-II 1. BW proportional to modulation index 2. Bw = 2x maximum signal frequency, Fmax 3. fmax < BW < 2fmax 4. BW = fmax A B C D a. 1 4 3 2 4 1 3 2 b. c. 1 4 2 3 d. 4 1 2 3 A speech signal occupying the band width of 300 Hz to 3 kHz is converted into PCM format for use in digital communication. If the sampling frequency is 8 kHz and each sample is quantized into 256 levels, than the output bit rate will be a. 3 kb/s b. 8 kb/s c. 64 kb/s d. 256kb/s Message switching in computer communication a. is a store and forward system b. requires a dedicated path between transmitter and receiver c. is used only for long messages d. does not require a buffer at transmitter In order to obtain monochrome display in a colour TV monitor, the green, red and blue colors are respectively added in the proportion a. 0.59, .20, and 0.21 b. 0.60, 0.25 and 0.15 c. 0.59, 0.30, and 0.11 d. 0.60, 0.10 and 0.30 A broadcast radio receiver with IF = 455 kHz is tuned to 1500 kHz. The image frequency will be a. 1045 kHz. b. 1500 kHz c. 1955 kHz d. 2410 kHz Assertion (A) : The winding factor of slot harmonics is equal to that of the fundamental.

111.

112.

113.

14 of 15 Reason (R) : Skewing of the rotor slots of an induction motor reduces the effects of slot harmonics. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : In a cylindrical rotor synchronous machine, the armature reaction flux a Φ is in phase with the armature current I but in a salient-pole machine Φa is not in phase with I. Reason (R) : The reluctances along the direct axis and the quadrature axis being different, the ratios of the mmfs and the respective fluxes in the two cases are not equal. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : One-phase supply can be converted to a 3- phase supply with the help of a suitable transformer. Reason (R) : 3-phase supply can be converted to a 1-phase supply by a suitable transformer. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The concept of self-GMD is applicable for the calculation of inductance of transmission lines. Reason (R) : The radius of a conductor of transmission lines, in the expression for inductance is not the self GMD of the conductor. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false

114.

115.

116.

117.

d. A is false but R is true Assertion (A): The bulk supply into the large urban areas is often carried out by underground cables operating at 132 kV and above. This results in large generation of VARs by the cable and consequent rise in voltage at the receiving end. Reason (R) : These VARs may be neutralised by using series capacitance in the line at appropriate intervals. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : A short length of cable between an overhead line and the substation is effective in reducing the incoming surge voltage. Reason (R) : The surge impedance of the cable is quite low when compared with that of the incoming overhead line. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Residual earth fault relays cannot give satisfactory protection in the case of resonant earthed system. Reason (R) : Earth fault currents are very large. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : During inverter operation of a phase controlled thyristor power converter, the upper value of firing angle range is limited to a value of less than 1800.

118.

119.

120.

15 of 15 Reason (R) : A thyristor requires a definite amount of time to regain forward blocking capability after its current has become zero. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : A 3-phase thyristorised full converter feeding a purely resistive load with delayed firing angle of thyristors will draw reactive power from the ac supply. Reason (R) : The ac supply current at delayed firing angle will be non-sinusoidal and its fundamental component would lad, the supply voltage. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The gain of an RC coupled CE amplifier falls off at low frequencies. Reason (R) : The low frequency response depends on the transistor junction capacitance. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Read only memory (ROM) is a random access memory. Reason (R) : Time taken to access any location of ROM is the same. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT a correct explanation of A c. A is true but R is false d. A is false but R is true

I.E.S-(OBJ) 1999

1 of 14

ELECTRICAL ENGINEERING PAPER–II 1.

2.

A thermal generating station has an installed capacity of 15 MW and supplies a daily load of 10 MW for 12 hours and 5 MW for remaining 12 hours. The plant capacity factor for this station is a. 1 b. 0.75 c. 0.67 d. 0.5 Power output (in kW) of a hydro power station is equal to (Q = discharge in m3/s, q overall. efficiency of the plant, h = head in m, ω = density of water) 75 Qω h a. 0.736 η

0.736 Qω hη 75 750 Qθη c. 0.736 h 0.736 Qhη d. 750 ω Consider following moderators used in nuclear reactors: 1. Graphite 2. Beryllium 3. Heavy water Their correct sequence in increasing order of their neutron absorption cross-sections is a. 1, 3, 2 b. 2, 1, 3 c. 3, 1, 2 d. 3, 2, 1 3-phase alternator rated at 50 MVA, 22 kV has a synchronous reactance per phase of 5 Pu on its thermal rating. The pu value of this reactance on a base of 100 MVA and 220 kV is a. 25 pu b. 12.5 Pu c. 1 pu

5.

6.

b.

3.

4.

7.

8.

9.

d. 0.1 pu A short transmission line has a total resistance of 2Ω, reactance of 3Ω, current of 125 A and pf of 0.8. Regulation in percentage is equal to a. 1.9 b. 0.38 c. 3.8 d. 0.19 A star-connected 3-phase 11 kV. 25 MVA alternators with its neutral grounded through a 0.033 Pu reactance (based on the alternator rating) has positive negative and zero-sequence reactance’s of 0.2 pu, 0.1 pu and 0.1 pu respectively. A single line to ground fault on one of its terminals would result in a fault current of a. 150 MVA b. 125 MVA c. 100 MVA d. 50 MVA Compared to Gauss-Seidel method, Newton-Raphson method takes a. less number of iterations and more time per iteration b. less number of iterations and less time per. iteration c. more number of iterations and more time per iteration d. more number of iterations and less time per iteration An infinite bus of 1 Pu is fed from a synchronous machine having E = 1.1 Pu. If the transfer reactance between them is 0.5 pu, the steady stat? power limit will be a. 1.1 pu b. 0.5 pu c. 2.2 Pu d. 1 pu The positive sequence current for a L - L fault of a 2 kV system is 1400 A, and corresponding current for a L - L - G fault

2 of 14

10.

11.

12.

13.

14.

15.

is 2220 A. The zero sequence impedance of the system is a. 62.75 Ω b. 4.5275 Ω c. 5.275 Ω d. 0.5275 Ω The inertia constant of a 100 MVA, 50 Hz, 4-pole generator is 10 MJ/MVA. If the mechanical input to the machine is suddenly raised from 50 MW to 75 MW the rotor acceleration will be equal to a. 225 electrical degree/s2 b. 22.5 electrical degree/s2 c. 125 electrical degree/s2 d. 12.5 electrical degree/s2 A surge of 260 kV traveling in a line of natural impedance of 500Ω arrives at a junction with two lines of natural and 50Ω impedances of 250Ω respectively. The voltage transmitted in the branch lines is a. 400kV b. 260 kV c. 80 kV d. 40 kV Insulation coordination of UHV lines (above 500 kV) is, done based on a. lightning surges b. lightning surges and switches surges c. switching surges d. None of the above The number of discs in a string of insulators for 400 kV ac overhead transmission line lies in the range of a. 32 to 33 b. 22 to 23 c. 15 to 16 d. 9 to 10 The insulation resistance of a single-core cable is 200 MΩ/km. The insulation resistance for 5 km length is a. 40 MΩ b. 1000 MΩ c. 200MΩ d. 8 MΩ

16.

17.

18.

The equivalent capacitor arrangement of a two-string insulator is shown in the above figure. The maximum voltage that each unit can withstand should not exceed 17.5 kV. The line-voltage of the complete string is a. 17.5 kV b. 33 kV c. 35 kV d. 37.3 kV Consider the following statements: 1. By using bundle conductors in an overhead line, the corona loss is reduced. 2. By using bundle conductors, the inductance of transmission line increases and capacitance reduces; 3. Corona loss causes interference in adjoining communication lines. Which of these statements are correct? a. 1 and 2 b. 2 and 3 c. 1 and 3 d. 1, 2 and 3 Which one of the following sequences of operations represents the rated operating duty cycle of a circuit breaker? (O - open; C - close; t = 3 sec.; T = 3 mm.) a. O – t - C0 – T - CO b. O – CO – t – CO – T – C c. O – C – T – OC – T d. O – CO – T – CO – T - C

3 of 14 With the usual notation, the impedance matrix for the system shown in the above figure is ⎡3 1 ⎤ a. ⎢ ⎥ ⎣1 3⎦

19.

20.

21.

22.

⎡ 3 / 8 −1/ 8⎤ b. ⎢ ⎥ ⎣ −1/ 8 3 / 8 ⎦ ⎡ 6 / 5 4 / 5⎤ c. ⎢ ⎥ ⎣ 4 / 5 6 / 5⎦ ⎡5 4⎤ d. ⎢ ⎥ ⎣4 5⎦ A 3-phase circuit breaker is rated at 2000 MVA, 33 kV; its making current will be a. 35 kA b. 49 kA c. 70 kA d. 89 kA Line trap at coupling capacitors are used for carrier current protection in which a. line trap has high impedance to 50 Hz signal but low impedance to carrier current signal whereas a coupling capacitor has low impedance to 50 Hz signal but high impedance to carrier signal b. line trap has low impedance to 50Hz signal but high impedance to carrier current signal, whereas a coupling capacitor has high impedance to 50 Hz signal but low impedance to carrier signal c. both line trap and coupling capacitor have low impedance to 50 Hz signal but high impedance to carrier current signal d. both line trap and coupling capacitor have high impedance to 50 Hz signal but low impedance to carrier current signal Four alternators, each rated at 5 MVA, 11 kV with 20% reactance are working in parallel. The short-circuit level at bus bars is a. 6.25 MVA b. 20 MVA c. 25 MVA d. 100 MVA

23.

24.

The distribution system shown in the above figure is to be protected by overcurrent system of protection. For proper fault discrimination, directional overcurrent relays will be required at locations a. 1 and 4 b. 2 and 3 c. 1, 4 and 5 d. 2, 3 and 5 If the fault current is 2 kA, the relay setting is 50% arid the CT ratio is 400/5, then plug setting multiplier will be a. 25 b. 15 c. 50 d. 12.5 A three-phase 11/66 kV, delta/star transformer, protected by Merz-price scheme has CT ratio of 400/5 on L.T. side. Ratio of C.T. on H.T. side will be equal to a. 1 : 23 b. 23 : 1 c. 23 :

25.

26.

3

d. 3 : 23 Which one of the following statements in respect of HVDC transmission line is not correct? a. the power transmission capability of bipolar line is almost the same as that of single circuit ac line b. HVDC link line can operate between two ac systems whose frequencies need not be equal c. There is no distance limitation for HVDC transmission by UG cable d. Corona loss is much higher in HVDC transmission line In a 3-phase converter used in HVDC transmission, the three anodes conduct sequentially. Due to overlap caused by the circuit inductance, two anodes conduct simultaneously during the overlap period The output voltage waveform during this period is the

27.

28.

29.

30.

31.

a. voltage of the 1st anode, because the 2nd anode has not completely taken over b. mean of the two anode voltages, as they conduct together c. voltage of the 2nd anode, because the voltage of this anode is greater than that of the 1st d. sum of the 1st and the 2nd anode voltages, because both the anodes are conducting If, for a given alternator in economic operation mode, the incremental cost is given by (0.012P +8) Rs./mwh, dPL / dP = 0.2 and plant λ = 25, then the power generation is a. 1000 MW b. 1250 MW c. 750 MW d. 1500 MW Load frequency control uses a. proportional controllers alone b. integral controllers alone c. both proportional and integral controllers d. either proportional or integral controllers Two generators rated at 200 MW and 400 MW are operating in parallel. Both the governors have a drop of 4%, when the total load is 300 MW They share the load as (suffix ‘1’ is used for generator 200 MW and suffix ‘2’ is used for generator 400 MW) a. P1 = 100 MW and P2 = 200MW b. P1 = 150 MW and P2 = 150 MW c. P1 = 200 MW and P2 = 100 MW d. P1 = 200 MW and P2 = 400 MW Assertion (A): dc series motors are used to drive electric locomotives. Reason (R): dc series motor develop high torque at high speed. a. Both A and Rare true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): If an ac-voltage regulator is feeding and R — L ked, the minimum

firing

angle

φ = tan −1 (ω L / R ) .

α min = φ

4 of 14 where

Reason (R): In an ac voltage regulator feeding R — L load, control is lost if α min < φ .

32.

33.

34.

a. Both A and Rare true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): A 64 input MUX can be built by using eight 8 input multiplexers Reason (R): Any six variable functions can always be implemented by a multiplexer with six address lines. a. Both A and Rare true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The input resistance of a silicon JFET is of the order of tens or huntlreds of megaohms. Reason (R): The gate-source junction of JFET is a reverse biased silicon diode and hence only a very small leakage current flows through the gate. a. Both A and Rare true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The per unit impedance of a synchronous machine is the reciprocal of short-circuit ratio of the machine Reason (R): For the computation of the short-circuit ratio, the field excitation to generate rated voltage on open-circuit should be read from the open-circuit characteristic of the machine. a. Both A and Rare true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true

35.

36.

Assertion (A): The switching function F = Σ(0 - 3, 12 - 15) does not have a unique minimal sum of product form. Reason (R) The switching function F = Σ(0 - 3, 7, 12 - 15) has cyclic prime implicants. a. Both A and Rare true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The maximum possible output frequency of the basic series inverter, using SCR’s T1 and T2 is limited to the resonant frequency. Reason (R): Thyristor T2 can only be fired when thyristor T1 is OFF and vice-versa, otherwise a dead short-circuit will take place across the dc supply. a. Both A and Rare true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true

39.

40.

37.

41.

38.

A 5 V reference is drawn from the circuit shown in the above figure. If the zener diode is of 5 mV and 5 V, then RZ will be a. 50 Ω b. 500 Ω c. 5000 Ω d. 50000 Ω A voltage of 200 cos 100 t is applied to a half-wave rectifier with a load resistance of 5 kΩ. The rectifier is represented by an ideal diode in series with a resistance of 1 kΩ. The maximum value of current, dc component of current and rms value of current will be respectively a. 33.33 mA, 10.61 mA and 16.67 mA

5 of 14 b. 22.22 mA, 8.61 mA and 12.3mA c. 28.33 mA, 14.61 mA and 13.33 mA d. 40 mA, 20 mA and 25 mA The transition capacitance of a diode is 1 nF and it can withstand reverse potential of 400 V.A capacitance of 2 nF which can withstand a reverse potential of 1 kV is obtained by connecting a. two 1 nF diodes in parallel b. six parallel branches with each branch comprising three 1 nF diodes in series c. two 1 nF diodes in series d. three parallel branches with each branch comprising six 1 nF diodes in series

42.

The circuit of a class B push-pull amplifier shown in the above figure. If the peak output voltage VO is 16 V, the power drawn from the dc source would be a. 10 W b. 16 W c. 20 W d. 32 W An FET source follower circuit has gm of 2 m band rd of 50 k . If the source resistance RS is 1 kΩ, the output resistance of the amplifier will be a. 330 Ω b. 450 Ω c. 500 Ω d. 1 k Ω If the counters of INTEL 8253 (programmable interval timer) are loaded with a hew value while counting, then a. the counter will stop counting b. the counter will ignore the new. loaded value d continue to count as per previous loaded value c. the counter will start counting backwards d. counting will restart from the new value of count which has been loaded

6 of 14 43.

44.

45.

46.

47.

Assume VBE = 0.7 V and β = 50 for the transistor in the circuit shown in the above figure. For VCE = 2 V, the value of RB is a. 200 kΩ b. 242 kΩ c. 283 kΩ d. 300 kΩ In the shunt series feedback amplifier, the basic amplifier and the feedback network are parallel connected at the input and series connected at the output. The signal sampled and the summing done will be respectively a. current and current b. current and voltage c. voltage and current d. voltage and voltage A transistor amplifier has a voltage gain of 50, input resistance of 1 kΩ and output resistance of 40 kΩ. The amplifier is now provided 10% negative voltage feedback in series with the input. With feedback, the voltage gain, input resistance and output resistance will be respectively a. 8,7 kΩ and 3 kΩ b. 8.33, 6 kΩ and 6.66 kΩ c. 5.33, 8.33 kΩ and 8.66 kΩ d. 6.66, 8.86 kΩ and 6.66 kΩ In an inverting amplifier, the two input terminals of an ideal Op-amp are at the same potential because a. the two input terminals are directly shorted internally b. the input impedance of the Op-amp is infinity c. CMRR is infinity d. the open-loop gain of the Op-amp is infinity

In the circuit shown in the above figure, the value of output ‘vo’ is a. + 3 V b. - 3 V c. - 7 V d. + 7 V 48.

49.

50.

The Op-amp in the above circuit shows a unity-gain bandwidth of 1 MHz and a dominant pole at 10 Hz. The bandwidth of the non-inverting amplifier will be a. 10 MHz b. 1 MHz c. 250 kHz d. 200 kHz The speed of rotation of a shaft is measured by using a 120 teeth wheel and an inductive pick up. The reading on a digital frequency meter is 3000 with a gating period of 10 micro-seconds. The shaft speed would be a. 750 rpm b. 1500 rpm c. 3000 rpm d. 3600 rpm Consider the following statements 1. A NAND gate is equivalent to an OR gate with its inputs inverted. 2. A NOR gate is equivalent to an AND gate with its inputs inverted. 3. A NAND gate is equivalent to an OR gate with its outputs inverted. 4. A NOR gate is equivalent to an AND gate with its output inverted. Which of these statements are correct? a. 1 and 2

7 of 14 Consider the following statements: The circuit in the above figure is the high frequency equivalent of a CE amplifier, lithe upper cut-off frequency ωH = 1/ T where T = RC, then 1. R = RS = rπ 2. R = RS parallel rπ 3. C = Cπ + Cμ 4. C = Cπ + Cμ (1 + gm RL) Which of these statements are correct? a. 1 and 3 b. 1 and 4 c. 2 and 3 d. 2 and 4

b. 2 and 3 c. 3 and 4 d. 1 and 4 51.

An Op-amp with an open-loop gain of 10,000. Rm =2 kΩ and RO = 5000 is used in the non-inverting configuration as shown in the above figure. The output resistance Rof is a. 250.5 Ω b. 21 Ω c. 2 Ω d. 0.998 Ω

55.

52.

53.

Which one of the gates labelled 1, 2, 3 and 4 in the network shown in the above figure is redundant? a. 1 b. 2 c. 3 d. 4 In a JK flip-flop, J is connected to Q and K is connected to Q outputs. The JK flip-flop converrts into a a. R — S flip-flop b. D flip-flop c. T flip-flop d. clocked R — S flip-flop

56.

57.

54. 58.

The counter shown in the above figure has initially Q2Q1 Q0 = 000. The status of Q2 Q1 Q0 after the first pulse is a. 001 b. 010 c. 100 d. 101 A system which accepts as M-bit word and establishes the state “1” on one and only one of 2M output lines is called a. decoder b. demultiplexer c. multiplexer d. encoder The number of comparators needed in a 4bit flash-type A/D converter is a. 32 b. 15 c. 8 d. 4 in 8085 microprocessor whenever the POP H instruction is executed a. data bytes in the HL pair are stored in the stack b. two data bytes at the top of the stack are transferred to the HL pair

59.

60.

61.

62.

63.

64.

c. two data bytes at the top of the stack are transferred to PC d. two data bytes horn the HL registers that were previously stored on the stack on transferred back to the HL pair A 3-bit resistance ladder D/A (R-2R network) has resistor values of R = 10 kΩ and 20 kΩ. If Vref = 8 V. I0 for a digital input of 111 will be a. 0.1 mA b. 0.2 mA c. 0.7mA d. 1 mA Which one of the following is a correct statements in connection with commands of CMP and CPI a. CMP takes less number of m/c cycles compared to CP1 b. CMP takes more number of m/c cycles compared to CPI c. Both CMP and CPI take the same number of m/c cycles d. CMP takes either less or the same number of m/c cycles as compared to CPI The instruction queue length in INTEL 8086 and 8088 are a. 6 bytes in both processors. b. 4 bytes in both processors. c. 4 bytes in 8086 and 6 bytes in 8088 d. 6 bytes in 8086 and 4 bytes in 8088 A four-bit BCD(DCBA) for numeral 9 can be decoded most economically by the logic operation a. AD b. ABD c. ACD d. ABCD A program accesses ten continuous memory locations. The CPU will take less time if the addressing mode used is a. direct b. implicit c. register indirect d. immediate Match List I (chips related to microprocessors and controllers) with List

8 of 14 II (their function) and select the correct answer: List I A. 8255 A B. 8254 C. 8259 D. i 8096 List II 1. Interrupt controller 2. Microcontroller 3. Counter 4. Pripheral interface Codes; A B C D a. 3 4 2 1 b. 4 3 2 1 c. 4 3 1 2 d. 3 4 1 2 65.

66.

67.

Consider a signal f(x) sampled at t = 0, 1, 2, 3, ……. as shown in the above figure. The expression for the sampled signal is a. {f(x).n} where n = number of samples b. {f(x)δ(t, n)} where δ(t, n) kronek or delta n = 0, 1,2, ……… c. {f(x).Δn} where Δ = constant equal to sample duration d. not possible to write If the clock has a frequency of 5 MHz, then the execution time for ADD memory to register instruction using based indexed relative addressing (result put in register) required is a. 4.8 μs b. 4.9 μs c. 5 μs d. 5.1 μs In conventional AM super heterodyne receivers, the detectors employed to extract intelligence include a. peak detectors b. ratio detectors

68.

69.

70.

c. phase locked loops d. slope detectors The characteristic impedance of a transmission line with series impedance Z ohms per unit length and shunt admittance Y mhos per unit length, is given by a.

(Z +Y )

b.

( Z .Y )

c.

(Z / Y )

d.

(Z / Y )

71.

72.

73.

2

The suitable programmable counter for 8086 microprocessors is a. 8253 chip b. 8254 chip c. 8259A chip d. 8251 chip 70. If two stages with noise figures F1 and F2 and gall-is G1 and G2 are cascaded, the resultant noise figure F will be F −1 a. F1 + 2 G1

b. F1 +

74.

2

75.

76.

F2 − 1 G2

c.

F1 − 1 + F2 G2

d.

F1 − 1 + F2 G1

In TV systems, the modulation methods employed for video and audio signals are a. both amplitude modulation b. both frequency modulation c. respectively amplitude modulation and frequency modulation d. respectively frequency modulation and amplitude modulation For an AM wave having a power of 800 W at its carrier frequency and modulation index of 90%, the power content of each side-band is a. 81W b. 162W c. 200W d. 400W The signal to quantization noise ratio in an n-bit PCM system

77.

78.

9 of 14 a. depends upon the sampling frequency employed b. is independent of the value of n c. decreases with increasing value of n d. increases with increasing value of n A PWM signal can be generated by a. an astable multivibrator b. a monostable multivibrator c. integrating a PPM signal d. differentiating a PPM signal Medium wave radio signal can be received at far off distances at night because a. radio waves travel faster at night b. ground wave attenuation is lower at night c. sky wave is stronger at. Night d. there is no fading at night The fetch and execute instructions are repeatedly executed by the microprocessor until the power is switched OFF The microprocessor enters into a loop described by while power is on do begin fetch the next instruction execute this instruction end These two tasks are sequential. Which one of the following microprocessors does not follow this sequence? a. 8085 b. Z 80 c. 8086 d. 68000 Which one of the, following layers is the service provider for transport layer of OSI model? a. Network layer b. Session layer c. Transport layer of another station d. Physical layer A 4-bit Johnson counter is initialized to 0101. Whenever the state 1011 is reached the counter is reinitialized to 0000 at the next closed active edge. Again when the state 0001 s reached, the counter is initialized back to 0101 at the next clock active edge. The cycle length of the counter is a. 6

10 of 14 b. 8 c. 16 d. 32

a.

3 (V + V

b.

3V1

c.

V ⎞ ⎛ 3 ⎜ V1 + 3 ⎟ 3⎠ ⎝

d.

V12 +

79.

2 1

2 3

)

V32 3

82. 1.

80.

81.

An electromechanical energy conversion device is shown in the above figure. The instantaneous values of armature induced emf, bus bar voltage and armature current are respectively e, v and i, Te, Ta and ωr present external torque, armature developed torque and angular velocity of shaft respectively. Assume that the given directions of parameters in the figure are positive. If the device is working in generating mode then a. all parameters will have the positive direction b. e, v, Te and ωr will have negative direction and others will remain in positive direction c. Ta and i will have negative direction and others will remain in positive direction d. Te and ωr will have negative direction and others will remain in positive direction A torroidal ferromagnetic ring is uniformly wound with copper wire of certain turns. A dc voltage V1 is applied across the winding to cause a uniform flux density in the ring. If the linear dimensions of the ring, number of turns and length of a mean turn are doubled without changing the gauge of the wire, the dc voltage required to be applied across the new winding to produce the same flux density will be a. V1/2 b. V1 c. 2V1 d. 4V1 In a 3-phase star connected generator, if the fundamental and third harmonic rms voltages in each phase are respectively V1 and V3, the line voltage of he generator will be

2.

3.

83.

Three singly-excited electromagnetic structures are shown in the above figures labelled 1, 2 and 3 (R - Rotor, S - Stator). The reluctance torque can be developed in a. 1 and 3 b. 1 alone c. 2 and 3 d. 2 alone Consider the following statements regarding the magnetisation characteristics of a dc generator: 1. It represents the variation of field flux with field current. 2. Variation of open-circuit terminal voltage with field current is independent of speed. 3. It is non-Linear from zero to rated field current. 4. It helps to determine critical field resistance at a given period.

84.

85.

86.

87.

5. It always starts from the origin. Which of these statements are correct? a. 1 and 4 b. 1, 2 and 5 c. 2, 3 and 4 d. 3 and 5 If two 8-pole & machines of identical armatures are wound one with lap winding arid the other with wave winding, then a. wave wound machine will have more rated current and more voltage b. lap wound machines will have more rated voltage and more current c. lap wound machine will have more rated voltage and less current d. wave wound machine will have more rated voltage and less current If the speed of a dc motor increases with load torque, then it is a a. series motor b. permanent magnet motor c. differentially compounded motor d. cumulatively compounded motor Full-load voltage regulation of a power transformer is zero, when power factor of the load is neat a. unity and leading b. zero and leading c. zero and lagging d. unity and lagging In a single-phase transformer, the magnitude of leakage reactance is twice that of resistance of both primary and secondary. With secondary short-circuited, the input power factor is

89.

90.

91.

92.

a. 1/ 2 b. 1/ 5

88.

c. 2/ 5 d. 1/3 If a sinusoidal voltage source is connected to a power transformer, its no-load current would be a. sinusoidal and lagging the voltage by 90° b. sinusoidal and lagging the voltage by less than 90° c. rich in third harmonic and its fundamental would lag the voltage by 90°

93.

11 of 14 d. rich in third harmonic and its fundamental would lag the voltage by less than 90° The zero power factor characteristic for the Potier’s diagram can be obtained by loading the alternator using a. lamp load b. synchronous motor c. water load d. dc motor If all other requirements for parallel operation of transformer are fulfilled, which one of following pairs of threephase transformers, with given VECTOR GROUPS, can be operated in parallel? a. Y d 1 and Yy 0 b. Y d 1 and Dy 11 c. Dd 6 and Dy 1 d. Dd 0 and Dy 11 When short-circuit test on a transformer is performed at 25 V, 50 Hz, the drawn current ‘I1’ is at a lagging p.f. angle of φ1. If the test is performed at 25 V, 25 Hz and the drawn current “I2’ is at a lagging p.f. angle of φ, then a. I2 > I1 and φ2 < φ1 b. I2 > I1 and φ2 < φ1 c. I2 < I1 and φ2 > φ1 d. I2 < I1 and φ2 > φ1 A synchronous motor with negligible armature resistance runs at a load angle of 20° at the rated frequency. If supply frequency is increased by 10%, keeping other parameters constant, the new load angle will be a. 16° b. 18° c. 20° d. 22° A synchronous motor is running from an infinite bus of voltage Vt in steady-stat, at about 50% of its rated load with a powerangle δ1, between Vt and Ef (induced voltage). The load is suddenly decreased to 25%. Ef attains its new steady-state powerangle δ2 with Vt by initially, a. falling behind and making a complete rotation b. advancing and making a complete rotation

94.

95.

96.

c. falling behind, followed by oscillation about δ2 d. advancing, followed by oscillation about δ2 The two-reaction phasor diagram of a salient-pole synchronous generator is considered, where Ia = armature current per phase, X1 = armature leakage reactance per phase, Xd = direct-axis synchronous reactance, Xq = quadrature-axis synchronous reactance and V = generator terminal voltage, taken as reference. The voltage in phase with the direct-axis will be the phasor-sum of a. V + Iara + IaX1 b. V + Iara + IaXd c. V + Iara + IaXq d. V + Iara + Ia(Xd + Xq) Consider the following statements : The syunchronous generators used in thermal power stations have 1. cylindrical rotors 2. slip rings and brushes 3. laminated rotor 4. stator slots in multiples of 6 5. 3-phase star connected stator windings Which of these statements are correct? a. 1, 2, 3 and 4 b. 1, 2, 3 and 5 c. 3, 4 and 5 d. 1, 2, 4 and 5 Match List I with List II and select the correct answer: List I A. Single-phase inductor motor B. 3-phase slip ring induction motor C. 3-phase squirrel cage induction motor List II 1. Rotor resistance starting 2. Not self-starting 3. Auto-transformer starting Codes; A B C 2 1 3 a. 1 2 3 b. 2 3 1 c. 3 1 2 d.

97.

98.

99.

100.

101.

12 of 14 A 3-phase induction motor is driving a content torque load of 1 Pu at 5% slip. It has a maximum torque of 2 Pu at 10% slip. Torque-speed variation in stable zone is assumed to be linear. For the stable operation of the motor, the minimum pu supply volt- age is approximately a. 0.25 b. 0.50 c. 0.707 d. 0.80 Slip test is performed to determine a. Slip b. direct axis reactance and quadrature axis c. positive sequence reactance and negative sequence reactance d. sub-transient reactance Match List I (methods of full-load regulation of 25 MVA alternator at 0.8 Power factor lagging) with list II (% regulation): List I A. emf B. mmf C. ZPF List II 1. 13% 2. 18% 3. 32% A B C 3 1 2 a. 1 3 2 b. 2 3 1 c. d. 1 2 3 100. As compared to DOL starting, a cage induction motor with star-delta starting shall have a. more starting torque b. more starting time c. reduced starting current d. smoother acceleration The speed of a 3-phase induction motor is controlled from 1 pu to 2 pu using a variable frequency inverter. The equivalent circuit parameter most likely to vary is a. stator leakage inductance b. rotor leakage inductance c. magnetizing inductance

d. core loss resistance 102.

107.

103.

104.

105.

106.

The phasor diagram of a synchronous machine connected to an infinite bus is shown i above figure The machine is acting as a a. generator and operating at a lagging power factor b. generator and operating at a leading power factor c. motor and operating at a leading power factor d. motor and operating at a lagging power factor Which one of following statements regarding a capacitor start, capacitor run single-phase induction motor is correct? a. One of the capacitors is in the circuit during starting and both are in the circuit during running b. Both the capacitors are in the circuit during starting and one of them is in the circuit during running c. Both the capacitors are in the circuit during starting and running d. One of the capacitors is in the circuit during starting and the other is in the circuit during running ‘Crawling’ is an in4qction motor is due to a. time harmonics in supply b. slip ring rotor c. space harmonics produced y winding currents d. insufficient starting torque A two-phase servomotor develops maximum torque at a. forward speed of one-half of the synchronous speed b. backward speed of one-half of the synchronous speed c. synchronous speed d. a speed of twice the synchronous speed Static voltage equalization in seriesconnected SCRs is obtained by the use of

108.

109.

110.

111.

13 of 14 a. one resistor across the suing b. resistors of different values across each SCR c. resistors of the value across each SCR d. one resistor in series with the string An SCR has half cycle surge current of rating-of 3000 A for 50 Hz supply. One cycle urge current rating will be a. 1500 A b. 2121.32A c. 4242.64 A d. 6000 A The correct sequence of the given devices in the decreasing order of their speeds. of operation is a. Power BJT power MOSFET, IGBT SCR b. IGBT, power MOSFET, power BJT, SCR c. SCR, power BJT, IGBT, MOSFET d. MOSFET, IGBT, power BJT, SCR Match List I (SMPS topology) with List II (output voltage) and select the correct answer: List I A. Boost B. Buck C. Buck-Boost D. Isolated Buck-Boost List II 1. VO = VD 2. VO = -VD/1-D 3. VO = V/1 - D 4. VO = VD/a(1 - D) A B C D 2 1 3 4 a. 3 1 2 4 b. 2 4 3 1 c. 3 4 2 1 d. Commutation overlap in the phasecontrolled ac to dc converter is due to. a. load inductance b. harmonic content of load current c. switching operation in the converter d. source inductance A three-pulse converter has a freewheeling diode across its load. The operating range of the converter is

112.

113.

114.

115.

116.

a. 0° ≤ α ≤ 150° b. 60° ≤ α ≤ 120° c. 30° ≤ α ≤ 150° d. 180° ≤ α ≤ 360° A single-phase ‘fully controlled Iin’ commutated ac to dc converter operates as an inverter, when a. 0° ≤ α ≤ 90°’ b. 90° ≤ α ≤ 180° c. it supplies to a ‘back emf load d. 90° ≤ α ≤ 180°’and there is a suitable dc source in the load circuit A step up chopper is fed from a 220 V dc source to deliver a load voltage of 660 V. If the non-conduction time of the thyristor is 100 μs, the required pulse width will be a. 100 μs b. 200 μs c. 220 μs d. 660 μs In a type -A chopper, given that source voltage = 100 V d, ON-period = 100 μs, OFF-period = 150 μs and load R = 2Ω, L =5 mH with back emf E = 10 V connected in series for continuities conduction, average output voltage and average output current will be respectively a. 40V and 15 A b. 66.66 V and 28.33 V c. 60 V and 25 A d. 40 V and 20 A If an ac chopper is feeding an inductive load, the firing pulse to the SCR a. may have a width equal to turn ON time of the SCR b. should be a series of pulses of short duration c. should be a single pulse of long duration d. should be a train of pulses of duration equal to the conduction period of the SCR

117.

118.

119.

14 of 14 Full-bridge inverter is shown in the above figure. The maximum rms output voltages ‘Vo’at fundamental frequency is a. 24 V b. 33.94 V c. 43.2 V d. 48 V Which one of the following controls reduces the size of the transformer in a switch mode ac power supply? a. Resonant control b. bidirectional control c. PWM control d. Phase control The output voltages e1 and e2 of two fullbridge inverters are added using output transformer. In order to eliminate the 5th harmonic from output voltage, the phase angle between e1 and e2 should be a. π/3rad b. it/4rad c. π/5rad d. π/6rad In single-phase cyclo-converter, if α1 and α2 are the trigger angles of positive converter and negative converter, then a. α1 + α 2 = π / 2 b. α1 + α 2 = π c. α1 + α 2 = 3π / 2 d. α1 + α 2 = 2π

120.

In a 3-phae to 1-phase cyclo-converter employing 6-pulse bridge circuit, if the input voltage is 200 V per phase the fundamental rms value of output voltage will be 600 a. V

π

b. 300 3V c. d.

300 3

π 300

π

V

V

I.E.S-(OBJ) 2000

1 of 14

ELECTRICAL ENGINEERING PAPER-II 1.

If the bandwidth of ith channel is ‘Wi’ and the total number of channels accommodated in a time interval of T is ‘N’, then the minimum bandwidth ‘Bmin’ for TDM is equal to N

a.

N ∑ wi

6.

i =1

b.

a. 900 kHz b. 450 kHz c. 300 kHz d. 225 kHz In the circuit shown in the given figure, if gm is 0.5 × 10–3, then the current ‘I’ will be

N N

∑w

i

i =1

N

c.

∑w i =1

d.

1 N

∑w i =1

2.

3.

4.

5.

i

i

In a DSB-SC system with 100% modulation, the power saving is a. 50% b. 66% c. 75% d. 100% The noise figure of an amplifier is 6 dB. If the input SI N ratio is 38 dB, then the output S/N ratio will be a. 44dB b. 40dB c. 36 dB V d. 32 dB V The output VR of the ratio detector and the output VF of similar Foster-Seeley discriminator are related as a. VF = VR b. VF > VR c. VF = 0.51 VR d. VF = 2.51 VR Without any filtering, a broadcast station at 1600 kHz is heard together with another station at 2500 kHz on a superheterodyne receiver. The IF employer would have been

7.

8.

9.

a. Is b. 100 Is c. 101 Is d. 200 Is In a delta modulation scheme the step height is 75 mV and step width is 1.5 ms. The maximum slope that the staircase can track is a. 50 V/s b. 55 V/s c. 60 V/s d. 65 V/s Two signals have the same frequency spectrum but different phase function. Their power density spectrum will a. differ in phase b. differ by eωt0 c. differ by ω0 d. be identical For the network shown in the given figure, is the hybrid parameter h21

10.

11.

12.

13.

a.

r2 r1 + r2

b.

r1 + r2 r1 + r2 + r3

c. −

r2 r1 + r2

d. −

r1 r1 + r2

In a dc machine, the armature is always on the rotor unlike an ac machine where it could be either on the stator or rotor, because a. commutation action would otherwise not be possible b. armature reaction demagnetising action would otherwise be more c. otherwise it would not be possible to place compensating winding in pole shoes d. self-starting of dc motor would not be possible otherwise The armature mmf of a dc machine has a. triangular space distribution and rotates at the speed of armature b. trapezoidal space distribution and is stationary in space c. stepped distribution and rotates at the speed of the armature d. triangular space distribution and is stationary in space Consider the following statements : For a level compounded dc generator to run at constant speed, the series field mmf must effectively compensate 1. armature reaction mmf 2. armature resistance voltage drop 3. brush contact voltage drop Which of these statements is/are correct? a. 2 alone b. 1 and 2 c. 1 and 3 d. 1, 2 and 3 Consider the following statements: 1. Interpole windings are connected in series with armature winding

14.

2 of 14 2. Polarity of interpole must be the same as that of the main pole in advance 3. Distortion of the main field under the pole shoes is not affected by the use of interpoles Which of these statements regarding interpole used in dc motors is/are correct? a. 1 and 2 b. 2 and 3 c. 1 and 3 d. 1 alone A series motor drawing an armature current of Ia is operating under saturated magnetic conditions. The torque developed in the motor is proportional to a. 1 / Ia b. 1 / I 2a c. I 2a

15.

16.

17.

d. Ia A dc shunt motor having unsaturated magnetic circuit runs at 1000 rpm with rated voltage. If the applied voltage is half of the rated voltage, the motor will run at a. 2000 rpm b. 1000 rpm c. 750 rpm d. 500 rpm A 200 V dc shunt motor delivers an output of 17 kW with an input of 20 kW. The field winding resistance is 50 Ω and armature resistance is 0.04Ω. Maximum efficiency will be obtained when the total armature copper losses are equal to a. 2632 W b. 3000 W c. 3680 W d. 5232W Match List I with List II and select the correct answer : List I A. Voltage drop test B. Hopkinson’s test C. Swineburne’s test D. Retardation test List II 1. Efficiency

18.

2. Separation of iron and friction losses 3. Open- and short-circuited armature coild 4. Temperature rise A B C D 3 1 4 2 a. b. 2 4 1 2 3 4 1 2 c. d. 2 1 4 3 Match List I with List II and select the correct answer: List I A. Shell type with wound core B. Core type with core of laminated sheets C. Shell type with laminated core D. Core type with wound core List II

20.

21.

3 of 14 c. 198 V d. 390 V A 3-phase alternator is connected to a Dd transformer. The hysteresis and eddy current losses of the transformer are respectively 300 W and 400 W. If the speed of the alternator is reduced by 10%, then the hysteresis and eddy current losses of the transformer will be respectively a. 228 W and 262.44 W b. 243 W and 324 W c. 243 W and 360 W d. 270 W and 400 W In an autotransformer of voltage ratio V1 / V2 and V1 > V2, the fraction of power transferred inductively is V1 a. V1 + V2 b.

V2 V1

c.

V1 − V2 V1 + V2

d.

V1 − V2 V1

1.

22. 2.

3.

The windings of a Q kVA, V1 / V2 volts, three phase Dd core type transformer are reconnected to work as a single-phase transformer, the power rating and the maximum voltage ratio of the new configuration will be respectively a. Q/3 kVA and V1/V2 volts b. 3Q kVA and 3V1 / 3V2 volts c. 2Q kVA and

4.

19.

A B C D 4 3 1 2 a. b. 4 2 1 3 1 2 4 3 c. d. 1 3 4 2 A 10 kVA, 400 V/ 200 V single-phase transformer with a resistance of 3% and a reactance of 6% is supplying a current of 50 A to a resistive load. The voltage across the load is a. 194 V b. 196 V

23.

24.

3 V1 / 3 V2 volts

d. 2/3Q kVA and 2V1 / 2V2 volts The mmf produced by the current of a 3phase induction motor a. rotates at the speed of rotor in the air gap b. is standstill with respect to stator mmf c. rotates at slip speed with respect to stator mmf d. rotates at synchronous speed with respect to rotor A 3-phase slip-ring induction motor is wound for 4 poles on stator and 6 poles on rotor. When 3-phase balanced voltage

25.

26.

27.

28.

source at 50 Hz is applied to the motor, it will run at : a. 1500rpm b. 1000rpm c. 750 rpm d. zero speed If the rotor power factor of a 3-phase induction motor is 0.866, the spatial displacement between the stator magnetic field and the rotor magnetic field will be a. 30° b. 90° c. 120° d. 150° The stator of a 6-pole, 3-phase induction motor is fed from a 3phase, 50 Hz supply which contains a pronounced fifth time harmonic. The speed of the fifth space harmonic field produced by the fifth time harmonic in the stator supply will be a. 200 rpm b. 1500 rpm c. 1000 rpm d. 5000 rpm A 6-pole, 50 Hz wound rotor induction motor when supplied at the rated voltage and frequency with slip-ring opencircuited, developed a voltage of 100 V between any two rings. If the rotor is driven by an external means at 1000 rpm opposite to the direction of stator field, the frequency of voltage across slip-rings will be a. zero b. 50 Hz c. 100 Hz d. 200 Hz In a 3-phase squirrel cage induction motor, skewing of rotor slots reduces a. parasitic torque and noise but increases pullout torque b. parasitic torque and noise but increases starting torque c. noise but increases pullout torque and parasitic torque d. parasitic torque, noise, pullout torque and starting torque

29.

30.

31.

32.

4 of 14 An induction motor and synchronous motor are connected to a common feeder line. To operate the feeder line at unity pf, the synchronous motor should be a. under-excited b. over-excited c. normally excited d. disconnected from the common terminals Consider the following statements regarding the design of distributed armature winding in a 3-phase alternator : 1. It reduces the phase belt harmonics 2. It increases utilisation of armature iron and copper 3. It increases rigidity and mechanical strength of the winding 4. It reduces copper in the overhang of the winding Which of these statements are correct? a. 1, 3 and 4 b. 2, 3 and 4 c. 1, 2 and 3 d. 1, 2 and 4 Match List I (Power factor) with list II (Armature reaction of an alternator) and select the correct answer : List I A. UPF B. ZPF lagging C. ZPF leading D. Intermediate Lagging List II 1. Fully demagnetising 2. Fully magnetising 3. Cross - magnetising 4. Partly cross-magnetising and 5. partly demagnetising A B C D 3 1 4 2 a. 3 1 2 4 b. 1 3 2 4 c. 1 3 4 2 d. ac tachometers are often built with thin metallic drag cup rotor to a. reduce inertia

33.

34.

35.

36.

b. obtain low Q c. make them suitable for high frequency (400 Hz) operation d. eliminate direct coupling between two stator windings In a synchronous machine, damper windings are used to a. help in starting as a motor b. run it as an induction motor c. help in starting as a motor and to reduce hunting d. increase efficiency Match List I with list II and select the correct answer: List I Flux due to A. currents in damper windings B. currents in field windings C. armature currents with unity internal pf D. armature currents with zero pf List II 1. Direct axis synchronous reactance 2. Quadrature axis synchronous reactance 3. Transient reactance 4. Sub-transient reactance A B C D 4 3 1 2 a. b. 3 4 2 1 c. 3 4 1 2 4 3 2 1 d. During the turn - off process of a thyristor, the current flow, does not stop at the instant when the current reaches zeros but continues to flow to a peak value in the reverse direction. This is due to a. commutation failure b. hole storage effect c. presence of reverse voltage across the thyristor d. protective inductance in series with the thyristor Consider the following statements: 1. BJT has lower power losses than MOSFETs. 2. MOSFETs have lower power losses than IGBTs

37.

38.

39.

5 of 14 3. SCRs have lower power losses than MOSFETs and IGBTs Which of these statements are correct? a. 1, 2 and 3 b. 1 and 2 c. 2 and 3 d. 1 and 3 A thyristor converter of 415 V, 100 A is operating at rated load. Details of the. thyristor used are, as follows : ‘ON’ state power loss = 150 W, Thermal resistance Junction to case = 0.01° C/W Case to sink = 0.08° C/W Sink to atmosphere = 0.09° C/W Assume ambient temperature as 35°C. The junction temperature for 100% load is a. 48.5° C b. 54.5° C c. 60° C d. 62° C When compared to those of a symmetrical thyristor, the turn-off time and reverse blocking voltage of an asymmetrical thyristor are respectively a. large and large b. large and small c. small and large d. small and small Match List I (Devices) with List II (Properties) and select the correct answer : List I A. Triac B. Reverse conducting thyristor (RCT) C. Gate turn-off thyristor (GTO) D. Amplifying gate thyristor List II 1. Good di/dt behaviour even at low gate currents 2. Normally provided with a small continuous negative, gate pulse during off state 3. Negative gate pulse for reverse conduction 4. No gate pulse for reverse conduction A B C D

40.

41.

42.

4 3 1 2 a. b. 3 4 2 1 3 4 1 2 c. d. 4 3 2 1 In a 3-phase semi-converter, if the firing angle is less than or equal to 60°, then the duration of conduction of each thyristor and diode would be respectively a. 60° and 60° b. 90° and 30° c. 120° arid 120° d. 180° and 180° A 3-pulse converter feed an RLE Load. The source has a definite inductance causing overlap. The thyristors are ideal. It has an overlap angle ‘μ’ of 200 at the minimum firing angle ‘α’. The current remains constant in the complete range of firing angles. The range of firing angles of the converter would be a. 00 < α < 180° b. 20° < α < 180° c. 200 < α < 160° d. 0° < α < 160° Match List I with List II and select the correct answer List I A. Phase-controlled rectifier feeding RL load with perfect smoothing B. Single-pulse converter feeding RL load C. A constant dc voltage-fed dc to ac inverter feeding RL load D. A constant dc current-fed dc to ac inverter feeding RL load List II 1. Output voltage depends on the values of R and L of the load 2. Depends on firing angle 3. Constant and independent of R and L of the load 4. Depends on firing angle and also impedance angle of the load A B C D 2 3 4 1 a. 1 4 3 2 b. 1 3 4 2 c. 2 4 3 1 d.

43.

44.

45.

46.

47.

6 of 14 In a 2-pulse bridge converter with freewheeling diode, the width of the diode current pulse is (α is the firing angle) a. π + α b. π—α c. π d. 2α A single-phase ac voltage regulator is fed from a 50 Hz supply system. If it supplies a load comprising a resistance of 2 Ω connected in series with an inductance of 6.36 mH, then the range of firing angle ‘α’ providing controlled voltage would be a. 0° < α < 180° b. 450 < α < 1800 c. 900 < α < 1800 d. 0° < α < 45° The most accurate and versatile method of achieving reactive power compensation is by using a. switched capacitors b. fixed capacitor with controlled reactor c. saturable reactor with capacitor bank d. switched capacitor with controlled reactors A voltage source inverter will have better performance if its a. load inductance is small and source inductance is large b. both load and source inductances are small c. both load and source inductances are large d. load inductance is large and source inductance is small Consider the following features: 1. Inherent short-circuit protection 2. Regeneration capability 3. Need for inverter grade thyristors 4. Voltage spikes across the load Which of these are the features associated with current source inverter? a. 1, 2 and 3 b. 2, 3 and 4 c. 1, 3 and 4 d. 1, 2 and 4

48.

A series capacitor commuted inverter can operate satisfactorily a. if

1 R2 > 2 LC 4 L

b. if

1 R2 = 2 LC 4 L

1 R2 < 2 LC 4 L d. irrespective of the values of R, L and C A single-phase full-bridge voltage source inverter operating in square wave mode supplied a purely inductive load. If the inverter time period is T, then the time duration for which the feedback diodes conduct in a cycle is a. T b. T/2 c. T/4 d. T/8 If power P available from a hydro scheme is given by the formula P = 9.81 QH, where Q is the flow rate through the turbine in l / s and H is the head in metres, then P will be in units of a. W b. HP c. kJ/s d. kWH A coal-fired steam power station working at a plant load factor of 80% has one 500 MW generating unit. If the heat content of coal is 2 kWh/kg, the overall plant efficiency is 40% and a train load of coal is 2000 metric tons, then the number of trains required daily for the plant is a. 1 b. 6 c. 10 d. 24 In a nuclear power station using Boiling Water Reactor (BWR), water is used as a. a moderator but not as a coolant b. a coolant but not as a moderator c. both moderator and coolant d. neither moderator nor coolant In a nuclear reactor, chain reaction is controlled by introducing

54.

c. if

49.

50.

51.

52.

53.

55.

56.

57.

58.

7 of 14 a. iron rods b. cadmium rods c. graphite rods d. brass rods In the statement, “In a star/delta transformer, there exists a phase difference between the corresponding of ‘X’ phases of primary and secondary ‘Y’ ”, ‘X’ and ‘Y’ stand respectively for a. 60° and voltages b. 60° and currents c. 30° and voltages d. 30° and currents Which of the following conditions is/are necessary for the parallel operation of two transformers? a. Percentage impedance should be the same b. Polarities of both secondaries should be’ the same c. Voltage ratings should be the same d. All the conditions mentioned above in (a), (b) and (c) The impedance per phase of a 3-phase transmission line; on a base of 100 MVA, 100 kV is 2 pu. The value of this impedance on a base of 400 MVA and 400 kV would be a. 1.5 Pu b. 1.0 pu c. 0.5 pu d. 0.25 Pu The values of A, B, C and D constants for a short transmission line are respectively a. Z, 0, 1 and 1 b. 0, 1, 1 and Z c. 1, Z, 0 and 1 d. 1, 1, Z and 0 The self GMD of a conductor with three strands each of radius ‘r’ arid touching each other is a. r (0.7788 × 2 × 2)1/3 b. r (0.7788 × 2 × 2 × 2) c. r (0.7788 × 2 × 2 × 2)3 d. r (0.7788 × 2 × 2)3

59.

60.

61.

62.

63.

If a short transmission line is delivering to lagging pf load, the sending-end pf would be (notations have their usual meaning) VR cos φ + IR sin φ a. VS

b.

VR cos φ + IR VS

c.

VR cos φ + IR VS

d.

VR sin φ + IR cos φ VS

If the positive, negative and zero sequence reactances of an element of a power system are 0.3, 0.3 and 0.8 respectively, then the element would be a a. synchronous generator b. synchronous motor c. static load d. transmission line An isolated synchronous generator with transient reactance equal to 0.1 pu on a 100 MVA base is connected to the high voltage bus through a step up transformer of reactance 0.1 Pu on a 100 MVA base. The fault level at the bus is a. 1000 MVA b. 500 MVA c. 50 MVA d. 10 MVA If a generator of 250 MVA rating has an inertia constant of 6 MJ/MVA, its inertia constant on 100 MVA base is a. 15 MJ/MVA b. 10.5 MJ/MVA c. 6 MJ/MVA d. 2.4 MJ/MVA An overhead line with surge impedance of 400 Ω is terminated through a resistance ‘R’. A surge travelling over the line will not suffer any reflection at the junction, if the value of R is a. 100 Ω b. 200 Ω c. 400 Ω d. 800 Ω

64.

65.

66.

67.

68.

69.

8 of 14 An overhead line with a surge impedance of 400 Ω is connected to a transformer by a short length of cable of surge impedance 100 Ω. If a rectangular surge wave of 40 kV travels along the line towards the cable, then the voltage, of the wave travelling from the junction of the overhead ,line through the cable towards the transformer would be a. 16 kV b. 24 kV c. 32 kV d. 36 kV Disruptive corona begins in smooth cylindrical conductors in air at NTP if the electric field intensity at the conductor surface goes up to a. 21.1 kV(rms) / cm b. 21.1 kV(peak) / cm c. 21.1 kV(average) / cm d. 21.1 kV(rms) / m Load flow studies involve solving simultaneous a. linear algebraic equations b. non - linear algebraic equations c. linear differential equations d. non-linear differential equations A 12-bus power system has 3 voltage controlled buses. The dimensions of the Jacobian matrix will be a. 21 × 21 b. 21 × 19 c. 19 × 19 d. 19 × 21 An over-current relay, having a current setting of 125% is connected to a supply circuit through a current transformer of ratio 400/5. The pick-up value is a. 6.25 A b. 10 A c. 12.5 A d. 15 A If the inductance and capacitance of a power system are respectively 1 H and 001 μF and the. instantaneous value of interrupted current is 10 A, then the voltage across the breaker contact will be a. 50 kV

70.

71.

72.

73.

74.

75.

b. 57 kV c. 60 kV d. 100 kV A three-phase circuit breaker is rated at’ 2000 MVA; 33 kV. Its making current will be a. 35 kA b. 70 kA c. 89 kA d. 161 kA In Merz Price percentage differential protection of a Δ–Y transformer, the CT secondaries connection in the primary and secondary windings of the transformer would be in the form a. Δ–Y b. Y–Δ c. Δ–Δ d. Y–Y When there is interference in an overhead communication line running parallel and in close proximity to an overhead power Line, the voltage induced in the communication line in the longitudinal and lateral directions by ‘the power line are due to a. magnetic induction and electric induction respectively b. electric induction and magnetic induction respectively c. both magnetic induction and electric induction d. magnetic induction only In the case of a HVDC system, there is a. charging current but no skin effect b. no charging current but skin effect c. neither charging current nor skin effect d. both charging current and skin effect Shunt compensation in an EHV Ine is used to improve a. stability and fault level b. fault level and voltage profile c. voltage profile and stability d. stability, fault level and voltage profile Two alternators each having 4% speed regulation are working in parallel. Alternator ‘1’ is rated for 12 MW and

76.

77.

9 of 14 alternator ‘2’ is rated for 8 MW When the total load is 10 MW the Loads shared by alternators 1 and 2 would be respectively a. 4 MW and 6 MW b. 6 MW and 4 MW c. 5 MW ad 5 MW d. 10 MW and zero The cost function of a 50 MW generator is given by (Pi is the generator, loading) F(Pi) = 225 + 53 Pi + 0.02 Pi2 When 100% loading is a. Rs. 55 per MWh b. Rs. 55 per MW c. Rs. 33 per MWh d. Rs. 33 per MW In terms of power generation and Bmm coefficients, the transmission loss for a two-plant system is (Notations have their usual meaning) a. P 12 B11 + 2 P1P2 B12 + P 22 B22 b. P 12 B11 – 2 P1P2 B12 + P 22 B22 c. P 22 B11 + 2 P1P2 B12 + P 12 B22 d. P 12 B11 + P1P2 B12 + P 22 B22

78.

79.

80.

Assertion (A) : A threshold effect is observed in square law detectors. Reason (R) : Square law detector is nonlinear. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : PSK is inferior to FSK. Reason (R) : PSK requires less bandwidth than FSK. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The op-amp is known for its very high voltage gain and broad bandwidth.

81.

82.

83.

Reason (R) : The op-amp has high R CMRR. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : A MOSFET amplifier offers very high input impedance irrespective of its circuit configuration. Reason (R) : MOSFET has extremely low gate current. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : In a bipolar junction transistor, the emitter region width (in comparison to base region width) is immaterial in the design so long as the base doping is kept lower than the emitter doping. Reason (R) : The emitter injection efficiency is also dependent on both emitter and base region width and their relative dopings. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : On supplying 2-phase voltages to balanced two-phase windings (two identical windings in space quadrature), a rotating field is developed. Reason (R) : The amplitude of rotating field is 1.5 times that of each phase. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true

84.

85.

86.

87.

10 of 14 Assertion (A) : The rotor resistance of a deep bar type cage induction motor is higher than the running resistance. Reason (R) : The extra resistance present in the rotor circuit at starting is cut out by a centrifugal switch during normal running. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : It is easy to parallel power MOSFETs for increased current handling capability. Reason (R) : The ON state resistance of a power MOSFET has a positive temperature coefficient. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : It is strongly recommended that the GTO (Gate Turn— Off thyristor) should not be turned ‘on’ until it has been ‘off’ for a specified time. Reason (R) : There may be poor current sharing between the various cathode islands. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Variable frequency square wave inverter providing variable voltage cannot be operated below 10% of base frequency. Reason (R) : The thyristors get damaged due to high di/dt. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false

88.

89.

90.

91.

d. A is false but R is true Assertion A : Voltage-time insulation coordination curves for the equipment to be protected and the lightning arrester to be employed are used for determining the required insulation levels. Reason (R) : Voltage - time insulation coordination curves indicate the time of arrival of the peak of surge wave at the equipment location. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : In a high- or medium-head hydroelectric power station having a long penstock, a surge-tank is provided near the turbine. Reason (R) : A surge-tank stores additional water to be released during the peak-load period. The main functions of the presentation layer of the OSI model include a. encryption and authentication b. authentication and compression c. compression and coding d. encryption and compression Which one of the following signal combinations will generate MEMR signal? a. IO / M ^ RD

94.

95.

96.

b. IO / M ^ RD c. IO / M ^ RD

92.

93.

d. IO / M ^ RD An ADC normally used in a 3½ digit multimeter is of a. dual slope integration type b. voltage to frequency converter type c. flash (or parallel) type d. successive approximation type Consider the following statements: A tunnel diode is 1. made of Ge or GaAs. 2. an abrupt junction with both sides heavily doped.

97.

11 of 14 3. a hyper abrupt junction with both sides heavily doped. 4. a majority camer device. Which of these statements are correct? a. 1 and 2 b. 3 and 4 c. 1, 3 and 4 d. 1, 2 and 4 The sensitivity of a photodiode depends upon a. light intensity and depletion region width b. depletion region width and excess carrier life time c. excess carrier life time and forward bias current d. forward bias current and light intensity In the pnp transistor circuit shown in the given figure, the transistor is in V, saturation with values of Vbe = 0.7 V, Vce(sat) = 0.3 V and βmin = 20. The value of IC will be

a. 4.7 mA b. 5.3 mA c. 8.6 mA d. 10 mA The mobility of electrons in a material is expressed in units of a. V / s b. m2 / V-s c. m2 / s d. J / K Match List I (Symbols) with List II (Devices) and select the correct answer : List I

A.

100.

B.

C.

98.

99.

D. List II 1. Depletion mode MOSFET 2. p - channel JFET 3. n - channel JFET 4. Enhancement mode MOSFET A B C D 2 1 4 3 a. 4 3 2 1 b. 2 3 4 1 c. 4 1 2 3 d. FET voltage divider bias circuit is shown in the given figure. If ID = 4mA, then VGS and VDS will be respectively.

a. — 3.78 V and 4 V b. 4 V and — 3.78 V c. —3.78 V and —4V d. —4 V and —3.78 V If Vm is peak value of an applied voltage in a half-wave rectifier with a large capacitor across the load, then the peak inverse voltage will be a. Vm / 2 b. Vm 2 Vm c. d. 2Vm

101.

102.

103.

12 of 14 Consider the following features regarding an amplifier: 1. Voltage gain being less than one 2. High input impedance 3. High output impedance 4. High current gain Which of these are the characteristic features of an emitter follower amplifier? a. 1, 2 and 4 b. 1, 2 and 3 c. 1 and 3 d. 2, 3 and 4 The upper cut-off frequencies f21 and f22 of the two stages of a cascaded amplifier are respectively 5 MHz and 3.3 MHz, The equivalent upper cut-off frequency of the cascaded amplifier would be a. 4.16 MHz b. 3.33 MHz c. 2 MHz d. 5 MHz Match List I with List II and select the correct answer : List I A. When bridge oscillator B. Voltage shunt feedback amplifier C. Crystal oscillator D. Current shunt feedback amplifier List II 1. Low output impedance 2. RF frequency range 3. Audio frequency range 4. High input impedance 5. High output impedance A B C D 2 1 3 5 a. 3 4 2 1 b. 5 4 2 1 c. 3 1 2 5 d. An amplifier circuit has an overall current gain of –100 and an input resistance of 10 kΩ with a load resistance of 1 kΩ. The overall voltage gain of the amplifier is a. 5 dB b. 10 dB c. 20 dB

104.

105.

106.

107.

d. 40 dB An op-amp has a common mode gain of 0.01 and a differential mode gain of 105. Its common mode rejection ratio would be a. 10–7 b. 10–3 c. 103 d. 107 The Barkhausen criterion for sustained oscillation is given by a. Aβ = 1 b. |Aβ| ≥ 1 c. |Aβ| < 1 d. ∠Aβ = 180o An op-amp circuit is shown in the given figure. The current ‘I’ is

109.

110.

a. zero b. 6mA c. 10 mA d. 12 mA The waveform of the output voltage ‘V0’ for the circuit shown in the given figure (RC > >1) is a 111.

108.

a. sinusoidal wave b. square wave c. series of spikes d. triangular wave A 10 MHz square wave clocks a 5-bit ripple counter. The frequency of the third flip-flop’s output would be a. 2 MHz b. 1.25 MHz c. 50 MHz d. 615 MHz

112.

13 of 14 The states of a RS flip-flop are given in the following table :

The mode of operation of states 1, 2 and 3 are respectively a. indeterminate, set and reset b. prohibited, set and hold c. set, hold and reset d. hold, set and reset Match List I (Circuits) with List II (Applications) and select the correct answer : List I A. Astable multivibrator B. Schmitt trigger C. Bistable multivibrator List II 1. Counter 2. Sweep generator 3. Voltage to frequency converter 4. Comparator A B C 3 4 1 a. 3 2 1 b. 1 4 3 c. 1 2 3 d. A monostable multivibrator circuit is shown in the given figure. The value of C would be nearly

a. 0.001 μF b. 0.01 μF c. 0.1 μF d. 1 μF A 4-bit modulo 16 ripple counter uses JK flip-flop. If the propagation delay of each

14 of 14

113.

flip-flop is 50 ns, the maximum clock frequency that can be used is a. 20 MHz b. 10 MHz c. 5 MHz d. 4 MHz The circuit shown in the given figure is

a. IO / M , RD , WR , b. S1, S0 , INTA

117.

118.

114.

115.

116.

a. an AND gate b. an OR gate c. a XOR gate d. a NAND gate In the case of a 16-bit processor, a single instruction is enough to process a function. For processing the same function. a. more than one 8-bit processors will be required to work in sequence b. more than one 8-bit processors will be required to work in parallel c. a long sequence of instructions will be required for a 8-bit processor d. the same instruction will do for a 8-bit processor also Consider the following functions of an 8086 microprocessor: 1. Temporary storage of data 2. Storing offset of a memory address in DS 3. String instructions 4. JNLE instructions 5. JCXZ instructions Which of these functions require the use of the SI and DI registers? a. 1, 2 and 3 b. 1, 2 and 4 c. 2, 3 and 5 d. 3, 4 and 5 Which one of the following sets of status signals is used in an 8085 microprocessor to uniquely identify the seven machine cycles ?

119.

120.

c. IO / M , S1, S0 d. S2, S1, S0 Control bus is used for transmitting and receiving control signals between a. processor and key board b. processor and various devices c. processor and memory d. input devices and memory If (BX) = 0158 (DI) = 10A5 Displacement = 1B57 (DS) = 2100 (where DS is used as a segment register) then the effective and physical addresses produced using “RELATIVE BASE INDEXED INDIRECT ADDRESSING” will be respectively a. 2D54 and 23D54 b. 23D54 and 2D54 c. 1B57 and 1CAF d. 1CAF and 1B57 A sequence of instruction is executed as follows : begin decode the instruction fetched; if operand in memory then fetch, operand; execute instructions; end This sequence of instructions has performed a. fetch cycle b. both fetch and execute cycles c. execute and decode cycles d. execute cycle. An 8085 microprocessor based system drives a multiplexed 5-digit, 7-segment display. The digits are refreshed at a rate of 500 Hz. The ON time for each digit (assumed equal) is a. 4 × 10–3 s b. 0.4 × 10–3 s c. 10–2 s d. 2.5 × 10–2 s

I.E.S-(OBJ) 2001

1 of 14

ELECTRONICAL ENGINEERING PAPER-II 1.

2.

3.

4.

The load duration curve for a power station is as shown in the above figure. The reserve capacity in the plant at 70% capacity factor is a. Zero b. 10 MW c. 30 MW d. 50 MW In pump storage hydropower plant, the electrical machine is made to work alternately as generator and motor. The efficiency of the generator working at the same electrical power Level is a. Greater than that as motor b. Equal to that as motor c. Less than that as motor d. Greater or less than that as motor depending on the type of the machine The ABCD constants of a 3-phase transmission line are A = D = 0.8 ∠ 1° B = 170 ∠ 85°Ω C = 0.002 ∠ 90.4°mho The sending end voltage is 400 kV. The receiving end voltage under no-load condition is a. 400 kV b. 500 kV c. 320 kV d. 417 kV In a thermal nuclear reactor 1. The purpose of moderator is to slow dawn fast neutrons produced due to fission 2. The moderator material must have low molecular weight

5.

6.

3. Ordinary water can be used as moderator with natural uranium as fuel 4. The multiplication factor is kept slightly greater than unity during its normal functioning Of these statements a. 1 and 3 are correct b. 3 and 4 are correct c. 1, 2 and 3 are correct d. 1, 2 and 4 are correct If a 250 MVA, 11/400 kV three-phase power transformer has leakage reactance of 0.05 per unit on the base of 250 MVA and the primary voltage of 11 kV, then the actual leakage reactance of the transformer referred to the secondary side of 400 kV is a. 0.8 Ω b. 0.0032Ω c. 0.03125Ω d. 32.0Ω In a short transmission line, voltage regulation is zero when the power factor angle of the load at the receiving end side is equal to a. tan −1 ( X / R ) b. tan −1 ( R / X ) c. tan −1 ( X / Z ) d. tan −1 ( R / Z )

7.

Consider the following statements: Surge impedance loading of a transmission line can be increased by 1. Increasing its voltage level 2. Addition of lumped inductance in parallel 3. Addition of lumped capacitance in series 4. Reducing the length of the line Of these statements a. 1 and 3 are correct b. 1 and 4 are correct c. 2 and 4 are correct d. 3 and 4 are correct

8.

9.

10.

11.

12.

The load current in short circuit calculation are neglected because 1. Short-circuit currents are much larger than load, currents 2. Short circuit currents are greatly out of phase with load currents Which of these statement(s) is/are correct? a. Neither 1 nor 2 b. 2 alone c. 1 alone d. 1 and 2 The surge impedance ‘of a 3-phase, 400 kV transmission line is 400Ω . The surge impedance loading (SIL) is a. 400MW b. 100MW c. 1600MW d. 200MW Two 50 Hz generating units operate in parallel within the same power plant and have the following ratings Unit 1 : 500 MVA, 0.85 power factor, 20 kV, 3000 rpm, H1=5MJ/MVA Unit 2 : 200 MVA, 0.9 power factor, 20 kV, 1500 rpm, H2 = 5 MJ/MVA. The equivalent inertia constant H in MJ/MVA on 100 MVA base is a. 2.5 b. 5.0 c. 10.0 d. 35.0 If a traveling-wave traveling along a lossfree overhead line does not result in any reflection after it has reached the far end, then the far end of the line is a. Open circuited b. Short circuited c. Terminated into a resistance equal to surge impedance of the line d. Terminated into a capacitor The active and the reactive power delivered at the receiving end of a short transmission line of impedance Z∠Ψ are respectively given by VV V2 PR = S R cos ( Ψ − δ ) − R cos Ψ, and Z Z VV V2 QR = S R sin ( Ψ − δ ) − R sin Ψ, with Z Z Vs and VR being the magnitude of voltage at the sending and receiving ends, δ the

13.

14.

15.

16.

2 of 14 power-angle. At the power-limit condition i.e. for maximum PR a. Leading VARs (QR) goes to the load for any values of VS and VR b. Leading VARs (QR) goes to the load ONLY for VS=VR c. Lagging VARs (QR) goes to the load for any values of VS and VR d. Lagging VARs (QR) goes to the load ONLY for VS = VR A traveling wave 400/1/50 means crest value of a. 400 V with rise time of 1/50 s b. 400 kV with rise time 1 s and fall time 50 S c. 400 kV with rise time 1 μs with fall time 50μs d. 400 MV with rise time 1μs and fall time 50μs If a 500 MVA, 11 kV three-phase generator at 50 Hz feeds, through a transfer impedance of (0.0 + J 0.605)Ω per phase, an infinite bus also at 11 kV; then the maximum steady state power transfer on the base of 500 MVA and 11 kV is a. 1.0 Pu b. 0.8 Pu c. 0.5 Pu d. 0.4 Pu Installation of capacitors at suitable locations and of optimum size in a distribution system results in 1. Improved voltage regulation. 2. Reduction in distribution power losses. 3. Reduction of kVA rating of distribution transformers Select the correct answer using the codes given below: a. 1 alone b. 1 and 2 c. 1,2 and 3 d. 3 alone In a three unit insulator string, voltage across the lowest unit is 17.5 kV and string efficiency is 8428%. The total voltage across the string will be equal to a. 8.825 kV b. 44.25 kV c. 88.25 kV d. 442.5 kV

3 of 14 17.

18.

19.

20.

21.

Bundled conductors are used for EHV transmission lines primarily for reducing the a. Corona loss b. Surge impedance of the line c. Voltage drop across the line d. I2R losses The good effect of corona on overhead lines is to a. Increase the line carrying capacity due to conducting ionized air envelop around the conductor b. Increase the power factor due to corona loss c. Reduce the radio interference from the conductor d. Reduce the steepness of surge fronts The principal information obtained from load flow studies in a power system are. 1. Magnitude and phase angle of the voltage at each bus 2. Reactive and real power flows in each of the lines 3. Total power loss in the network 4. Transient stability limit of the system Select the correct answer using the codes given below: a. 1 and 2 b. 3 and 4 c. 1, 2 and 3 d. 2 and 4 Three generators rated 100 MVA, 11 kV have an impedance of 0.15 Pu each. If in the same plant, these generators are being replaced by a single equivalent generator, the effective impedance of equivalent generator will be a. 0.05 pu b. 0.15 pu c. 0.25 Pu d. 0.45 Pu If all the sequence voltages at the fault point in a power system are equal, then the fault is a a. Three-phase fault b. Line to ground fault c. Line to line fault d. Double line to ground fault

23.

24.

25.

22. 26.

A three-phase transformer having zerosequence impedance of Z0 has the zerosequence network as shown in the above figure. The connections of its windings are a. star — star b. delta — delta c. star – delta d. delta — star with neutral grounded Which one of the following relays has the capability of anticipating the possible major fault in a transformer? a. Over current relay b. Differential relay c. Buchholz relay d. Over fluxing relay In a 220 kV system, the inductance and capacitance up to the circuit breaker location are 25mH and 0.025μF respectively. The value of resistor required to be. connected across the breaker contacts which will give no transient oscillations, is a. 25 Ω b. 250Ω c. 500Ω d. 1000Ω Match List I with List II and select the correct answer: List I (Equipments) A. Metal oxide arrester B. Isolator. C. Auto-reclosing C.B D. Differential relay List II (Applications) 1. Protects generator against short circuit faults 2. Improves transient stability 3. Allows C.B. maintenance 4. Provides protection against surges A B C D a. 4 3 2 1 b. 3 4 1 2 4 3 1 2 c. d. 3 4 2 1

29. The operating characteristic of a distance relay in the R-X plane is shown in the above figure. It represents operating characteristic of a a. Reactance relay b. Directional impedance relay c. Impedance relay d. Mho relay 27.

Two power plants interconnected by a tieline as shown in the above figure have loss formula coefficient B11 = 10-3 MW-1. Power is being dispatched economically with plant ‘1’ as 100 MW and plant ‘2’ as 125 MW The penalty factors for plants 1 and 2 are respectively a. 1 and 1.25 b. 1.25 and 1 c. 1 and zero d. Zero and 1

30.

31.

32.

28.

The above diagram shows the layout of a power station having two generators A and B, connected to the 11 kV buses which are also fed through two transformers C and D from a 132 kV grid. The 11 kV buses are interconnected through a reactor R. The reactance’s of A, B, C, D and R are, in p.u. on a common MVA- and kV-base. All the generated voltages in A, B and grid are each 1.0 p.u. and assumed as in phase at the time of fault. The steady state symmetrical fault-current for a 3-phase fault on the 11 kV feeders is a. 10 p.u.

33.

4 of 14 b. 15 p.u. c. 20 p.u. d. 25 p.u. The speed regulation parameter R of a control area is 0.025 Hz/MW and load frequency constant D is 2 MW/Hz. The area frequency response characteristic (AFRC) is, a. 42.0 MW/Hz b. 40.0 MW/Hz c. 20 M/Hz d. 2 MW/Hz In the HVDC system, the ac harmonics which gets effectively eliminated with 12 pulse bridge converters, are a. Triplen harmonics b. Triplen and 5th harmonics c. Triplen, 5th and 7th harmonics d. 5th and 7th harmonics In an electromechanical energy conversion device, the developed torque depends upon a. Stator field strength and torque angle b. Stator field and rotor field strengths c. Stator field and rotor field strengths and the torque angle d. Stator field strength only Consider the following statements: The use o. inter poles in dc machines is to counteract the 1. Reactance voltage 2. Demagnetizing effect of armature mmf in the commutating zone 3. Cross-magnetizing effect of armature mmf in the commutating zone Which of these statement (s) is/are correct? a. 1 and 2 b. 2 and 3 c. 1 and 3 d. 3 alone In an alternator, if m is the number of slots per pole per phase and γ is the slot pitch angle, then the breadth or the distribution factor for the armature winding is sin

γ

2 mγ m sin 2 ⎛ mγ ⎞ b. sin ⎜ ⎟ ⎝ 2 ⎠

a.

m sin

5 of 14

γ

2 mγ sin 2 ⎛ mγ ⎞ sin ⎜ ⎟ ⎝ 2 ⎠ d. ⎛γ ⎞ sin ⎜ ⎟ ⎝2⎠ The current drawn by a 220V dc motor of armature resistance 0.5Ω and back emf 200V is a. 40A b. 44A c. 400A d. 440A Match List I (Type of machine) with List II (Characteristic/application) and select the correct answer: List I A. dc shunt generator B. dc series motor C. Level compounded dc generator D. dc series generator List II 1. Electric tr4action 2. Has good voltage regulation 3. Must have residual flux 4. Used as boosters A B C D a. 4 1 2 3 b. 3 2 1 4 c. 4 2 1 3 3 1 2 4 d. A dc shunt generator when driven without connecting field winding shows an open circuit terminal voltage of 12V. When field winding is connected and excited the terminal voltage drops to zero because a. Field resistance is higher than critical resistance b. There is no residual magnetism in the field. Circuit c. Field winding has got wrongly connected d. There is a fault in armature circuit Match List I (dc motors) with List II (Characteristics labeled 1, 2, 3 and 4) and select the correct answer: List I A. Shunt motor

B. Series motor C. Cumulative compound motor D. Differential compound motor List II

c.

34.

35.

36.

37.

a. b. c. d.

A 3 4 3 4

B 2 1 1 2

C 1 2 2 1

D 4 3 4 3

38.

39.

40.

41.

In the ‘V’ curve shown in the above figure for a synchronous motor, the parameter of x and y coordinates are, respectively a. Armature current and field current b. Power factor and field current c. Armature current and torque d. Torque and field current The advantage of the double squirrel-cage induction motor over single cage rotor is that its a. Efficiency is higher b. Power factor is higher c. Slip is larger d. Starting current is lower An induction motor when started on load does not accelerate up to full speed but runs at 1/7t) of the rated speed. The motor is said to be a. Locking b. Pluming c. Crawling d. Cogging Match List I (Equivalent circuit parameter) with List II (Values) for a 50 MVA three phase alternator arid select the correct answer: List I A. Armature resistance B. Synchronous reactance C. Leakage reactance List II

42.

43.

44.

1. 1 Pu 2. 0.1 Pu 3. 0.01 pu A B C a. 1 2 3 b. 3 1 2 c. 3 2 1 d. 1 3 2 Synchronous condenser means a. A synchronous motor with capacitor connected across stator terminals to improve pf b. A synchronous motor operating at full load with leading pf c. An over-excited synchronous motor partially supplying mechanical load, and also improving. Pf of the system to which it is connected d. An over-excited synchronous motor operating at no-load with leading pf used in large power stations for improvement of pf Match List I with List II aid select the correct answer: List I (Tests) A. No-load and blocked rotor test B. Sumpner’s test C. Swinburne’s test List II (Machines) 1. Transformer 2. Induction motor 3. Synchronous motor 4. dc motor A B C a. 1 4 2 b. 2 1 4 c. 3 4 2 d. 3 1 4 Match List 1 with List II and select the correct answer: List I (Regulation method) A. Synchronous impedance method B. Mmf method C. Zero power factor (ZPF) method D. American standard Association method List II (Relevant phasor) 1. emf phasor 2. Predominantly mmf phasor 3. Both emf and mmf phasors 4. emf and mmf phasors including saturation

45.

46.

47.

48.

49.

6 of 14 A B C D a. 1 2 3 4 b. 1 2 4 3 c. 2 1 3 4 d. 2 1 4 3 In a cylindrical rotor synchronous machine, the phasor addition of stator and rotor mmfs is possib1 because a. Two mmfs are rotating in opposite direction b. Two mmfs are rotating in same direction at different speeds c. Two mmfs are stationary with respect to each other d. One mmf is stationary and the other mmf is rotating The rotor power output of 3-phase induction motor is 15 kW The rotor copper losses at a s1p of 4% will be a. 600W b. 625W c. 650W d. 700W Skewing of the rotor in a three-phase squirrel-cage induction motor reduces a. Noise, parasitic torque, starting torque and pullout torque b. Noise and parasitic torque, but increases starting torque and pullout torque. c. Noise and pullout torque, but increases parasitic torque and starting torque d. Noise, parasitic torque and starting torque, but increases pullout torque In a shaded-pole induction motor, the rotor runs from the a. Shaded portion to the unshaded portion of the pole while the flux in the former leads that of the latter b. Shaded portion to the unshaded portion of the pole while the flux in the former lags that in the latter c. Unshaded portion to the shaded portion while the flux in the former leads that in the latter d. Unshaded portion to the shaded portion while the flux in the former lags that in the latter The torque of a reluctance motor can be effectively increased by a. Increasing reluctance of the magnetic circuit along the direct axis

7 of 14

50.

51.

52.

53.

b. Decreasing the reluctance of the magnetic circuit along the quadrature axis c. Increasing the ratio of the quadrature axis reluctance to direct axis reluctance d. Decreasing the ratio of quadrature axis reluctance to direct axis reluctance The starting current of a 3φ induction motor is 5 times the rated current, while the rated slip is 4%. The ratio of starting torque to full-load torque is a. 0.6 b. 0.8 c. 1.0 d. 1.2 A single-phase transformer when supplied from 220 V, 50 Hz has eddy current loss of 50 W. If the transformer is connected to a voltage of 330V, 50 Hz, the eddy current loss will be a. 168.75 W b. 112.5 W c. 75W d. 50W In case of auto-transformers, which of the following statements are correct? 1. An auto-transformer requires less copper as compared to a conventional, 2-winding transformer of the same capacity. 2. An auto-transformer provides isolation between the primary and secondary windings. 3. An auto-transformer has less leakage reactance as compared to the conventional, 2-winding transformer of the same capacity. Select the correct answer using .the codes given below: a. 1, 2 and 3 b. 1 and 2 c. 1 and 3 d. 2 and 3 If Pc and Psc represent core and full-load ohmic losses respectively, the maximum kVA delivered to load corresponding to maximum efficiency is equal to rated kVA multiplied by a. Pc / Psc

b.

Pc / Psc

c.

( Pc / Psc )

2

d. 54.

( Psc / Pc )

2

For a given amount of kinetic energy to be released by the flywheel of ward-LeonardIlgner control system at a given percentage reduction in speed, the mass of the flywheel would depend upon its radius of gyration rg and its initial peripheral speed Up1 a. Directly proportional to both rg2 and U p21

b. Directly

proportional

to

rg2 ,

but

inversely to U P21 c. Inversely proportional to

rg2 , but

directly to U P21 d. Inversely proportional to both rg2 and U P21

55.

56.

Match list I with list II and select the correct answer: List I (Motors) A. Dc series motor B. Squirrel-cage induction motor C. dc shunt motor List II (Applications) 1. Shearing and pressing 2. Haulage and hoisting 3. Rolling mill A B C 1 2 3 a. 2 3 1 b. 3 1 2 c. 3 2 1 d. Match List 1 (1–φ Rectifier topology – feeding resistive Load) with List II (Average output voltage) and select the correct answer: ( α is the firing angle) A. Uncontrolled - half wave B. Controlled - half wave C. Controlled - full wave D. Semi-controlled full wave List II 1. V peak / π (1 + cos α ) 2. 2V peak / π cos α 3. V peak / π 4. V peak / 2π (1 + cos α ) a.

A 3

B 2

C 4

D 1

57.

58.

59.

60.

61.

b. 1 4 2 3 c. 3 4 2 1 d. 1 2 4 3 Switched reluctance motor means a. Salient pole synchronous motor without excitation winding b. A stepper motor with salient poles c. Synchronous motor with salient poles on stator and rotor d. A steeper motor with closed loop control and with rotor position sensor Assertion (A): In avalanche breakdown, the reverse current sharply increases with voltage due to a field emission. Reason (R): The field, emission requires highly doped p and n regions. a. Both A and R are hue and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): In small signal class ‘A’ amplifier, the output is a magnified replica of the input without any change in frequency. Reason (R): The dc operating point is fixed in class ‘A’ position. a. Both A and R are hue and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): D-latch and edge-triggered D-flip flop (FF are functionally different. Reason (R): In D-latch the output (O) can change while enable (EN) is high. In D-FF the output can change only on the active edge of CLK. a. Both A and R are hue and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): D-flip flops are used to construct a buffer register. Reason (R): Buffer registers are used to store a binary word temporarily. a. Both A and R are hue and R is the correct explanation of A

62.

63.

64.

65.

66.

8 of 14 b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Linear AM detector applied with two amplitude-modulated waves simultaneously, one being very weak with respect to the other, detects only the strong signal. Reason (R): Detector selectivity is increased in the presence of strong signal. a. Both A and R are hue and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Coherent FSK system is preferred over non-coherent FSK. Reason (R): Coherent FSK requires less power than non-coherent FSK. a. Both A and R are hue and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): High frequency power supplies are lightweight. Reason (R): Transformer size get reduced at high frequency. a. Both A and R are hue and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true A speciment of intrinsic germanium with the density of charge carries of 2.5 ×1013/cm3, is doped with donor impurity atoms such that there is one donor impurity atom for ever 106 germanium atoms. The density of germanium atoms is 4.4×1022/cm3. The hole density would be a. 4.4 ×1016 / cm3 b. 1.4 ×1010 / cm3 c. 4.4 ×1010 / cm3 d. 1.4 ×1016 / cm3 In a forward biased photo diode, an increase in incident light intensity causes’ the diode current to

a. b. c. d. 67.

Increase Remain constant Decrease Remain constant while the voltage drop across the diode increases If for intrinsic Silcon at 27°C, the charge concentration and mobilities of freeelectrons and holes are 1.5×1016 per m3, and 0.05 m2/(Vs) 0.13m2/(Vs) respectively, its conductivity will be a. 2.4×10-3 (Ω-m)-1 b. 3.15×10-3 (Ω-m)-1 c. 5×10-4 (Ω-m)-1 d. 4.32×10-4 (Ω-m)-1

72.

68.

73.

69.

A circuit using the .BJT is shown in the above figure, the value of β is a. 120 b. 150 c. 165 d. 166 Bridge rectifiers are preferred because a. They require small transformer b. They have less peak inverse voltage c. They need small transformer and also have less peak inverse voltage d. They have low ripple factor

70. 74.

71.

For the circuit shown in the above figure h11, h12, h21 and h22 are respectively a. – 0.5, 0.5, 0.125 and 6 b. 6, 0.5, – 0.5 and 0.125 c. 0.5, – 0.5, 6 and 0.125 d. 0.125, 6, 0.5 and – 0.5 In an RC coupled amplifier, the gain decreases in the frequency response due to the a. Coupling capacitor at low frequency and bypass capacitor at high frequency

75.

9 of 14 b. Coupling capacitor at high frequency arid bypass capacitor at low frequency c. Coupling junction capacitance at low frequency and coupling capacitor at high frequency d. Device junction capacitor at high frequency and coupling capacitor at low frequency The Darlington pair has a current gain of approximately β2, the voltage gain AV, the input resistance Ri and the output resistance R0. when the Darlington pair is used in the emitter follower configuration, AV, Ri and R0 are respectively a. Very large, very large and very small b. Unity, very large and very small c. Unity, very small and very large d. Very large, very small and very large Match List I with List II and select the correct answer: List I A. hie B. hfe C. hre D. hoe List II (Units/delimitations) 1. Current transfer ratio 2. Ohms 3. Siemens 4. Voltage transfer ratio A B C D a. 2 1 3 4 b. 1 2 4 3 c. 1 2 3 4 d. 2 1 4 3 An amplifier having an output resistance of 4 Ω gives an open circuit output voltage of 6 V (rms). The maximum power that it can deliver to a load is a. 1.5 W b. 2.25 W c. 2.4 W d. 9 W Active load is used in the collector of the differential amplifier of an op-amp to a. Increase the output resistance b. Increase the differential gain Ad c. Increase maximum peak to peak output voltage d. Eliminate load resistance from the circuit

10 of 14 76.

A circuit with op-amp .is shown in the above figure. The voltage V0 is a. 3Vs1 − 6Vs2

77.

78.

For the circuit shown in the above figure, β=100 for the transistor, the transistor will be in a. Cut off region b. Inverse active region c. Active region d. Saturation region “Slope overload” occurs in delta modulation when the a. Frequency of the clock pulses is too low b. Rate of change of analog waveform is too large c. Step size is too small d. Analog signal varies very slowly with time The slew rate of an op-amp is 0.5V/micro sec. The maximum frequency of a sinusoidal input of 2 V rms that can be handled without excessive distortion is a. 3kHz b. 30kHz c. 200kHz d. 2MHz

b. 2Vs1 − 3Vs2 c. 2Vs1 − 2Vs2 d. 3Vs1 − 2Vs2 81.

82.

79. 83.

An op-amp is used in the circuit as shown in the above figure. Current I0 is RL a. Vs × Rs ( RL + Rs ) b. Vs / Rs c. Vs / RL ⎛ 1 1 ⎞ d. Vs ⎜ + ⎟ ⎝ Rs RL ⎠

A sinusoidal waveform can be converted to a square waveform by using a a. Two stage transistorized ovel7driven amplifier b. Two stage diode detector circuit c. Voltage comparator based on op-amp d. Regenerative voltage comparator circuit

84.

For the circuit shown in the above figure, by assuming β=200 and VBE = 0.7V, the best approximation for the collector current Ic in the active region is a. 1 mA b. 2.4 mA c. 3 mA d. 9.6 mA High power efficiency of the push-pull amplifier is due to the face that a. Each transistor conducts on different cycle of the input b. Transistors are placed in CE configuration c. There is no quiescent collector current d. Low forward biasing voltage is required Which one of the following is the output of the high pass filter to a step input? a.

80. b.

11 of 14 d. Delay time 88. c.

d.

89. 85.

For the circuit shown in the above figure, the output F will be a. 1 b. X c. Zero d. X In the CMOS inverter, the power dissipation is a. Low only when VEN is low b. Low only when VEN is high c. High during dynamic operation d. Low during dynamic operation

90.

86.

The Schmitt trigger circuit is shown in the above figure. If Vsat = ± 10 V, the tripping point for the increasing input voltage will be a. 1 V b. 0.893 V c. 0.477V d. 0.416V In Boolean Algebra,

An NMOS circuit is shown in the above figure. The logic function for the output (o/p) is

b.

( A + B ) .C + D.E ( AB + C ) .( D + E )

b. F = AB + AB

c.

A. ( B + C ) .D.E

c. F = AC + AB

d. ABCDE Match List I with List II and select the correct answer: List I (Type of gates) A. ECL B. TTL C. CMOS D. NMOS List II (Values of propagation delay) 1. 5ns 2. 20ns 3. 100 ns 4. 1ns A B C D 1 4 3 2 a. b. 4 1 3 2 1 4 2 3 c.

(

a.

)

If F = ( A + B ) A + C , then a. F = AB + AC

d. F = AA + AB 87.

A switch circuit using the transistor is shown in the above figure. Assume hFE(min) = 20 and f τ = 100MHz. The most dominant speed limitation is brought by a. Rise time b. Fall time c. Storage time

91.

92.

93.

94.

95.

4 1 2 3 d. The length of a bus cycle in 8086/8088 is four clock cycles, T1, T2, T3, T4 and an indeterminate number of wait state clock cycles denoted by Tw. The wait states are always inserted been a. T1 and T2 b. T2 and T3 c. T3 and T4 d. T4 and T1 When RET instruction is executed by any subroutine then a. The top of the stack will be popped out and assigned to the PC b. Without any operation, the calling program would resume from instruction immediately following the call instruction c. The PC will be incremented after the execution of the instruction d. Without any operation, the calling program would resume from instruction immediately following the call instruction, and also the PC will be incremented after the execution of the instruction Consider the following set of 8085 instructions used to read a byte of data from the output of an ADC. The byte represents digital equivalent of analog input voltage Vin applied to ADC when RD is asserted. ADC EQU 30H GETADC: IN ADC RET When RET is executed 1. Op-code of IN is fetched 2. port address 30H is decoded 3. Op-code of IN is decoded 4. I/O read operation is performed The correct sequence of these operations is a. 3, 1, 4, 2 b. 1, 3, 2, 4 c. 1, 3, 4, 2 d. 3, 1, 2, 4 In an AM signal when the modulation index is one, the maximum power Pt, (where Pc is the carrier power) is equal to a. Pc b. 1.5pc c. 2pc d. 2.5pc

96.

12 of 14 In the frequency modulation if f m is modulating frequency, Δf is maximum frequency deviation and B is bandwidth, then a. B = Δf + f m b. B = Δf − f m c. B = 2 ( Δf + f m ) d. B = 2 ( Δf − f m )

97.

98.

In 8085 microprocessor, a number of the form 000XXXXO stored in the accumulator is processed by the programme (Assume Cy = 0) as follows ANI OFFH RAL MOV ANI B,A RAL ANI RAL ADD B The operation carried out by the programme is a. Multiplication of accumulator content by 10 b. Complement of accumulator content c. Multiplication of accumulator content by 9 d. Rotation of accumulator content three times Which one of the following circuits transmits two messages simultaneously in one direction? a. Duplex b. Diplex c. Simplex d. Quadruplex

99.

A DSB suppressed carrier reception is shown in the above figure. If (SNR)i is the S/N ratio for direct (incoherent) detection and (SNR)s is that for (coherent) synchronous detection, then a. (SNR)s = 2(SNR)i b. (SNR)s = (SNR)i c. (SNR)s = 4(SNR)i d. (SNR)s = ½ (SNR)i

100.

101.

102.

An AM super-heterodyne receiver with IF of 455kHz is tuned to the carrier frequency of 1000 kHz. The image frequency is a. 545 kHz b. 1 MHz c. 1455kHz d. 1910 kHz A 4 GHz carrier is amplitude-modulated by a low-pass signal of maximum cut off frequency 1 MHz. If this signal is to be ideally sampled, the minimum sampling frequency should be nearly a. 4 MHz b. 4 GHz c. 8 MHz d. 8 GHz If the modulation index of an AM wave is changed from 0 to 1, the transmitted power a. Increases by 50% b. Increases by 75% c. Increases by 100% d. Remains unaffected

103.

Which one of the following PCM schemes is depicted in the above figure? a. Adaptive DM b. Differential PCM c. Companding d. Delta Modulation

106.

107.

108.

109.

13 of 14 d. Inverter The snubber circuit is used in thyristor circuits for a. Triggering b. dv/dt protection c. di/ dt protection d. Phase shifting It is preferable to use a train of pulse of high frequency for gate triggering of SCR in order to reduce a. dv/dt problem b. di/dt problem c. The size of the pulse transformer d. The complexity of the firing circuit A four quadrant chopper cannot be operated as a. One quadrant chopper b. Cycloconverter c. Inverter d. Bi- directional rectifier Match List I (Waveforms) with List II (Descriptions) and select the correct answer: List I A.

B.

C.

104. D.

105.

The latching current in the above circuit is 4 mA. The minimum width of the gate pulse required turn on the thyristor is a. 6 μs b. 4 μs c. 2 μs d. 1 μs Triac cannot be used in a. ac voltage regulators b. Cycloconverters c. Solid state type of switch

List II 1. Single phase fully controlled ac to dc converter 2. Voltage commuted dc to dc chopper with input dc voltage E 3. Phase voltage of a three phase inverter with 180° conduction and input dc voltage E

110.

111.

112.

113.

4. Line voltage of a three phase inverter with 120° conduction and input dc voltage E 5. Three-phase diode bridge rectifier A B C D a. 3 4 1 5 b. 5 1 4 2 c. 3 1 4 5 d. 5 4 1 2 The total harmonic distortion (THD) of ac supply input current of rectifiers is maximum for a. Single - phase diode rectifier with dc inductive filter b. 3-phase diode rectifier with dc inductive filter c. 3-phase thyristor rectifier with inductive filter d. Single-phase diode rectifier with capacitive filter A single phase ac voltage controller feeding a pure resistance load has a load voltage of 200 V (rms) when fed from a source of 250 V(rms). The input power factor of the controller is a. 0.64 b. 0.8 c. 0.894 d. Difficult to estimate because of insufficiency of data In a thyristor-controlled reactor, the firing angle of thyristor is to be controlled in the range of a. 0° to 90° b. 0° to 180° c. 90° to 180° d. 90° to 270° A 3-phase wound rotor induction motor is controlled by a chopper-controlled resistance in its rotor circuit. A resistance of 2Ω is connected in the rotor circuit and a resistance of 4Ω is additionally connected during OFF periods of the chopper. The average resistance in the rotor circuit for the chopper frequency of 200 Hz is a. 26/5Ω b. 24/5 Ω c. 18/5Ω d. 16/5Ω

114.

115.

116.

117.

118.

119.

120.

14 of 14 The most suitable solid state converter for controlling the speed of the three-phase cage motor at 25 Hz is a. Cycloconverter b. Current source inverter c. Voltage source inverter d. Load commutated inverter In case of voltage source inverter, freewheeling can be avoided for the load of a. Inductive nature b. Capacitive nature c. Resistive nature d. Back emf nature PWM switching is preferred in voltage source inverters for the purpose of a. Controlling output voltage b. Output harmonics c. Reducing filter size d. Controlling output voltage, output harmonics and reducing filter size Which one of the following is NOT the advantage of solids state switching of ac capacitors into ac supply over relay based switching? a. Low transients b. Low losses c. Fast response d. Long life The most suitable device for high frequency inversion in SMPS is a. BJT b. IGBT c. MOSFET d. GTO The quality of output ac voltage of a cycloconverter is improved with a. Increase in output voltage at reduced frequency b. Increase in output voltage at increased frequency c. Decrease in output voltage at reduced frequency d. Decrease in output voltage at increased frequency A cycloconverter is operating on a 50 Hz supply. The range of output frequency that can be obtained with acceptable quality, is a. 0 – 16 Hz b. 0 – 32 Hz c. 0 – 64 Hz d. 0 – 128 Hz

I.E.S (OBJ) - 2002

1 of 13

ELECTRICAL ENGINEERING PAPER–II 1.

2.

3.

4.

5.

A d.c. series motor is accidentally connected to single- phase a.c. supply. The torque produced will be a. of zero average value b. oscillating c. steady and undirectional d. pulsating and unidirectional The ‘synchronous - impedance method’ of finding the voltage regulation by a cylindrical rotor alternator is generally considered a. a pessimistic method because saturation is not considered V b. an optimistic method because saturation is not considered c. a fairly accurate method even if power factor is not taken into account while determining synchronous impedance d. a fairly accurate method when power factor is taken into account while determining synchronous impedance Generally the no-load losses of an electrical machine is represented in its equivalent circuit by a a. parallel resistance with a low value b. series resistance with a low value c. parallel resistance with a high value d. series resistance with a high value The power factor of a synchronous motor a. improves with increase in excitation and may even become leading at higher excitations b. decreases with increase in excitation c. is independent of its excitation d. increases with loading for a given excitation When the excitation of normally operating unloaded salient-pole synchronous motor suddenly gets disconnected, it continues to run as a a. Schrage motor b. Spherical motor c. Switched- reluctance motor

6.

7.

8.

9.

d. Variable - reluctance motor A 6-pole, 3-phase alternator running at 1000 rpm supplies to an 8-pole, 3-phase induction motor which has a rotor current of frequency 2 Hz. The speed at which the motor operates is a. 1000 rpm b. 960 rpm c. 750 rpm d. 720 rpm For maximum current during ‘Slip Test’ on a synchronous machine, the armature and aligns along a. d-axis b. q-axis c. 45° to d-axis d. 45° to q-axis Match List I with List II and select the correct answer: List I (Name of test) A. Open circuit and short circuit tests B. Open circuit and zero power factor tests C. Slip test D. Maximum lagging current test List II (Result) 1. Leakage reactance 2. Direct axis synchronous reactance 3. Quadrature axis synchronous reactance 4. Ratio, of direct axis synchronous reactance to quadrature axis synchronous reactance Codes; A B C D a. 1 2 4 3 b. 1 2 3 4 c. 2 1 4 3 d. 2 1 3 4 A 3-phase 50 MVA 10 kV generator has a reactance of 0.2 ohm per phase. Hence the per-unit value of the reactance on. a base of 100 MVA 25 kV will be

10.

11.

a. 1.25 b. 0.625 c. 0.032 d. 0.32 The results of a ‘Slip Test’ for determining direct-axis (Xd) and quadrature-axis (Xq) reactance’s of a star-connected salient pole alternator are given below phase values: Vmax = 108V ; Vmin = 96V , I max = 12 A, I min = 10 A. Hence the two reactance will be a. Xd = 10.8 ohms and Xq = 8 ohms b. Xd = 9 ohms and Xq = 9.6 ohms c. Xd = 9.6 ohms and Xq = 9 ohms d. Xd = 8 ohms and Xq = 10.8 ohms Stepper motors are widely used because of a. wide speed range b. large rating c. no need for field control d. compatibility with digital systems

16.

12.

17.

13.

14.

15.

A 3-phase transformer having zero sequence impedance Z0 has zero-sequence network as represented in the figure. The connections of its windings are a. star with isolated neutral - delta b. star with grounded neutral- delta c. delta- star with grounded neutral d. delta-delta A 2-phase servomotor in control system a. uses drag - cup rotor b. solid cylindrical rotor without slots or windings c. ordinary squirrel - cage rotor d. slip - ring rotor with inherent low rotor resistance Capacitor in a single-phase induction motor is used for a. improving the power factor b. improving the starting torque c. starting the motor d. reducing the harmonics Match List I with List II and select the correct answer:

18.

19.

2 of 13 List I (Transformer) A. Power transformer B. Auto transformer C. Welding transformer D. Isolation transformer List II (Voltage ratio) 1. 230 V / 230 V 2. 220 V / 240V 3. 400 V / 100V 4. 132 k V / 11 kV Codes; A B C D a. 4 2 3 1 b. 4 2 1 3 2 4 1 3 c. d. 2 4 3 1 A two-winding transformer is used as an auto-transformer. The kVA rating of the auto-transformer compared to the twowinding transformer will be a. 3 times b. 2 times c. 1.5 times d. same A 20 kVA, 2000/200 V, 1-phase transformer has nameplate leakage impedance of 8% Voltage required to be applied on the high - voltage side to circulate full - load current with the lowvoltage winding short-circuited will be a. 16 V b. 56.56 V c. 160 V d. 568.68 V The full-load copper-Loss and iron-loss of a transformer are 6400 W and 5000 W respectively. The copper-loss and iron-loss at half load will be, respectively a. 3200 W and 2500 W b. 3200 W and 5200 W c. 16O0 W and 1250 W d. 1600 W and 5000 W In a 100 kVA, 1100/220 V, 50 Hz single phase trans former with 2000 turns on the high -voltage side, the open- circuit test result gives 220 V, 91 A, 5 kW on low voltage side. The core-loss component of current is, approximately a. 9.1 A

20.

21.

22.

b. 22.7 A c. 45.0 A d. 91 A Match List I with List II and select the correct answer: List I (Types of electrical loads) A. Hoist B. Fans C. Machine Tools (Lathe, Milling machine etc.) D. Loads with fluid friction List II (Torque-speed characteristics) 1. Torque ∝ (speed)2 2. Torque ∝ (speed) 3. Constant Torque 4. Torque ∝ 1/ (speed) Codes; A B C D a. 1 3 2 4 b. 1 3 4 2 3 1 4 2 c. d. 3 1 2 4 For a given torque, reducing the diverterresistance of a d.c. series motor a. increases its speed but armature current remains the same b. increases its speed demanding more armature current c. decreases its speed demanding less armature current d. decreases its speed but armature current remains the same Match List I with list II and select the correct answer: A. List I (Types of motors) B. d.c. series motor C. d.c. shunt motor D. 3-phase induction motor E. Synchronous motor List II (Characteristics) 1. Constant speed 2. High starting torque 3. Low starting torque 4. Poor stability A B C D 2 4 3 1 a. b. 3 1 2 4 2 1 3 4 c.

23.

24.

25.

26.

3 of 13 d. 3 4 2 1 Match List I with list II and select the correct answer: List I A. Commutation B. V-curves C. Free wheeling diode D. Overlap List II 1. Inductive load 2. Capacitive load 3. Interpole 4. Source inductance 5. Synchronous motor Codes; A B C D a. 3 5 1 4 b. 2 4 3 5 c. 3 4 1 5 2 5 3 4 d. Possible three -to - three phase transformer connection for parallel operation is a. Δ - Y to Δ - Y b. Δ - Δ to Δ - Y c. Y – Y to Δ - Y d. Δ - Y to Y - Δ Match list I with list II and select the correct answer: List I A. Silica Gel B. Porcelain C. Mercury D. Fins List II 1. Bushing 2. Buccholz relay 3. Tank 4. Breather Codes; A B C D a. 2 1 4 3 b. 4 3 2 1 2 3 4 1 c. d. 4 1 2 3 A 4 kVA, 400/200 V single-phase transformer has resistance of 0.02 p.u. and reactance of 0.06 p.u. Its actual resistance

27.

28.

29.

and reactance referred to h.v. side, are, respectively a. 0.2 ohm and 0.6. ohm b. 0.8 ohm and 2.4 ohm c. 0.08 ohm and 0.24 ohm d. 2 ohm and 6 ohm A certain R - L series combination is connected across a 50 Hz single-phase a.c. supply. If the instantaneous power drawn was found to be negative for 2 milliseconds in one cycle, the ‘power factor angle’ of the current must be a. 9° b. 18° c. 36° d. 45° Stepper motors are mostly used for a. high power requirements b. control system applications c. very high speed of operation d. very low speed of operation. A delta/star transformer has a phase-tophase voltage transformation ratio of K ⎛ delta phase voltage ⎞ ⎜K = ⎟ star phase voltage ⎠ ⎝

32.

33.

34.

The line -to - line voltage ratio of star/delta connection is given by a. K / 3 b. K

c. K 3 30.

31.

d. 3 /K Two 10 kV/440V, 1-phase transformers of ratings 600 kVA and 350 kVA are connected in parallel to share a load of 800 kVA. The reactances of the transformers, referred to the secondary side are 0.0198 Ω and 0.0304 Ω respectively (resistances negligible). The load shared by the two transformers will, be, respectively a. 484.5 kVA and 315.5 kVA b. 315.5 kVA and 484.5 kVA c. 533 kVA and 267 kVA d. 267 kVA and 533 kVA Two transformers, with equal voltage ratio and negligible excitation current, connected in parallel, share load in the ratio of their kVA rating only, if their p.u. impedances (based on their own kVA) are a. equal

35.

36.

4 of 13 b. in the inverse ratio of their ratings c. in the direct ratio of their ratings d. purely reactive The per-unit impedance of a circuit element is 0.15. lithe base kV and base MVA are halved, then the new value of the per-unit impedance of the circuit element will be a. 0.075 b. 0.15 c. 0.30 d. 0.60 The per-unit impedance of an alternator corresponding to base values 13.2 kV and 30 MVA is 0.2 p.u. The p.u. value of the impedance for base values 13.8 kV and 50 MVA in p.u. will be a. 0.131 b. 0.226 c. 0.305 d. 0.364 Match List I with List II and select the correct answer: List I (Phenomenon) A. Voltage stability B. Transient stability C. Oscillatory instability D. Steady-state Dynamics List II (Dominant features) 1. Power system stabilizer 2. Damping power 3. ‘Angle’ stability 4. Reactive power Codes; A B C D a. 1 3 2 4 b. 4 2 3 1 c. 1 2 3 4 d. 4 3 2 1 For transmission line which one of the following relations is true? a. AD - BC = 1 b. AD - BC = 1 c. AD - BC = - 1 d. AD - BC = 0 For a given base voltage and base voltamp, the per-unit impedance value of an element is X. What will be the per-unit impedance value of this element when the

voltage and volt-amp bases are both doubled? a. 4X b. 2X c. X d. 0.5 X

40.

37. 41.

38.

39.

The reflection coefficient for the transmission line shown in figure at point P is a. + 1 b. 0.5 c. 0 d. - 1 A 3-phase transmission line has its conductors at the corners of an equilateral triangle with side 3 m. The diameter of each conductor is 1.63 cm. The inductance of the fine per phase per km is a. 1.232 mH b. 1.182 mH c. 1.093 mH d. 1.043 mH Match List I with List II and select the correct answer: List I (Design parameters) A. Number of suspension insulator discs B. Permissible sag of transmission line conductor for a given tower C. Corona discharge D. Inductance of transmission line conductor List II (Factor(s) on which they depend) 1. Voltage and Tower footing resistance 2. Voltage 3. Voltage and conductor configuration 4. Conductor configuration and Tower configuration Codes; A B C D a. 1 2 3 4 b. 4 3 2 1 c. 1 3 2 4 d. 4 2 3 1

42.

43.

44.

5 of 13 A cable has inductance of 0.22 mH per km and capacitance of 0.202 μF per km. The surge impedance of the cable is a. 28 Ω b. 33 Ω c. 42 Ω d. 50 Ω For some given transmission line the expression for voltage regulation is given V − VR by s ×100% . Hence, VR a. this must be a ‘short’ line b. this may either be a ‘medium line’ or a ‘short line’ c. this expression is true for any line d. this may either by a ‘medium line’ or a ‘long line’ The capacitance of an overhead transmission line increases with 1. increase in mutual geometrical mean distance 2. increase in height of conductors above ground Select the correct answer from the following a. Both 1 and 2 are true b. Both 1 and. 2 are false c. Only 1 is true d. Only 2 is true Consider the following statements: Addition of lumped capacitances in parallel to a loss-free transmission line increases 1. characteristic impedance * 2. Propagation constant 3. system stability 4. charging current Which of these statements are correct? a. 1 and 3 b. 2 and 4 c. 2, 3 and 4 d. 1, 2 and 4 In a certain single-phase a.c. circuit the instantaneous voltage is given by v = V sin (ωt + 30°) p.u. and the instantaneous current is given, by i = I sin (ωt — 300) p.u. Hence the per-unit value of reactive power is a. 1/4

b. 1/2 c. 45.

46.

47.

48.

49.

3 /4

d. 3 /2 In a multimachine interconnected system, subsequent to a 3- phase fault, the transient stability is examined by a. equal -area criterion b. solution of wing equation c. either by equal - area criterion or by solution of swing equation d. combination of equal - area criterion and solution of swing equation The electrical stiffness of a synchronous generator connected to a very large rid can be increased by a. increasing the excitation or the power angle of the machine b. reducing the excitation or the synchronous reactance of the machine c. increasing the synchronous reactance of the machine d. Operating the generator at a much lower MW level compared to the steady -state limit A. surge of 100 kV travels along an overhead line towards it junction with a cable. The surge impedance for the overhead line and cable are 400 ohms and 50 ohms respectively. The magnitude of the surge transmitted through the cable is a. 11.11 kV b. 22.22 kV c. 12.50 kV d. 82.89 kV A surge voltage rising at 100 kV/μs travels along a Loss-less open-circuited transmission line. It takes 10 μs to reach the open end. The reflected wave from the open end, will be rising at a. 100 kV/μs b. 200 kV/μs c. 1000 kV/μs d. 2000 kV/μs The YBUS matrix of a 100-bus interconnected system is 90% sparse. Hence the number of transmission lines in the system must be a. 450 b. 500

50.

51.

52.

6 of 13 c. 900 d. 1000 Match list I with list II and select the correct answer: List I (Load flow methods) A. Gauss-Siedel load flow B. Newton-Raphson load flow C. Fast decoupled load flow D. Real time load flow List II (System environment) 1. Gauss –Elimination 2. L — U factors 3. Contingency studies 4. Off-line solution Codes; A B C D a. 4 3 2 1 b. 2 1 4 3 c. 4 1 2 3 2 3 4 1 d. Match List I with list II and select the correct answer: List I (Types of relays) A. Negative –sequence relay B. Harmonic - restraint differential relay C. Over-current relay with time - delay D. Mho relay List II (Protective schemes) 1. Distribution feeder protection 2. Long h.t. lines protection 3. Transformer protection 4. Rotor protection of alternators Codes; A B C D a. 4 3 1 2 1 2 4 3 b. 4 2 1 3 c. d. 1 3 4 2 The inverse characteristics of an induction – disc relay are shown below

Match list I with list II and select the correct answer

53.

54.

55.

List I (x, y co-ordinates and parameter) A. x — co-ordinate B. y — co-ordinate C. Parameter List II (Variables) 1. Plug settling voltage 2. Current as multiplier of plug setting 3. Operating time 4. Time multiplier setting 5. Power factor Codes; A B C a. 5 4 1 b. 2 3 4 5 3 4 c. d. 2 4 1 Two generators rated 200 MW and 400 MW having governor droop characteristics of 4% and 5% respectively are operating in parallel. If the generators operate on no load at 50 Hz, the frequency at which they would operate with a total load of 600 MW is a. 48.50 Hz b. 47.69 Hz c. 46.82 Hz d. 49.04 Hz The bonding forces in c9mpound semiconductors, such as GaAs, arise from a. ionic bonding b. metallic bonding c. covalent bonding d. combination of ionic and covalent bonding Consider the following statements in connection with the biasing of semiconductor diodes ; 1. LEDs are used. Sunder forward - bias condition 2. Photodiodes are used under forwardbias condition 3. Zener diodes are used under reversebias condition 4. Variable capacitance diodes are used under reverse-bias condition Which of these statements are correct? a. 1, 2 and 3 b. 1, 2 and 4 c. 2, 3 and 4

56.

7 of 13 d. 1, 3 and 4 The junction capacitance of a linearly graded junction varies with the applied reverse bias Vr as a. Vr−1 b. Vr−1/2 c. Vr−1/3 d. Vr1/2

57.

58.

59.

The diffusion capacitance of a forward biased p+ - n junction diode with a steady current I depends on a. width of the depletion region b. mean lifetime of the holes c. mean lifetime of the electrons d. junction area The modified work function of an nchannel MOSFET is — 0.85 V. If the interface charge is 3 × 10-4 C/m2 and the oxide capacitance is 300 μF/m2, the flat band voltage .is a. - 1.85 V b. - 0.15 V c. + 0.15 V d. + 1.85 V In the circuit shown below,

the average value of vo(t) will be a. 0 b. −Vm / π c. −Vm / 2 d. −Vm 60.

Match list I with List II and select the correct answer: List I (Amplifier’s mode of operation) A. Class A B. Class B C. Class C D. Class D List II (Properties/characteristics) 1. Clips off half. a cycle 2. Leads to most stable biasing circuit 3. Transistor acts as switch

8 of 13

61.

62.

4. Amplification of the resonant frequency only Codes; A B C D a. 1 2 3 4 2 1 4 3 b. c. 1 2 4 3 d. 2 1 3 4 Early effectin BJT refers to a. avalanche breakdown b. thermal runaway c. base narrowing d. Zener breakdown In the circuit shown below, the average value of Vo(t) will be

66.

a. 0 b. −Vm / π c. −Vm / 2 d. −Vm 63.

64.

The Darlington pair is mainly used for a. impedance matching b. wideband voltage amplification c. power amplification d. reducing distortion In the op-amp circuit shown below, vi > 0 and i = Io .eαv. The output vo will be proportiona to a.

67.

the resistance Rg is chosen as R1 | | R2 in order to a. increase gain b. reduce offset voltage c. reduce offset current d. increase CMRR An amplifier of gain A is bridged by a capacitance C as shown below.

The effective input capacitance is a. C/A b. C(1 - A) c. C (1.+ A) d. CA The resolution of a 12 bit Analog to Digital converter in per cent is a. 0.01220 b. 0.02441 c. 0.04882 d. 0.09760

68.

vi

The Boolean expression for the output Y in the logic circuit in a. A B C

b. vi c. ekvi d. l n ( kvi )

b. A B C c.

ABC

d. A B C 69.

65.

In the inverting op-amp circuit shown below, 70.

To add two M-bit numbers, the required number of half adders is a. 2m — 1 b. 2m — 1 c. 2m + 1 d. 2m Consider the following

71.

72.

73.

Any combinational circuit can be built using 1. NAND gates 2. NOR gates 3. DC - OR gates 4. Multiplexeis Which of these are correct? a. 1, 2 and 3 b. 1, 3 and 4 c. 2, 3 and 4 d. 1, 2 and 4 The decimal equivalent of hexadecimal number 2 A OF is a. 17670 b. 17607 c. 17067 d. 10767 The binary equivalent of hexadecimal number 4 F 2 D is a. 0101 1111 0010 1100 b. 0100 1111 0010 1100 c. 0100 1110 0010 1101 d. 0100 1111 0010 1101 A 3-to-8 decoder is shown below:

76.

b. 2050H → 01; 2051H → FF ; H → FF ; L → 01 c. 2050H → FF ; 2051H → 01; H → 01; L → FF d. 2050H → FF ; 2051H → 01; H → 00; L → 00 77.

78.

79.

74.

75.

All the output lines of the chip will be high, when all the inputs 1, 2 and 3 a. are high; and G1, G2 are low b. are high; and G1 is high, G2 is high c. are high; and G1 is low, G2 is high d. are high; and G1 is high, G2 is low Which logical operation is performed by ALU of 8085 to complement a number? a. AND b. NOT c. OR d. EXCLUSIVE OR The number of output pins of a 8085 microprocessor are a. 40 b. 27 c. 21

9 of 13 d. 19 Consider the execution of the following instructions by a 8085 microprocessor LXI H, 01FFH SHLD 2050H After execution the contents of memory locations 2050H and 2051H and the registers H and L, will be a. 2050H → FF ; 2051H → 01; H → FF ; L → 01

80.

81.

Which one of the following functions is performed by the 8085 instruction MOV H, C? a. Moves the contents of H register to C register b. Moves the contents of C register to H register c. Moves the contents of C register to H L pair d. Moves the contents of HL pair to C register For 8085 microprocessor; the instruction RST.6 restarts subroutine at address a. 00H b. 03H c. 30H d. 33H Memory-mapped I/O-scheme for the allocation of address to memories and I/O devices, is used for a. small systems b. large systems c. both large and small systems d. very large systems The interfacing device used for the generator of accurate time delay in a microcomputer system is a. Intel — 8251 b. Intel — 8257 c. Intel — 8253 d. Intel — 8259 Let x(t) be a real signal with the Fourier transform X(f). Let X*(f) denote the complex conjugate of X(f). Then a. X(-f) = X*(f) b. X(-f) = X(f) c. X(-f) = - X(f)

82.

83.

84.

85.

86.

87.

88.

d. X(-f) = - X*(f) Let the transfer function of a network be jθ f H ( f ) = H ( f ) e ( ) = 2e− j 4π f If a signal x(t) is applied to such a network, the output y(t) is given by a. 2x(t) b. x(t - 2) c. 2x(t - 2) d. 2x(t - 4π) The maximum number of quantized amplitude levels, than a 3-digit ternary PCM system can be used to represent is a. 8 b. 9 c. 27 d. 81 The waveform A cos (ω1t + k cos ω2t ) is a. amplitude modulated b. frequency modulated c. phase modulated d. frequency as well as phase modulated Let x(t) = 5 cos (50t + sin 5t). Its instantaneous frequency (in rad/s) at t = 0 has the value a. 5 b. 50 c. 55 d. 250 The performance of the DPCM - Coder improves as the a. input probability density becomes more and more Gaussian b. input power spectral density tends to be white c. input dynamic range increases d. sample-to-sample correlation of the input increases An FM wave uses a 2-5V, 500 Hz modulating frequency and has a modulation index of 50. The deviation is a. 500 Hz b. 1000 Hz c. 1250 Hz d. 25000 Hz Match List I with List II and select the correct answer: List I (Modulation / reception techniques) A. Super heterodyne receiver

89.

90.

91.

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10 of 13 B. FM C. PCM D. Delta modulation List II (Disadvantages) 1. Threshold effect 2. Granular noise 3. Image frequency interference 4. Quantization noise Codes; A B C D 1 3 4 2 a. 3 1 4 2 b. 1 3 2 4 c. d. 3 1 2 4 Consider a binary Hamming code of block length 31 and rate equal to (26/31). Its minimum distance is a. 3 b. 5 c. 26 d. 31 A satellite channel can be fairly accurately modelled as a a. random delay channel b. panic button channel c. additive white Gaussian noise channel d. fading channel One, disadvantage of adaptive delta modulation over linear delta modulation is that it a. requires more bandwidth b. is more vulnerable to channel errors c. requires a large number of comparators in the encoder d. is not suitable for signals with periodic components An MTI radar is operating at the wavelength of 5 × 10-2 m and the pulse repetition frequency (PRF) is 1000. Then the first blind speed (in m/s) occurs at a. 25 b. 50 c. 500 d. 1000 Consider the following statements: If the maximum range of a radar has to be doubled, 1. the peak transmitted power may be increased 16 fold

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2. the antenna diameter may be doubled 3. the sensitivity of the receiver may be doubled 4. the transmitted pulse width may be doubled Which of these statements are correct? a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 1 and 4 With reference to a pulsed radar match List I (Problem) with List II (Causes) and select the correct answer: List I (Problem) A. Second time around echo B. Blind speeds C. Inadequate range resolution D. False –alarms List II (Causes) 1. Broad transmitted pulse 2. Inadequate detection threshold 3. MTI filter 4. Inadequate Inter Pulse period Codes; A B C D 4 3 1 2 a. 1 2 4 3 b. 4 2 1 3 c. 1 3 4 2 d. When cathode of a thyristor is made more positive than its anode a. all the junctions are reverse biased b. outer junctions are reverse biased and central one is forward biased c. outer junctions are forward biased and central one is reverse biased d. all the junctions are forward biased The sharing of the voltages between thyristors operating in series is influenced by the a. di/dt capabilities b. dv/dt capabilities c. junction temperatures d. static v - i characteristics and leakage currents R - C snubber is used in parallel with the thyristor to

11 of 13 reduce dv/dt across it reduce di/dt through it limit current through the thyristor ensure its conduction after gate signal is removed For a step up d.c. - d.c. chopper with an input d.c. voltage of 220 volts, if the output voltage required is 330 volts and the non-conducting time of thyristor is 100 μs the ON time of thyristor would be a. 66.6 μs b. 100 μs c. 150 μs d. 200 μs A thyristor controlled reactor is used to get a. variable resistance b. variable capacitance c. variable inductance d. improved reactor power factor A single-phase full-bridge converter with a free-wheeling diode feeds an inductive load. The load resistance is 15.53Ω and it has a large inductance providing constant and ripple free d.c. current. Input to converter is from an ideal 230 V, 50 Hz single phase source. For a firing delay angle of 60°, the average value of diode current is a. 10 A b. 8.165 A c. 5.774 A d. 3.33 A The operation of an inverter fed induction motor can be shifted from motoring to regenerative braking by a. reversing phase sequence b. reducing inverter voltage c. decreasing inverter frequency d. increasing inverter frequency In a three-phase full wave a.c. to d.c. converter, the ratio of output ripplefrequency to the supply-voltage frequency is a. 2 b. 3 c. 6 d. 12 a. b. c. d.

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A’6-phase bridge-converter feeds a purely resistive load. The delay angle α is measured from the point of naturalcommutation. The effective control of voltage can be obtained when a lies in the range a. 0 ≤ α ≤ 105° b. 0 ≤ α ≤ 120° c. 0 ≤ α ≤ 150° d. 0 ≤ α ≤ 180° a.c. voltage regulators are widely used in a. traction drives b. fan drives c. synchronous motor drives d. slip power recovery scheme of slipring induction motor When fed from a fully controlled rectifier, a d.c. motor, driving an active load, can operate in a. forward motoring and reverse braking mode b. forward motoring and forward braking mode c. reverse motoring and reverse braking mode d. reverse motoring and forward braking mode Compared to a single - phase half-bridge inverter, the output power of a singlephase full-bridge inverter is higher by a factor of a. 12 b. 8 c. 4 d. 2 In a switched-mode power supply (SMPS), after conversion of a.c. supply to a highly filtered d.c. voltage, a switching transistor is switched ON and OFF at a very high speed by a pulse width modulator (PWM) which generates very-high frequency square pulses. The frequency of the pulses is typically in the range of a. 100 Hz - 200 Hz b. 500 Hz – 1 kHz c. 2 kHz – 5 kHz d. 20 kHz - 50 kHz

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12 of 13 How many switches are used to construct a three-phase cycloconverter? a. 3 b. 6 c. 12 d. 18 A 3-phase cycloconverter is used to obtain a variable- frequency single-phase a.c. output. The single phase a.c. load is 220 V. 60 A at a power factor of 0.6 lagging. The rms value of input voltage per phase required is a. 376.2 V b. 311.12 V c. 266 V d. 220 V Assertion (A): Even at no load a large three - phase squirrel- cage. Induction motor is started at reduced voltage. Reason (R): If a large three – phase squirrel -cage induction motor with no load is started at full voltage, it is damaged. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): A single-phase induction motor is not self-starting. Reason (R): A three-phase induction motor is self-starting. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The distribution transformers are designed for minimum core losses. Reason (R): Primary windings of distribution transformers are energized throughout the day. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A

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c. A is true but R is false d. A is false but R is true Assertion (A): The maximum operating temperature of overhead Line conductors made of aluminum or copper is restricted to 75°C. Reason (R): Conductor temperature beyond 75°C may shatter porcelain insulators. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): In the modeling of medium and long transmission lines the nominal-it and T circuits are not equivalent to each other. Reason (R): A star-delta transformation can be used to derive the one circuit from the other. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): When a Line -to-Line (L L) faults takes place at the terminals of an open-circuited generator, phase voltages are sometimes ‘indeterminate’, though line -to- line voltages are always determinable. Reason (R): During a line-to-line fault, zero-sequence voltage is always indeterminate. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): In L. P. S. (Longitudinal Power Supply) system, the voltage regulation is generally poor? Reason (R): L. P. S. system has low level of short-circuit M. V.A. a. Both A and R are true and R is the correct explanation of A

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13 of 13 b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): A tunnel diode can be used as an oscillator. Reason (R): Voltage controlled negative resistance is exhibited by a tunnel diode. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The intrinsic carrier concentration of Si at room temperature is more than that of GaAs. Reason (R): Si is an indirect bandgap semiconductor while GaAs is a direct bandgap semiconductor. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Slope overload is a problem in D.P.C.M. Reason (R): D. P.C. M. makes use of adjacent sample correlations. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Thermal noise in metallic resistors can be characterized by Gaussian probability density function. Reason (R) Power spectral density of thermal noise is essentially constant for a very large frequency range. a. Both A and R are true and R is the correct explanation of A b. Both A and R are true but R is NOT the correct explanation of A c. A is true but R is false d. A is false but R is true

I.E.S-(OBJ) 2003

1 of 15

ELECTRICAL ENGINEERING PAPER-II 1.

2.

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The direction of rotation of V d.c series motor can be reversed a. By interchanging supply terminals b. By interchanging field terminals c. Either by interchanging supply terminals or by interchanging field terminals d. By interchanging supply terminals as well as field terminals Match List I with List II and select the correct answer: List I (Machine) A. DC Motor B. DC Generator C. Alternator D. Induction Motor List II (Graph) 1. Circle Diagram 2. V-Curve 3. Open Circuit Characteristics 4. Speed-Torque Characteristics A B C D a. 4 3 1 2 b. 3 4 2 1 c. 4 3 2 1 d. 3 4 1 2 The current drawn by a 120 V d.c. motor with back e.m.f. of 110 V and armature resistance of 0.4 ohm is a. 4A b. 25A c. 275 A d. 300 A Armature torque of a d.c. motor is a function of which of the following factors? 1. Speed 2. Field Flux 3. Armature Current 4. Residual Magnetism Select the correct answer using the codes given below:

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a. 2 and 3 b. 1 and 4 c. 3 and 4 d. 1 and 2 The dummy coils in d.c. machines are useful to a. Increase the efficiency b. Improve the commutation c. Reduce the cost of the machine d. Maintain mechanical balance of armature The speed of a d.c. shunt motor may be varied by varying 1. Field current 2. Supply voltage 3. Armature circuit Select the correct answer using the codes given below a. 1, 2 and 3 b. 1 and 2 4. 1 and 3 5. 2 and 3 If the field of a synchronous motor is under excited, the power factor will be a. Lagging b. Leading c. Unity d. More than unity Which of the following graphs represents the speed-torque characteristic of a synchronous motor? a.

b.

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c.

12. d.

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Match List I (Machine Components) with List II (Functions) and select the correct answer : List I A. Damper Winding B. Interpole Winding C. End Ring D. Conservator List II 1. Used in synchronous motor to provide starting torque 2. Used in d.c. generator to neutralize the reactance voltage and cross magnetizing effect of armature reaction 3. Used to short circuit rotor bars of cagetype induction motor 4. Used to protect transformers from damage when oil expands due to rise in temperature A B C D a. 2 1 3 4 b. 1 2 4 3 c. 2 1 4 3 d. 1 2 3 4 An induction motor having 8 poles runs at 727.5 r.p.m. If the supply frequency is 50 Hz, the e.m.f. in the rotor will have a frequency of a. 1.5 Hz b. 48.5 Hz. c. 51.5 Hz d. 75 Hz

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2 of 15 The synchronous reactance is the a. Reactance due to armature reaction of the machine b. Reactance due to leakage flux. c. Combined reactance due to leakage flux and armature reaction d. Reactance either due to armature reaction or leakage flux Match List I (Type of AC Winding) with List II (Feature of AC Windings) and select the correct answer : List I A. Single Layer B. Double Layer C. Full Pitch D. Chorded List II 1. Coil span and pole pitch are. equal 2. Coil span is shorter than pole pitch 3. Number of slots is equal to number of coils 4. Number of slots is twice the number of coils A B C D a. 3 4 1 2 b. 4 3 2 1 c. 3 4 2 1 d. 4 3 1 2 Match List I (Machines) with List II (Tests) and select the correct answer : List I A. Transformer V B. DC Motor C. Alternator D. Induction Motor List II 1. Slip Test 2. Blocked Rotor Test 3. Sumpner’s Test 4. Swinburne’s Test A B C D a. 3 4 1 2 b. 4 3 2 1 c. 3 4 2 1 d. 4 3 1 2 The leakage reactance of a three-phase alternator determined by performing

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a. Open circuit and zero power factor tests b. Zero power factor and slip tests c. Open- and short-circuit tests d. Short-circuit and slip tests Consider the following types of singlephase motors: 1. Capacitor start induction motor 2. Capacitor start and run induction motor 3. Permanent split capacitor motor 4. Shaded pole motor The correct sequence of these in the ascending order or magnitude of starting torque is a. 1, 2, 3, 4 b. 2, 3, 4, 1 c. 3, 4, 2, 1 d. 4, 3, 2, 1 Which one of the following statements is correct in respect of an induction motor ? a. The maximum torque will depend on rotor resistance b. Although the maximum torque does not depend on rotor resistance, yet the speed at which maximum torque is produced depends on rotor resistance c. The maximum torque will not depend on standstill rotor reactance d. The slip of induction motor decreases as torque increases The crawling in the induction motor is caused by a. Improper design of stator laminations b. Low voltage supply c. High loads d. Harmonics developed in motor The rotor slots are slightly skewed in squirrel-cage induction motor to a. Increase the strengths of rotor bars b. Reduce the magnetic hum and locking tendency of rotor c. Economise on the copper to be used d. Provide ease of fabrication The injected e.m.f. in the rotor of induction motor must have a. The same frequency as the slip frequency b. The same phase as the rotor e.m.f.

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3 of 15 c. A high value for satisfactory speed control d. The same phase as the rotor e.m.f. and a high value for satisfactory speed control In an induction motor, when the number of stator slots is equal to an integral multiple of rotor slots a. There may be a discontinuity in torque-slip characteristics b. A high starting torque will be available c. The maximum torque will be high d. The machine may fail to start The use of higher flux density in the transformer design a. Reduces the weight per kVA b. Increases the weight per kVA c. Has no relation with the weight of transformer d. Increases the weight per kW The function of oil in a transformer is to provide a. Insulation and cooling b. Protection against lightning c. Protection against short circuit d. Lubrication A coil of 1000 turns is wound on a core. A current of 1 A flowing through the coil creates a core fluex of 1 mWb. The energy stored in the magnetic field is a. 0.25 J b. 0.5 J c. 1 J d. 2 J Consider the following statements relating to the constructional features of a large power transformer: 1. The conservator is used to maintain the level of oil in the transformer tank 2. The bushing is used to protect transformer insulation against lightning over-voltages 3. The Buchholz relay is an over current relay 4. Silica gel is used to absorb moisture. Which of these statements are correct ? a. 1, 2, 3 and 4 b. 2 and 3 c. 1 and 4

4 of 15 25.

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d. 1, 2 and 4 Two transformers operating in parallel will share the load depending upon their a. Ratings b. Leakage reactance c. Efficiency d. Per unit impedance A 1 kVa, 200/100 V, 50 Hz, single-phase transformer gave the following test results on 50 Hz : OC (LV side) : 100 V, 20 watts SC (HV side) : 5 A, 25 watts It is assumed that no-load loss components are equally divided. The above tests were then conducted on the same transformer at 40 Hz. Tests results were : OC (HV) :160 V, W1 watts. SC (LV) : 10 A, W2 watts Neglecting skin effect, W1 and W2 will be a. W1 = 16 watts, W2 = 25 watts b. W1 = 25 watts, W2 = 31.25 watts c. W1 = 20 watts, W2 = 20 watts d. W1 = 14.4 watts, W2 = 25 watts A generated station has a maximum demand of 30 MW, a load factor of 60% and a plant capacity factor of 50%. The reserve capacity of the plant is a. 5 MW b. 4 MW c. 6 MW d. 10 MW When a ‘pumped storage’ power plant is operated in conjunction with a steam power plant a. The operating cost of the steam plant becomes optimum b. Load factor .of the steam plant is increased c. Chances of the tripping of the system decrease because of the use of two heterogeneous types of plants d. Operation of the storage plant in the puming-mode during the low-load period improves the steam-plant stability Match List I with List II and select the correct answer : List I (Components)

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A. Moderator B. Control Rod C. Coolant D. Shield List II (Materials) 1. Boron 2. Concrete 3. Graphite 4. Sodium A B a. 3 1 b. 1 3 c. 3 1 d. 1 3 The bus admittance system is given as

C D 4 2 2 4 2 4 4 2 matrix of a power

The impedance of line between bus 2 and 3 will be equal to a. + j 0.1 b. – j 0.1 c. + j 0.2 d. – j 0.2 Th.e component inductance due to the internal flux-linkage of a non-magnetic straight solid circular conductor per metre length has a constant value, and is independent of the conductor-diameter, because a. All the internal flux due to a current remains concentrated on the peripheral region of the conductor b. The internal magnetic flux-density along the radial distance from the centre of the conductor increases proportionately to the current enclosed c. The entire current is assumed to flow along the conductor-axis and the internal flux is distributed uniformly and concentrically d. The current in the conductor is assumed to be uniformly distributed throughout the conductor cross-section Match List I with List II and select the correct answer: List I

33.

A. Graetz Bridge Converter B. Series Compensation C. Sag Templates D. Grading Ring List II 1. EHV/UHV AC Transmission 2. HVDC Transmission 3. Insulators 4. Tower Location A B C D a. 2 1 3 4 b. 1 2 4 3 c. 2 1 4 3 d. 1 2 3 4 A 100 km long transmission line is loaded at 110 kV. If the loss of line is 15 MW and the load is 150 MVA, the resistance of the line is a. 8.06 ohms per phase b. 0.806 ohm per phase c. 0.0806 ohm per phase d. 80.6 ohms per phase

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The above circuit shows a 3-phase system having a balanced self-inductive reactance of XL per phase a mutual reactance of Xm between pairs of phases. The line currents are Ia, Ib and Ic, and they may be unbalanced. The series voltage-drop relations would be Vaa’ = Ia XL + Ib Xm + Ic Xm Vbb’ = Ia Xm + Ib XL + Ic Xm Vcc’ = Ia Xm + Ib Xm + Ic XL The positive, negative and zero-sequence reactances X1, X2 and X0, respectively, would be a. (XL – Xm), (XL – Xm) and (XL – 2 Xm) b. (XL + Xm), (XL – 2Xm) and (XL + 2Xm) c. (XL – 2Xm), (XL + Xm) and (XL + Xm) d. (XL + 2Xm), (XL + 2Xm) and (XL + Xm) A rectangular voltage wave is impressed on a loss-free overhead line, with the far

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5 of 15 end of the line being short-circuited. On reaching the end of this line a. The current wave is reflected back with positive sign, but the voltage wave with negative, sign b. The current wave is reflected back with negative sign, but the voltage wave with positive .sign c. Both the current and the voltage waves are reflected with positive sign d. Both the current and the voltage waves are reflected with negative sign Two insulator discs of identical capacitance value C make up a string for a 22 kV, 50 Hz, single-phase overhead line insulation system. If the pin to earth capacitance is also C, then the string efficiency is a. 50% b. 75% c. 90% d. 86% Which one of the following statements is not correct for the use of bundled conductors in transmission lines ? a. Control of voltage gradient b. Reduction in corona loss c. Reduction in radio interference d. Increase in interference with communication lines A power system consists of two areas connected via a tie line. While enter in the data for load flow the tie line parameters and its connectivity data were inadvertently left out, if the load flow program is run with this incomplete data, then the load flow calculations will converge only if a. One slack bus is specified in the first area b. One slack bus is specified in the second area c. One slack bus is specified in either of the two areas d. TWO slack buses, one in each area, are specified

In the network as shown above, the marked parameters are p.u. impedances. The bus-admittance matrix of the network is ⎡10 −5⎤ a. ⎢ ⎥ ⎣ −5 5 ⎦

40.

⎡ 5 −5⎤ b. ⎢ ⎥ ⎣ −5 10 ⎦ ⎡ −10 5 ⎤ c. ⎢ ⎥ ⎣ 5 −5⎦ ⎡ −5 5 ⎤ d. ⎢ ⎥ ⎣ 5 −10 ⎦ Consider the following statements with reference to protective relays 1. The minimum relay coil current at which the relay operates is called pickup value. 2. The pick-up value of a relay is 7.5 A and fault current is 30 A. Therefore, its plug setting multiplier is 5. 3. An earth fault current is generally lesser than the short-circuit current. 4. Induction relays are used with both a.c. and d.c. quantities. Which of these statements are correct ? a. 1 and 2 b. 2 and 3 c. 1 and 3 d. 1, 2 and 4

41.

Four identical 100 MVA, 33 kV generators are operating in parallel, as shown above, in two bus-bar sections, interconnected through a current limiting reactor of x p.u. reactance on the

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6 of 15 generator-base. Each generator has a reactance of 0.2 p.u. The value of the reactor x to limit a symmetrical short-circuit (a-b-c) current through the circuit breaker to 1500 MVA is a. 0.05 p.u. b. 0.10 p.u. c. 0.15 p.u. d. 0.20 p.u. The zero sequence current of a generator for line to ground fault is j 2.4 p.u. Then the current through the neutral during the fault is a. j 2.4 p.u. b. j 0.8 p.u,. c. j 7.2 p.u. d. j 0.24 p.u. In HVDC transmission there are predominant a. Voltage harmonics on d.c. side and current harmonics a.c. side of converters b. Current harmonics on d.c. side and voltage harmonics on a.c. side of converters c. Current harmonics only on the d.c. side of converters d. Voltage harmonics only on the a.c. side of converters Match List I (Different Configurations for Asynchronous Interconnection) with List II (Corresponding Figures) and select the correct answer : List I A. Two-terminal DC Link B. Back to back HVDC Link along with AC feeder C. Back to back HVDC Link at border List II 1.

2.

3.

7 of 15

a. b. c. d.

A 3 2 3 2

B 2 3 1 1

C 1 1 2 3 Consider a silicon transistor connected as a common emitter amplifier as shown above. The quiescent collector voltage of the circuit is approximately a. 6.67 b. 10 V c. 14 d. 20 V

45.

46.

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Consider a power system with two plants S1 and S2 connected through a tie line as shown above. When the load-frequency control of the system is considered, the ‘Flat tie-line control’ system is preferred over the ‘Flat frequency regulation system’, because a. It is advantageous to control the frequency from any one particular plant without disturbing the other one during load-swings on either S1 or S2 areas b. This ensures that only the more efficient plant’s input is controlled for load, variation in any area c. Only the tie line is required to absorb the load-swing d. The load-change in a particular area is taken care of by the generator in that area resulting in the tie-line loading to remain constant In a p-n junction, to make the depletion region extent predominantly into p-region, the concentration of impurities in the pregion must be a. Much less than the concentration of impurities in n-region b. Much higher than the concentration of impurities in n-region c. Equal to the concentration of impurities in n-region d. Zero

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In the transistor circuit as shown above, the collector to ground voltage is + 20 V. The possible condition is a. Collector-emitter terminals shorted b. Emitter to ground connection open c. 10 kilo-ohms resistor open d. Collector-base terminals shorted In an RC coupled common emitter amplifier a. Coupling capacitance affects the h.f. response, and bypass capacitance affects the 1.f response b. Both coupling and bypass capacitances affect the h.f. response c. Both coupling and bypass capacitances affect the 1.f. response only d. Coupling capacitance affects the 1.f. response and the bypass. capacitance affects the h.f. response Consider the following with reference to a CE transistor amplifier: 1. The use of negative feedback 2. The conversion of d.c. power to a.c. 3. High voltage and current gains 4. The use of a step-up transformer The power gain is due to

8 of 15

51.

a. 1 and 2 b. 2 and 3 c. 1 and 3 d. 1 and 4 The open-loop voltage gain of an amplifier is 240. The noise level in the output without feedback is 100 mV. If a negative feedback with β = 1/60 is used, the noise level in the output will be a. 1.66 mV b. 2.4 mV c. 4.0 mV d. 20 mV

b. 1 c. 3 d. 29 55.

Consider the following statements with reference to an ideal voltage follower circuit as shown above : 1. Unity gain and no phase shift 2. Infinite gain and 1800 phase shift 3. Very high input impedance and very low output impedance 4. It is a buffer amplifier Which’ of these statements are correct ? a. 1 and 3 b. 2 and 4 c. 1, 3 and 4 d. 1, 2, 3 and 4

52.

53.

In the circuit as shown above, the ratio of V0 to (V2–V1) would approximately (neglecting constant due to Vcc) be a. RC / RE b. RE / RC c. –RC / RE d. –RE / RC An op-amp has a differential gain of 103 and a CMRR of 100. The output voltage of the op-amp with inputs of 120 μV and 80μV will be a. 26 mV b. 41 mV c. 100 mV d. 200 mV

54.

An FET oscillator uses the given phase shift network as shown above. The minimum gain required for oscillation is a. –29

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In the op-amp circuit as shown above, the current iL is a. Vi / ZL b. Vi / ZL | | R1 c. Vi / R1 d. Vi(R1 + ZL) Match List I (Circuits) with List II (Characteristics/Applications) and select the correct answer : List I A. High-pass RC circuit B. Low-pass RC circuit C. Clamping circuit D. Clipping circuit List II 1. Comparator 2. DC Restorer

9 of 15

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3. Integrator 4. Differentiator 5. Compensated Attenuator A B C D 5 4 2 1 a. 4 3 1 2 b. 5 4 1 2 c. 4 3 2 1 d. The simplified form of a logic function Y

(

)(

)

= A B . A B is

a. A + B b. A B

63.

c. A + B 59.

d. A B + A B The reduced form of the Boolean expression A[B + C( AB + AC )] is a. AB

The above shown NMOS circuit is a gate of the type a. NAND b. NOR c. AND d. EXCLUSIVE-OR D flip-flop can be made from a J-K flipflop by making a. J = K b. J = K = 1 c. J = 0, K = 1 d. J = K

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b. AB c. AB

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d. AB + BC An n-bit AID converter is required to convert analog input in the range 0-5 V to an accuracy of 10 mV. The value of n should be a. 16 b. 10 c. 9 d. 8 Consider the following statements in respect of ECL gate: 1. Its switching speed is high 2. It provides OR and NOR logic operations 3. Its power dissipation is small as compared to other logic gates 4. Its logic levels are compatible with other logic family gates Which of these statements are correct ? a. 1 and 2 b. 1, 2 and 3 c. 1, 2 and 4 d. 3 and 4

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66.

In the circuit as shown above, assuming initially Q0 = Q1 = 0. Then the states of Q0 and Q1 immediately after the 33rd pulse are a. 1 1 b. 1 0 c. 0 1 d. 0 0 Which one of the following statements is not correct? Conversion of EXCESS-3 code to BCD can be achieved by using a. Discrete gates b. 4 : 16 de-multiplexer c. 4-bit full adder d. A 4-bit half adder

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The three-stage Johnson Ring Counter as shown above is clocked at a constant frequency of fc from the starting state of Q0 Q1 Q2 = 101. The frequency of outputs Q0 Q1 Q2 will be a. fc / 8 b. fc / 6 c. fc / 3 d. fc / 2 A 4-bit modulo-16 ripple counter uses J-K flip-flop. If the propagation delay of each flip-flop is 50 nanoseconds, the maximum clock frequency that can be used is equal to a. 20 MHz b. 10 MHz c. 8 MHz d. 5 MHz The binary representation 100110 is numerically equivalent to the 1. Decimal representation 46 2. Octal representation 46 3. Hexadecimal representation 26 4. Excess-3 representation 13 Select the correct answer using the codes given below : a. 1 and 2 b. 2 and 3 c. 1 and 3 d. 2 and 4 A Direct Memory Access (DMA) transfer implies a. Direct transfer of data between memory and accumulator b. Direct transfer of data between memory and I/O devices without the use of microprocessor c. Transfer of data exclusively with in microprocessor registers d. A fast transfer of data between microprocessor and I/O devices After an arithmetic operation, the flag register of a 8085 microprocessor has the following look:

The arithmetic operation has resulted in

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73.

74.

10 of 15 a. A carry and an odd parity number having 1 as the MSB b. Zero and the auxiliary carry flag being set c. A number with even parity and I as the MSB d. A number with odd parity and 9 as the MSB The program counter in a 8085 microprocessor is a 16-bit register, because a. It counts 16 bits at time b. There are 16 address times c. It facilitates the user storing 16-bit data temporarily d. It has to fetch two 8-bit data at a time A microprocessor is ALU a. and control unit on a single chip b. and memory on a single chip c. register unit and I/O device on a single chip. d. register unit and control unit on a single chip In Intel 8085 A microprocessor ALE signal is made high to a. Enable the data bus to be used as low order address bus b. To latch data D0 — D7 from data bus c. to disable data bus d. To achieve all the functions listed above Examine the following instruction to be executed By a 8085 microprocessor. The input port has an address of 01 H and has a data 05H to input : IN 01 ANI 80 After execution of the two instructions the following flag portions may occur : 1. Zero flag is set 2. Zero flag is reset 3. Carry flag is cleared 4. Auxiliary carry flag is set Select the correct answer using the codes given below: a. 1 and 3 b. 2, 3 and 4 c. 3 and 4

75.

76.

77.

78.

d. 1, 2 and 4 Match List I (Introduction) with List Il (Type of Addressing) and select the correct answer : List I A. MOVA,M B. LXIH, E400H C. LDA Fl CDH D. CMC List II 1. Direct addressing 2. Register addressing 3. Implicit addressing 4. Register indirect addressing 5. Immediate addressing A B C D 5 4 1 3 a. 4 5 3 1 b. 5 4 2 3 c. 4 5 1 3 d. How many and which types of machine cycles are needed to execute PUSH PSW by an Intel 8085A microprocessor? a. 2, Fetch and Memory write b. 3, Fetch and 2 Memory write c. 3, Fetch and 2 Memory read d. 3, Fetch, Memory read and Memory write Output of the assembler in machine codes is referred to as a. Object program b. Source program c. Macroinstruction d. Symbolic addressing Three devices A, B and C are connected to an Intel 8085 A microprocessor. Device A has the highest priority and device C has the lowest priority. The correct assignment of interrupt inputs is a. A uses RST 5.5, B uses RST 6.5 and C uses TRAP b. A uses RST 5.5 B uses RST 6.5 and C uses RST 7.5 c. A uses RST 7.5, uses RST 6.5 and C uses RST 5.5 d. A uses TRAP, B uses RST 5.5 and C uses RST 6.5

79.

80.

81.

82.

83.

84.

11 of 15 If the accumulator of n Intel 8085 A microprocessor contains 37 H and the previous operation has set the carry flag, the instruction ACl 56 H will result in a. 8 E H b. 94 H c. 7 E H d. 84 H Which one of the following statements about RAM is not correct? a. RAM stands for random-access memory b. It is also called read/write memory c. When power supply is switched off, the information in RAM is usually lost d. The binary contents are entered or stored in the RAM chip during the manufacturing state A handshake signal in a data transfer is transmitted a. Along with the data bits b. Before the data transfer c. After the data transfer d. Either along with the bits or after the data transfer Which one of the following is not a vectored interrupt ? a. TRAP b. INTR c. RST 3 d. RST 7.5 Ports are used to connect the CPU to which of the following units? 1. Printer 2. Floppy disk drives 3. Video display unit 4. Incoming power supply Select the correct answer using the codes given below : a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 1 and 3 For an AM signal, the bandwidth is 10 kHz and the highest frequency component present is 705 kHz. The carrier frequency used for this AM signal is a. 695 kHz

85.

86.

87.

88.

89.

b. 700 kHz c. 705 kHz d. 710 kHz If large amount of information is to be transmitted in a small amount of time, we require a. Low-frequency signals b. Narrow-band signals c. Wide-band signals d. High-frequency signals Match List I (System) with List II (Application) and select the correct answer: List I A. Pre-emphasis B. Armstrong Method C. Envelope Detector D. De-Emphasis List II 1. AM Detector 2. FM Receiver 3. FM Generator 4. FM Transmitter 5. AM Transmitter A B C D 4 3 2 1 a. 3 5 1 2 b. 4 3 1 2 c. 5 3 2 1 d. A modulator is a device to a. Separate two frequencies b. Impress the information on to a radio frequency carrier c. Extract information from the carrier d. Amplify the audio frequency signal A modulation technique in which bandwidth of the modulated signal is extended well beyond the bandwidth of the modulating signal, independent of the modulating. signal bandwidth, is called a. Wide-band modulation b. Extended bandwidth modulation c. Spread spectrum modulation d. Narrow-band modulation In AM, the percentage of total power in sideband is a. 10%

90.

91.

92.

93.

94.

95.

12 of 15 b. 16.67% c. 23.34% d. 37.5% Which of the following desirable features are possessed by SSB in comparison to AM ? 1. Less power is required 2. Bandwidth required is less 3. Antenna size can be reduced 4. Lower frequency can be used Select the correct answer using the codes given below : a. 3 and 4 b. 2, 3 and 4 c. 1 and 2 d. 1, 2 and 4 The detection-gain for coherent DSB demodulator is a. 2 b. 4 c. 8 d. 16 Power spectral density of a signal is a. Complex, even and non-negative b. Real, even and non-negative c. Real, even and negative d. Complex, odd and negative Which one of the following multiplexing techniques involves signals composed of light beams ? a. CDM b. FDM c. TDM d. WDM In a communication system, a process for which statistical averages and timeaverages are equal, is called a. Stationary b. Ergodic c. Gaussian d. BIBO stable In which type of the switchings given below, entire capacity of a dedicated link is used ? a. Circuit switching b. Data gram packet switching c. Virtual circuit packed switching

96.

97.

98.

99.

d. Message switching In TV transmission, the modulation schemes for Video and Audio are, respectively a. FM and AM b. FM and FM c. AM and FM d. AM and AM Match List I (Converters) with List II (Type of Conversion) and select the correct answer : List I A. Controlled Rectifier B. Chopper C. Inverter D. Cycloconverter List II 1. Fixed DC to variable voltage and variable frequency AC 2. Fixed DC to variable DC 3. Fixed AC to variable DC 4. Fixed AC to variable frequency AC A B C D 2 3 1 4 a. 3 2 4 1 b. 2 3 4 1 c. 3 2 1 4 d. Turn-on and turn-off times of transistor depend on a. Static characteristic b. Junction capacitances c. Current gain d. None of the above Match List I (Characteristic/Action) with List II (Observations) and select the correct answer: List I A. Turn-on time of thyristor B. Turn-on time of transistor C. Rate of rise of gate current in thyristor D. If the gate pulse is removed, when the thyristor is carrying a current, less than latching current List II 1. Depends on junction capacitances 2. Is the sum of delay and rise times 3. Thyristor switches back to OFF-state

100.

101.

102.

13 of 15 4. Affect the delay time A B C D 2 1 4 3 a. 1 2 3 4 b. 2 1 3 4 c. 1 2 4 3 d. An ideal chopper operating at a frequency of 500 Hz, supplies a load having resistance of 3 ohms and inductance of 9 mH from a 60 V battery. The mean value of the load voltage for on/off ratio of 4/1, (assuming that load is shunted by a perfect commutating diode and battery is lossless) is a. 240 V b. 48 V c. 15V d. 4V The characteristic features of discontinuous conduction compared to continuous conduction in a four-pulse, single-phase bridge converter are a. Larger average value of load voltage and larger ripple-content b. Larger average value of load voltage and smaller ripple-content c. Smaller average value of load voltage and smaller ripple content d. Smaller average value of load voltage and larger ripple-content If the r.m.s. source voltage is V volts, the minimum and maximum values of firing angles for a single-phase, half-wave controlled rectifier, supplying a load with a back e.m.f. of 40 volts are a. 00 and 180o b. α = sin–1 (40/

2V ) and 1800

c. α = sin–1 (40/ (40/ 2V )] 103.

2V ) and [π–sin–1

d. 00 and [π – sin–1 (40/ 2V )] An AC voltage-regulator using back-toback connected SCRs is feeding an RL load. The SCR firing angle α < φ (φ is power factor angle of the load). If SCRs are fired using short-duration gate pulses, the output load-voltage waveform will be a. Symmetrical chopped ac. voltage b. Half-wave rectified

104.

105.

c. Full-wave rectified d. Sinusoidal In a self-controlled synchronous motor fed from a variable frequency inverter a. The rotor poles invariably have damper windings b. There are stability problems c. The speed of the rotor decides stator frequency d. The frequency of the stator decides the rotor speed A d.c. source is switched in steps to synthesize the three-phase output. The basic three-phase bridge inverter can be controlled. The angle through which each switch conducts, and at any instant the number of switches conducting simultaneously are, respectively. a. 120° and 02 b. 120° and 03 c. 180° and 02 d. 1800 and 04

108.

109.

110.

106.

111.

107.

For a single-phase, full-bridge inverter supplying power to a highly inductive load as shown above, the correct sequence of operation of switches and diodes is a. S1S4 – S3S2 – S1S4 – S3S2 b. D1D4 – S1S4 – D2D3 – S2S3 c. S1D3 – S1S4 – S4D2 – D2D3 d. S2D4 – D4D1 – D1S3 – S3S2 A single-phase, half-bridge inverter has input voltage of 48 V DC. Inverter is feeding a load of 2.4 Ω. The r.m.s. output voltage at fundamental frequency is 2 × 48V a.

π

2 × 48V b. 2π c.

2 × 48V

π

112.

14 of 15 2 × 48V d. 2 2π A boost-regulator has an input voltage of 5V and the average output voltage of 15 V. The duty cycle is a. 3/2 b. 2/3 c. 5/2 d. 15/2 An inter-group reactor is used in a singlephase cycloconverter circuit to a. Reduce current-ripples b. Reduce voltage-ripples c. Limit circulating current d. Limit di/dt in the semiconductor switch Assertion (A) : DC series motors are suitable for cranes. Reason (R) : DC, series motors provide high starting torque. a. Both A and R are individually true and R is the correct explanation. of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The short circuit, ratio (SCR) of a three-phase alternator should be high. Reason (R) : A high value of SCR will decrease the value of voltage regulation and will increase the maximum power output. a. Both A and R are individually true and R is the correct explanation. of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Single-phase induction motor is not self-starting. Reason (R) : No rotating magnetic field is set up in the air gap of a single-phase induction motor. a. Both A and R are individually true and R is the correct explanation. of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true

113.

114.

115.

116.

117.

Assertion (A) : A double-cage induction motor has good starting characteristics. Reason (R) : At starting, a large position of starting current flows in the bottom cage. a. Both A and R are individually true and R is the correct explanation of A. b. Both A and R are individually true but R is not the correct explanation of A. c. A is true but R is false d. A is false but R is true Assertion (A) : Hydroelectric plants with large storage can be best used as base toad plants high load factor. Reason (R) : For a plant to .be used as base plant, the unit cost of energy generated by the plant should be low. a. Both A and R are individually true and R is the correct explanation. of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Transistor h-parameter equivalent circuit can be used for the analysis irrespective of the configuration (CE, CB or CC) of the transistor used. Reason(R) : The values of h-parameter remain unchanged with transistor configuration. a. Both A and R are individually true and R is the correct explanation. of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : In an asynchronous counter, output of each FF serves as CLK input signal for the next FF Reason (R) : All the FFs do not change states in exact synchronism with the clock pulses. a. Both A and R are individually true and R is the correct explanation. of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) :. The zero-flag of a 8085 microprocessor is not affected after the

118.

119.

120.

15 of 15 execution of the following couple of instructions MVI B, 03 MOV A, B Reason (R) : After the execution of a data transfer instruction, zero-flag is set if the accumulator content is zero. a. Both A and R are individually true and R is the correct explanation. of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Microwave links are generally preferred to coaxial cable for TV transmission. Reason (R) : Microwave links have greater bandwidth than coaxial cables. . a. Both A and R are individually true and R is the correct explanation. of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : FM transmission is noise free. Reason (R) : In FM, information is carried as frequency variation. a. Both A and R are individually true and R is the correct explanation. of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : The critical rate of change of forward-voltage is the value of dv/dt, at which the device just goes into conduction without a gate pulse. Reason (R) : Thyristors go to a state of conduction with the application of sharp rate of change of forward-voltage in the absence of gate pulse, even before the break- forward voltage limit is reached. a. Both A and R are individually true and R is the correct explanation. of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true

I.E.S-(OBJ) 2004

1 of 16

ELECTRICAL ENGINEERING PAPER-II 1.

The diagram given below shows the connection of a four–wire delta bank for obtaining a 3–phase 4–wire distribution system. The secondary voltages between the terminals are as indicated, a

4.

What is the voltage between the terminals b and d in the above system when the primary side is energized from an appropriate symmetrical 3–phase system? a. 230 /

2 V

b. 230 /

3 V

c. 115 × 3 V 2.

3.

d. 115 × 2 V If per unit impedances of two transformers connected in parallel are not equal, then which one of the following statements is correct? a. The power factor of the two transformers will be different from that of the connected load b. Transformers will get overloaded c. Dead short circuit occurs d. The transformer with higher per unit impedance will share more load Match List I (Machine) with List II (Performance) and select the correct answer using the codes given below : List I A. Three phase induction motor B. Synchronous motor C. D. C. series motor D. D. C. shunt motor List II 1. Adjustable speed 2. High starting torque 3. Not self–starting

5.

6.

4. Self–starting A B C D 3 4 1 2 a. b. 4 3 1 2 3 4 2 1 c. d. 4 3 2 1 In a d.c. machine, for the same values of φ, Z and N; which one of the following statements is correct ? a. Armature e.m.f. is more with wave winding than with lap winding b. Armature e.m.f. is less with wave winding than with lap winding c. Armature e.m.f. depends on whether the machine is running as a motor or a generator d. Armature e.m.f. is the same as long as the flux density in the air gap remains the same Match List I (Constructional Components) with List II (Machines) and select the correct answer using the codes given below : List I A. Damper bars B. Equalizer rings C. Skewed slots D. Water–cooling ducts List II 1. Cylindrical – rotor synchronous generator 2. Salient pole synchronous motor 3. Squirrel–cage induction motor 4. Direct current generator A B C D 2 4 3 1 a. 1 3 4 2 b. 1 4 3 2 c. d. 2 3 4 1 A d.c. shunt motor is excited from an alternating power frequency voltage

7.

8.

source. Its brush–axis is rotated by an. angle α from the geometrical neutral axis. The torque developed will be proportional to which one of the following? a. sin α b. cos α c. tan α d. cos 2α Four types of d.c. generators of constant speed are considered (List I). Their external characteristics at constant speed are given in List II. Match List I (Type of d.c. generator) with List II (External characteristics) and select the correct answer using the codes given below : List I (Type of d.c. generator) A. Separately excited B. Series excited C. Shunt excited D. Over–compound excited List II (External characteristics) 1.

A B C D a. 2 3 1 4 1 4 2 3 b. c. 1 3 2 4 2 4 1 3 d. Consider the following statements: The speed of a d.c. motor can be controlled by the variation of 1. armature voltage 2. field current 3. armature circuit resistance 4. angle of brush shift Which of the statements given above are correct ? a. 1, 2 and 3 b. 2, 3 and 4 c. 1, 3 and 4 d. 1, 2 and 4

9.

10.

11.

2 of 16 What is the increase in the torque expressed as percentage of initial torque, if the current drawn by a d.c. motor is increased from 10 A to 12 A (Neglect saturation)? a. 21% b. 25% c. 41% d. 44% Consider the following statements In a d.c. machine, iron loss occurs in 1. armature core 2. yoke 3. pole cores 4. pole shoes Which of the statements given above are correct? a. 1 and 4 b. 1 and 2 c. 1 and 3 d. 2 and 3 Four important parameters of alternators have comparatively larger or smaller values. In comparison to a steam turbine driven alternator, a hydraulically driven machine will have which one of the following combinations? Number of armature conductors

12.

13.

Axial length of armature conductors

Number of poles

Operating speed

a. Smaller larger smaller higher b. Larger smaller larger lower larger smaller lower c. Larger higher d. Smaller smaller larger Which one of the following is the primary reason for placing field on rotor in an alternator? a. Small power .in field circuit b. Insulation of high voltage is made easy on stator than on rotor c. Large power in stator d. Large current in the stator Consider the following: 1. Supply voltage 2. Excitation current 3. Maximum value of load angle

14.

15.

16.

17.

18.

The maximum power developed by a synchronous motor is a function of which of the above? a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2 and 3 When a 3–phase alternator is suddenly short–circuited at its terminals, the initial value of the short–circuit current is limited by which one of the following ? a. Subtransient reactance x”d b. Transient reactance x’d c. Synchronous reactance xs d. Sum of x”d, x’d and xs Which one of the following methods gives more accurate result for determination of voltage regulation of an alternator? a. m.m.f. method b. Synchronous impedance method c. Potier triangle method d. American Institution Standard method Which one of the following statements is correct? In a salient pole synchronous machine the air gap is a. uniform under the whole pole shoe b. least under the middle of the pole shoe and increases outwards c. largest under the middle of the pole shoe and decreases outwards d. least at one end of the pole shoe and increases to the maximum Value at the other end Which one of the following is not a necessary condition to be satisfied for synchronising an incoming alternator to an already operating alternator? a. Same voltage magnitude b. Same frequency c. Same prime mover speed d. Same phase sequence Which one of the following statements is correct? A smaller air gap in a polyphase induction motor helps to a. reduce the chances of crawling b. increase the starting torque

19.

20.

21.

22.

23.

3 of 16 c. reduce the chance of cogging d. reduce the magnetizing current Which one of the following statements is correct? In an induction motor, if the air gap is increased, a. its speed will reduce b. its efficiency will improve c. its power factor will reduce its breakdown torque will reduce Which one of the following statements is correct? In a 3–phase induction motor, the torque developed is maximum when the rotor circuit resistance per phase is equal to a. rotor leakage reactance per phase at standstill b. slip times the rotor leakage reactance per phase at standstill c. stator resistance per phase d. stator leakage reactance per phase The supply voltage to an induction motor is reduced by 10%. By what percentage, approximately, will the maximum torque decrease? a. 5% b. 10% c. 20% d. 40% Consider the following curve

Which of the following characteristics of the induction represented by the above curve? x—axis y—axis p.f. a. Output p.f. b. Speed c. Load efficiency torque d. Speed A squirrel–cage induction motor having a rated slip of 4% on full load has a starting torque same as the full load torque. Which one of the following statements is correct?

24.

25.

26.

27.

The starting current is a. equal to the full load current b. twice the full load current c. four times the full load current d. five times the full load current Which one of the following types of motors is most suitable for a computer printer drive? a. Reluctance motor b. Hysteresis motor c. Shaded pole motor d. Stepper motor For a reluctance type motor, if the stator magnetic field angular velocity is ω and the actual rotor angular velocity is ωr, and then which one of the following equations is satisfied if the average electromagnetic torque is not zero ? a. ω = ωr / 2 b. ω = ωr c. ω = 2ωr d. ω = 4ωr Which one of the following statements is correct? When a single phase induction motor is excited with single phase a.c. voltage, the magnetic field set up is equivalent to a. two fields, rotating in opposite directions with different speeds b. two fields, rotating at synchronous speed in opposite directions c. two fields, rotating at synchronous speed d. two fields rotating in the same direction but at different speeds Consider the following statements regarding pumped storage plants : 1. A pumped storage plant is a base load plant. 2. The starting time of a pumped storage plant is very short 3. Reversible turbines and pumps are highly suitable for pumped storage plants Which of the statements given above are correct? a. 1 and 2 b. 1 and 3

28.

29.

30.

4 of 16 c. 2 and 3 d. 1, 2 and 3 Which one of the following equations is correct? a. –AB + CD = –1 b. AD + CB = 1 c. AB – CD = –1 d. –AD + BC = –1 where A, B,C and D are generalized circuit constants. Match List I (Name of Power Plant) with List II (Plant Features) and select the correct answer using the codes given below: List I A. Thermal B. Nuclear C. Hydro D. Diesel List II 1. High operating cost 2. High capital cost 3. High plant life 4. High fuel transportation cost A B C D 3 1 4 2 a. 4 2 3 1 b. c. 3 2 4 1 4 1 3 2 d. The combined effect of series and shunt compensation on transmission lines in terms of degree of series compensation (Kse), degree of shunt compensation (Ksh), and surge impedance of uncompensated line (Z0) is given by which one of the following equations ? a. Z 0' = Z 0 1 − K se . 1 − K sh b. Z 0' = ⎡⎣ 1 − K se . 1 − K sh ⎤⎦ / Z 0

31.

c. Z 0' = Z 0

(1 − K se ) / (1 − K sh )

d. Z 0' = Z 0

(1 − K sh ) / (1 − K se )

Match List I (Classification based on Head) with List II (Type of Turbine) and select the correct answer using the codes given below : List I

32.

33.

34.

35.

A. Low head, 2–15 m B. Medium head, 16–70 m C. High head, 71–500 m D. Very high head, > 500 m List II 1. Pelton 2. Francis or Pelton 3. Kaplan or Francis 4. Propeller or Kaplan A B C D a. 4 3 2 1 3 4 1 2 b. c. 4 3 1 2 d. 3 4 2 1 Ds is the GMR of each subconductor of a four subconductor bundle conductor and d is the bundle spacing. What is the GMR of equivalent single conductor? a. 1.09

Ds × d

b. 1.09

Ds 3 × d 3

36.

37.

3

c. 1.09

4

Ds 3 × d 3

d. 1.09

4

Ds × d 3

Which one of the following statements is correct? Corona loss increases with a. decrease in conductor size and increase in supply frequency b. increase in both conductor size and supply frequency c. decrease in both conductor size and supply frequency d. increase in conductor size & decrease in supply frequency For a fixed receiving end and sending end voltage in a transmission system, what is the locus of the constant power? a. A straight line b. An ellipse c. A parabola d. A circle At slack bus, which one of the following combinations of variables is specified ? a. | V |, δ b. P.Q c. P.| V |

38.

39.

5 of 16 d. Q, | V | (The symbols have their usual meaning) Consider the following quantities : 1. Real power 2. Reactive power 3. Power factor 4. Input current 5. Bus voltage magnitude 6. Bus voltage phase–angle For the purpose of the load f1ow studies of a power system, each bus or node is associated with which one of the combinations of the above four quantities? a. 1, 3, 4 and 5 b. 1, 2, 3 and 4 c. 2, 3, 5 and 6 d. 1, 2, 5 and 6 Consider the following statements regarding load frequency control : 1. Time constant of automatic load frequency control is about 15 seconds. 2. Integral control eliminates static frequency drop. 3. In tie-line load bias control, the control signal for each area is proportional to change in frequency as well as change in tie-line power. Which of the statements given above are correct? a. 1, 2 and 3 b. 1 and 2 c. 1 and 3 d. 2 and 3 Which one of the following statements i.s correct? Normally ZBUS matrix is a a. Null matrix b. Sparse matrix c. Full matrix d. Unity matrix j

2π

If α = e = e 3 , and I = AIs where I is equal to phase current vector and Is is equal to symmetrical current vector, then which one of the following matrices is the symmetrical components transformation matrix A?

1⎤ ⎡1 1 ⎢ a. ⎢1 α α 2 ⎥⎥ ⎢⎣1 α 2 α ⎥⎦

⎡1 α α 2 ⎤ ⎢ ⎥ b. ⎢1 1 1⎥ ⎢1 α 2 α ⎥ ⎣ ⎦ 1⎤ ⎡1 1 ⎢ 2 c. ⎢1 α α ⎥⎥ ⎢⎣1 α α 2 ⎥⎦

40.

⎡1 α 2 α ⎤ ⎢ ⎥ d. ⎢1 α α 2 ⎥ ⎢1 1 α ⎥ ⎣ ⎦ old Zpu is the per unit impedance on the power base SBold and voltage base VBold what would be the per unit impedance on the new power base SBnew and voltage base VBnew ? a. Zpu

new

= Zpu

old

b. Zpu

new

= Zpu

old

c. Zpu new = Zpu old

⎛ VBnew ⎞ Sold B ⎜ old ⎟ Snew ⎝ VB ⎠ B

2

⎛ VBold ⎞ Snew B ⎜ new ⎟ Sold ⎠ B ⎝ VB

2

Snew B Sold B

43.

⎛ VBold ⎞ ⎜ new ⎟ ⎝ VB ⎠

⎛ VBnew ⎞ Sold B ⎜ old ⎟ Snew B ⎝ VB ⎠ Consider the following statements regarding the fault analysis : 1. The neutral grounding impedance Z appears as 3 Zn, in zero sequence equivalent circuit. 2. For faults on transmission lines, 3phase faults the least severe amongst other faults. 3. The positive and negative sequence networks are not affected by method of neutral grounding. Which of the statements given above are correct? a. 2 and 3 b. 1 and 2 c. 1 and 3 d. 1, 2 and 3 Consider the following statements :

d. Zpu new = Zpu old

41.

42.

44.

6 of 16 Stability studies constitute 1. the major analytical approach V to the study of power system electromechanical dynamic behaviour. 2. the involvement of one or just a few machines undergoing slow or gradual changes in operating conditions. 3. the determination of the locus of essentially steady-state operating points of the system. 4. the determination of whether or not the rotors of the machines being perturbed, return to the constant speed operation. Which of the statements given above are correct? a. 1, 2 and 3 b. 2, 3 and 4 c. 1 and 4 d. 1, 2, 3 and 4 If a sudden short circuit occurs on a power system (considered as RL series circuit), the current wave-form consists of 1. a decaying a.c. current. 2. a decaying d.c. current. Let the alternator reactance be X and the power system resistance R. Which one of the following is correct ? a. The decay in (1) is caused by the increase in X but in (2)is caused by R b. The decay in (1) is caused by R but in (2) is caused by increase in X c. The decay in both (1) and (2) is caused by R d. The decay in both (1) and (2) is caused by the increase in X Match List I (Type of Relays) with List II (Types of Protection) and select the correct answer using the codes given below: List I A. Directional relay B. Impedance relay C. Differential relay D. Pilot relay List II 1. Relay operates for fault within certain distance of its location 2. Relay will trip for fault in one location and block for all other locations

45.

46.

3. High speed protection for entire transmission line 4. The principle of current continuity is used to devise a simple and effective relaying system over a small physical space A B C D 1 2 4 3 a. 2 1 3 4 b. 2 1 4 3 c. d. 1 2 3 4 Consider the following statements regarding the suitable choice of HVDC converter configuration: 1. Pulse number should be high. 2. Ratio of peak inverse voltage to no load d.c. output voltage should be as high as possible. 3. Transformer utilization factor should be nearly unity. Which of the statements given above are correct? a. 1 and 2 b. 1, 2 and 3 c. 2 and 3 d. 1 and 3 Two identical RC coupled amplifiers, each having an upper cut-off frequency fu, are cascaded with negligible loading. What is the upper cut-off frequency of the overall amplifier? fu a. 2 −1 b.

47.

fu

fl

c. fl / 2 d. 2fl

49.

2 −1

7 of 16 A synchronous sequential circuit is designed to detect a bit sequence 0101 (overlapping sequence included). Every time this sequence is detected, the circuit produces an output of ‘1’. What is the minimum number of states the circuit must have ? a. 4 b. 5 c. 6 d. 7 Match List I (Circuit Symbols) with List II (Nomenclature) and select the correct answer using the codes given below : List I A. B.

C.

D.

2 −1

c. fu / 2 d. 2fu Two identical RC coupled amplifiers, each having a lower cut-off frequency fl are cascaded with negligible loading. What is the lower cut-off frequency of the overall amplifier? fl a. 2 −1 b.

48.

50.

List II 1. NAND 2. NOR 3. Buffer 4. Schmitt trigger A B C D a. 4 3 1 2 3 4 2 1 b. 4 3 2 1 c. d. 3 4 1 2 If x and y are Boolean variables, which one of the following is the equivalent of x⊕ y⊕xy ?

a. x + y

51.

b. x + y c. 0 d. 1 Consider the following multivibrator circuit:

bistable

52.

53.

54.

Which one of the following statements is correct ? In the above circuit, condensers C1 and C2 are used a. for passing the noise b. to compensate The collector-emitter capacitance c. to speed up the switching action d. to provide negative feedback path Consider the following statements : 1. TTL has high switching speed and good fan-out capability. 2. ECL has the least propagation delay. 3. I2L uses multi-collector transistors 4. N MOS has more silicon area. Which of the statements given above are correct ? a. 1, 2 and 3 b. 2 and 4 c. 1, 3 and 4 d. 1, 2, 3 and 4 Which one of the following statements is correct? An ideal regulated power supply should have a. 100% regulation b. 50% regulation c. 0% regulation d. 75% regulation Match List I with List II and select the correct answer using the codes given below List I (Operation) A. Counting B. Decoding C. Data selection D. Code conversion List II (Associated Device) 1. ROM 2. Multiplexer

55.

56.

57.

58.

8 of 16 3. Demultiplexer 4. Register A B C D a. 3 4 2 1 3 4 1 2 b. c. 4 3 1 2 d. 4 3 2 1 Which one of the following statements is correct? A photodiode works on the principle of a. photo-voltaic effect b. photo-conductive effect c. photo-electric effect d. photo-thermal effect Match List I with List II and select the correct answer using the codes given below: List I (Circuit) A. Monostable multi vibrator B. Bistable multivibrator C. Clamping circuit D. Schmitt trigger List II (Application) 1. Comparator 2. d.c. level translator 3. Delay. 4. Voltage controlled oscillator 5. Counter A B C D a. 4 3 1 2 b. 3 5 2 1 4 5 2 1 c. d. 5 4 1 2 What are the values respectively, of R1 and R2 in the expression (235)R1 = (565)10 = (865)R2 ? a. 8, 16 b. 16, 8 c. 6, 16 d. 12, 8 Match List I (Sections of a Service Voltage Regulator) with List II (Elements used in these Sections) and select the correct answer using the codes given below: List I

59.

60.

A. Reference source B. Error detector C. Control device D. Current limit List II 1. Op-Amp 2. BJT 3. Zener diode 4. Short circuit protection A B C D a. 3 1 2 4 3 2 1 4 b. c. 4 2 1 3 d. 4 1 2 3 Which. one of the following statements is correct? The efficiency of class B push-pull amplifiers is much higher than that of class A amplifiers primarily because a. the distortion is kept within acceptable limits b. one half of the input signal ,is amplified using one transistor and the other half is phase-inverted and fed to the other transistor c. matched pair transistors are used in push-pull operation d. the, quiescent d.c. current is avoided the class B Consider the following circuit:

61.

62.

63.

9 of 16 It is required to construct a 2n-to-l multiplexer by using 2-to-1 multiplexers only. How many of 2-to-1 multiplexers are needed? a. n b. 22n c. 2n–1 d. 2n – 1 A inverter gate has guaranteed output levels as: logic ‘1’ = 3.8 V and logic ‘0’ = 0.7 V. The maximum low level input voltage at which the output remains high 2 V. The minimum high-level input voltage at which the output remains low = 3.1 V. What are the noise margins of this gate ? a. NMH = 2.4 V, NML = 1.8 V b. NMH = 1.8 V, NML = 1.3 V c. NMH = 0.7 V, NML = 1.8 V d. NMH = 0.7 V, NML = 1.3 V Consider the following circuit :

Which one of the following gives the function implemented by the MUX-based digital circuit ?

(

a. f = C2. C1 . S + C 2 . C1 . A + B

)

b. f = C 2 . C1 .C2.C1+C2. C1 .S+ C 2 .C1. Ab c. f = AB + S d. f = C 2 . C1 + C2. C1 . S + C 2 .C1. AB 64. Which one of the following is the correct expression for the Current I0 ? Vs .RL a. Rs ( RL + Rs )

b.

Vs Rs

c.

Vs RL

⎛ 1 1 ⎞ d. Vs ⎜ + ⎟ ⎝ RL Rs ⎠

65.

Which one of the following statements is correct? For a 4-input NOR gate, when only two inputs are to be used, the best option for the unused inputs is to a. connect them to the ground b. connect them to VCC c. keep them open d. connect them to the used inputs A range decoder is a ‘digital circuit which outputs a ‘1’ whenever an m-bit number X falls within the range, 2p ≤ X ≤ 2q, 0 ≤ p. q

10 of 16 ≤m–1. Which one of the following functions describes the range-decoder?

a.

b.

c.

d.

( X .X .L.X .X ) ( X +X +L + X ) ( X ⊕ X ⊕L X ) p

q −1

p+1

q+1

q+2

p

p+1

(X

q+1

(X

p

(X

q+1

q

m −1

q

+X q+2 + L + X m −1

)

d.

+X p+1 + L + X q−1 + X q ) .L.X m −1

)

( X +X +X +L + X ) 0

(X 66.

c.

q+1

1

2

.X q+2 .L.X m −1

q

)

68.

A silicon transistor with VBE sat = 0.8 V, βdc = 100 and VCE sat = 0.2 V is used in the

Consider the following circuit :

circuit shown below :

67.

What is the output voltage V0 in the above circuit ? a. 9.5 V b. 3 V c. 32.2 V d. 1 V If the coupling capacitors of a CE transistor amplifier is shorted, which one of the following graphs will represent the frequency response curve of the amplifier? (Av voltage gain, f = frequency in Hertz, Amax = maximum value of Av) a.

69.

a. J n Q n + K n Q n b. J n Q n + K n Q n c. J n Q n + K n Q n d. J n Q n + K n Q n 70.

b.

What is the minimum value of RC for which transistor is in saturation? a. 4286 Ω b. 4667 Ω c. 5000 Ω d. 1000 Ω For a JK flip-flop, Qn is output at time step tn. Which of the following Boolean expressions represents Qn+1 ?

Which one of the following statements is correct? In Intel 8085, me interrupt enable flip-flop is reset by a. DI instructions only b. system RESET only c. interrupt acknowledgement only d. either DI or system RESET or interrupt acknowledgement

71.

72.

73.

Match List I (Instruction) with List II Operation) for Intel 8085 and select the correct answer using the codes given below: List I A. PCHL B. SPHL C. XTHL D. XCHG List II 1. Exchange the top of the stack with the contents of HL pair 2. Exchange the contents of HL with those of DE pair 3. Transfer the contents of HL to the stack pointer 4. Transfer the contents of HL to the programme counter A B C D 3 4 1 2 a. b. 3 4 2 1 c. 4 3 2 1 d. 4 3 1 2 Match List I (Instruction) with List II (Application) and select the correct answer using the codes given below: List I A. SIM B. DAD C. DAA D. SPHL List II 1. 16-bit addition 2. Initializing the stack pointer 3. Serial output data 4. Checking the current interrupt mask setting 5. BCD addition A B C D 5 4 2 1 a. b. 3 1 5 4 c. 5 1 2 4 d. 3 4 5 1 Which one of the following statements is correct? a. ROM is a Read/Write Memory

74.

75.

76.

77.

78.

11 of 16 b. PC points to the last instruction that was executed c. Stack works on the principle of LIFO d. All instructions affect the flags Consider the following multiplication (10w1z)2 × (15)10 = (y01011001)2 Which one of the following gives appropriate values of w, y and z ? a. w = 0, y = 0, z = 1 b. w = 0, y = 1, z = 1 c. w = 1, y = 1, z = 1 d. w = 1, y = 1, z = 0 What must be the contents of the control word of Intel 8255 for Mode O(operation) and for the following ports configuration: Port A – output, Port B – output, Port Clower – output, Port Cupper — input ? a. 85 H b. 86 H c. 87 H d. 88H Which one of the following 8085 assembly language instructions does not affect the contents of the accumulator? a. CMA b. CMPB c. DAA d. ADDB MC 1488 and MC 1489 are needed when using RS 232 for which one of the following? a. To convert the logical levels at the receiving and sending ends of RS 232 into TTL compatible levels b. To convert the TTL level voltages at the sending and receiving ends of RS 232 to ± 12 V level c. They are not required while using RS 232 d. To improve the current drive of the RS 232 output signals Which one of the following statements for Intel 8085 is correct? a. Program counter (PC) specifies the address of the instruction last executed b. PC specifies the address of the instruction being executed

79.

80.

81.

c. PC specifies the address of the instruction to be executed d. PC specifies the number of instructions executed so far Match List I (Interrupts) with List II (Corresponding Characteristics) and select the correct answer using the codes given below: List I A. TRAP B. INTR C. RST 7.5 D. RST 6.5 List II 1. Level triggered 2. Non maskable 3. For increasing the number of interrupts 4. Positive edge triggered A B C D a. 2 4 3 1 b. 1 4 3 2 1 3 4 2 c. d. 2 3 4 1 What is the total number of memory locations and input-output devices that can be addressed with a processor having 16bits address bus, using memory mapped I/O ? a. 64 K memory locations and 256 I/O devices b. 256 I/O devices and 65279 memory locations c. 64 K memory locations and no I/O devices d. 64 K memory locations or input-output devices For Intel 8085, match List I (Addressing Mode) with List II (Instruction) and select the correct answer using the codes given below : List I A. Implicit addressing B. Register-indirect C. Immediate D. Direct addressing List II 1. JMP 3 FAO H 2. MOV A, M

82.

83.

84.

85.

12 of 16 3. LDA 03 FC H 4. RAL A B C D 4 1 2 3 a. b. 4 2 1 3 c. 3 2 1 4 3 1 2 4 d. A memory system of 64 kbytes needs to be designed with RAM chips of 1 kbyte each, and a decoder tree constructed with 2 : 4 decoder chips with “Enable” input. What is the total number of decoder chips ? a. 21 b. 64 c. 32 d. 25 Match List I with List II and select the correct answer using the codes given below: List I A. Monitor program B. Assembler C. Mnemonic D. Program counter List II 1. Used to indicate memory location 2. A combination of letters, symbols and numerals 3. A program that translates symbolic instructions into binary equivalent 4. An operating system A B C D 4 3 2 1 a. b. 4 3 1 2 c. 3 4 1 2 d. 3 4 2 1 Which one of the following statements is correct? In PCM, the conditional probability of error is proportional to a. noise power (N0) b. Peak signal energy (Emax) c.

N0

d.

E max

Which one of the following statements is correct?

13 of 16

86.

87.

88.

89.

90.

In TDM, non-essential frequency components of the modulating signal are removed by a. sampler b. attenuator c. pre-alias filter d. modulator Which one of the following statements is correct? For coherent detection of digital signals, the receiver must be a. synchronized in time only b. synchronized in phase only c. synchronized in time and phase d. unsynchronized A single-phase inverter has square wave output voltage. What is the percentage of the fifth harmonic component in relation to the fundamental component? a. 40% b. 30% c. 20% d. 10% For a binary symmetric channel, which one of the following is the correct expression for entropy ? (p = conditional probability of error). a. p log2 (1/p) + (1 – p) log2{1/(1–p)} b. p log2 (1/(1–p)} + (1 – p) log2 (1/p) c. 2 log2 (1/p) + 2 log2 {1/1–p)} d. (1–p) {log2 (1/p)} + log2 {(1/1–p)} In amplitude modulation, the modulation envelope has a peak value which is double the unmodulated carrier value. What is the value of the modulation index ? a. 25% b. 50% c. 75% d. 100% S1 and S0 denote the signal at input and output of a linear network. Ni and N0 are the corresponding noises. Which one of the following is the correct expression for noise figure of the network? SiS0 a. Ni N 0

Si N i b. S0 N 0

91.

92.

93.

94.

c.

Si N 0 S0 N i

d.

S0 N 0 Si N i

Which one of the following statements is correct? One hundred percent modulation of the carrier for the broadcast FM radio band is achieved when a. carrier frequency changed by ± 100% b. carrier envelope changed by ± 100% c. carrier frequency changes by ± 75 kHz d. audio frequency changes by ± 15 kHz In case of data transmission, which one of the following systems will give the maximum probability of error? a. ASK b. FSK c. PSK d. DPSK Which one of the following statements is correct? The type of modulation used generally in TV transmission for video and audio signals, respectively are a. FM and AM b. FM and FM c. AM and AM d. AM and FM Match List I (FM Service Type) with List II (Channel Bandwidth) and select the correct answer using the codes given below : List I A. Commercial FM radio broadcast B. Television sound C. Police, fire, ambulance. etc. D. Amateur radio List II 1. 100 kHz 2. 15 kHz 3. 200 kHz 4. 20 kHz A B C D

95.

96.

97.

98.

a. 4 2 3 1 4 1 3 2 b. c. 3 1 4 2 d. 3 2 4 1 Which one of the following statements is correct? The capacitor charging time in the AM envelope demodulator is based on the time for one a. half cycle of the carrier frequency b. quarter cycle of the carrier frequency c. half cycle of the lowest audio frequency d. quarter cycle of the highest audio frequency Which one of the following statements is correct? Quantising noise is produced in a. all pulse modulation systems b. PCM c. all modulation systems d. FDM Which one of the following statements is correct? The equalizing pulses in television transmission are sent during a. vertical blanking b. horizontal blanking c. horizontal retrace d. picture forward trace Which one of the following represents the Fourier Transform X(jw) of the signal x(t) = t e–at u(t) ? jw a. X(jw) = a+jw ( ) b. X(jw) =

c. X(jw) = d. X(jw) = 99.

100.

101.

102.

103.

14 of 16 a. 1 to 2 microseconds b. 50 to 200 microseconds c. 500 to1000 microseconds d. 1 to 2 milliseconds Which one of the following statements is correct? A triac is a a. 2 terminal switch b. 2 terminal bilateral switch c. 3 terminal unilateral switch d. 3 terminal bidirectional switch Which one of the following is the most suitable device for a d.c-d.c. converter? a. BJT b. GTO c. MOSFET d. Thyristor Which one of the following is correct? In a switched capacitor network for VAr compensation the SCRs are commutated by a. forced commutation b. resonant commutation c. natural commutation d. delayed commutation Which one of the following shows current fold back characteristics curve for an SCR controlled shunt regulated power supply ? a.

b.

jw

( a+jw )

2

( a+jw )

2

c.

jw

1

( a+jw )

2

Which one of the following statements is correct? The turn off times of converter grade SCRs are normally in the range of

d.

109.

104.

105.

106.

107.

108.

Which one of the following statements is correct? In a transistor, the reverse saturation current ICO a. doubles for every 100 C rise in temperature b. doubles for every 10 C rise in temperature c. increases linearly with temperature d. decreases linearly with temperature Which one of the following statements is correct? In a thyristor, the holding current IH is a. more than the latching current IL b. less than IL c. equal to IL d. equal to zero Which one of the following statements is correct? For an SCR, dv/dt protection is achieved through the use of a. RL in series with SCR b. RC across SCR c. L in series with SCR d. RC in series with SCR A power diode is in the forward conduction mode and the forward current is now decreased. The reverse recovery time of the diode is tr and the rate of fall of the diode current is di/dt. What is the stored charge ? a. (di/dt) . tr b. 1/2 (di/dt) .tr2 c. (di/dt) . tr2 d. 1/2 (di/dt) . tr In the buck-boost converter, what is the maximum value of the switch utilization factor ? a. 1.00 b. 0.75 c. 0.50 d. 0.25

110.

111.

112.

113.

15 of 16 Which one of the following statements is correct? In order to get best results per unit cost, the heat sinks on which the thyristors are mounted, are made of a. aluminium b. copper c. nickel d. stainless steel Which one of the following capacitors is suitable for compensation of harmonic and reactive power? a. Mica capacitor b. Glass capacitor c. Polypropylene capacitor d. Electrolytic capacitor Which one of the following statements is correct? The function of bleeder resistor in a power supply is a. to ensure a minimum current drain in the circuit b. to increase the output d.c. voltage c. to increase the output current d. same as that of a load resistor Which one of the following is used as the main switching element in a switched mode power supply operating in 20 kHz to 100 kHz range? a. Thyristor b. MOSFET c. Triac d. UJT Assertion (A) : The main advantage of decoupled load flow (DLF) method as compared to Newton Raphson method is its reduced memory requirements in storing the Jacobian. Reason (R) : An important characteristic of any practical electric power transmission system operating in steady state is the strong interdependence between the real power and bus voltage angles, and between the reactive powers and voltage magnitudes. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A

114.

115.

116.

117.

c. A is true but R is false d. A is false but R is true Assertion (A) : A single-phase induction motor is not self-starting as such. Reason (R) : A single-phase induction motor develops only pulsating magnetic field which provides zero torque at standstill. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : In the “3-point” type of starter of a d.c. series motor, the “holding coil” for holding the starter handle in the “ON” stud is connected in such a manner that it is short-circuited when the “over load” relay picks up. Reason (R) : In a d.c. series motor starter, to guard against “racing” due to sudden large reduction of shaft-load, the “holding coil” is connected in series with the armature circuit and the series field winding. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : A synchronous motor operating from constant voltage and constant frequency source has a substantially constant resultant air-gap flux. Reason (R) : If the d.c. field current in this motor can set up the required resultant airgap flux, the lagging reactive volt-amperes drawn from a.c. source is zero. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Transformer is not used in a d.c. line.

118.

119.

120.

16 of 16 Reason (R) : Losses in the d.c. circuit are not negligible. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Δ-connected tertiary windings tend to act as an automatic feedback control system. Reason (R) : In the event of unbalanced secondary load currents, both secondary and primary load voltages are restored, to their normal phase magnitude and angle. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : If the load requirement of a synchronous motor exceeds the pull-out torque, the synchronous motor action is lost. Reason (R) : Rotor and stator fields are no longer stationary with respect to each other. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : In a thyristor-controlled reactor, a minimum of 3 to 4 thyristors must be provided as redundant in capacitor switching. Reason (R) : It is desired to protect the whole string against unexpected transients. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true

I.E.S (OBJ) - 2005

1 of 16

ELECTRICAL ENGINEERING PAPER–II 1.

C. Sumpner’s Test D. Load Test List II 1. Copper loss and iron loss 2. Total losses 3. Iron loss 4. Copper loss Codes; A B C a. 3 4 1 b. 2 1 4 3 1 4 c. d. 2 4 1

A coil of 1000 turns is wound on a core. A current of 1 A flowing through the coil creates a core flux of 1 mWb. What is the energy stored in the magnetic field?

1 J 4 1 b. J 2 c. 1 J d. 2 J Match List I (Type of Coil) with List II (Use of Coil) and select the correct answer using the code given below the lists: List I A. Sandwitch coils B. Disc coils C. Cross-over coils D. Spiral type List II 1. Low voltage coils for currents above 100 A 2. High voltage windings of small transformers 3. Cooling oil is in contact with each turn of the winding 4. Shell-type transformer core Codes; A B C D a. 2 3 4 1 b. 4 1 2 3 c. 2 1 4 3 d. 4 3 2 1 Match List I (Test) with List II (Quantities) and select the correct answer using the code given below the lists: List I A. O C Test B. S C Test

a.

2.

3.

D 2 3 2 3

4.

The exact equivalent circuit of a twowinding transformer is given in the figure given above. For affecting simplification, the parallel magnetising branch, consisting of RC and XQ is shifted to’ the left of the primary leakage impedance (r1 + jx1). This simplification introduces the inaccuracy, in the neglect of: a. Voltage-drop in ‘the primary impedance due to the secondary current b. Voltage-drop in the primary impedance due to the exciting current c. Voltage-drop in the secondary impedance due to the exciting current d. Reduction in values of RC and XQ of the exciting circuit 5.

2 of 16

6.

A single-phase, 10 kVA, 2000/200 V, 50 Hz transformer is connected to form an auto transformer as shown in the figure given above. What are the values of V1 and I2 respectively? a. 2200 V, 55 A b. 2200 V, 45 A c. 2000 V, 45 A d. 1800 V, 45 A Three single phase 11000/220 V transformers are connected to form 3phase transformer bank. High voltage side is connected in star, and low voltage side is in delta. What are the voltage ratings and turn ratio of 3-phase transformer? a. 19052/220V, 50

4. Sumpner’s test Codes; A B a. 1 2 b. 3 4 c. 1 4 3 2 d.

c. 11000/381 V, 50 3 7.

8.

D 3 1 3 1

9.

b. 19052/220V, 50 3

d. 11000/220 V, 50 If the wave form of the voltage impressed on the primary of a Y — Δ bank contains 5th harmonics, what are the wave forms of the resultant voltages of the primary and the secondary? Primary Secondary a. Peaked Peaked b. Peaked Flat-topped c. Flat-topped Peaked d. Flat-topped Flat-topped Match List I (Machine) with List II (Test) and select the correct answer using the code given below the lists: List I A. DC Motors B. Single phase transformers C. 3-phase induction motors D. Salient pole alternators List II 1. Slip test 2. Blocked rotor test 3. Swinburne’s test

C 4 2 2 4

10.

Two single phase transformers A and B are connected in parallel, observing all requirements of a parallel operation, except that the induced voltage Ea is slightly greater than Eb; Zea and Zeb being the equivalent impedances of A and B, both referred to the secondary side. Under this operating condition with the primary bus-bars being energized, a circulating current will flow: a. Only in the secondary windings of A and B b. In both the primary and the secondary windings of A and B c. In both the primary and the secondary windings of A and B, as well as in the primary side network d. In the primary and the secondary windings of A and B, and boost the voltages on the secondary side of both A and B The armature resistance of a 6-pole lap wound d.c. machine is 0.05Ω. If the armature is rewound as a wave-winding, what is the armature resistance? a. 0.45 Ω b. 0.30 Ω c. 0.15 Ω

11.

d. 0.10 Ω In a d.c. compound generator, “flatcompound” characteristic, required for certain applications, may be obtained by connecting a variable resistance:

12.

13.

14.

a. Across the series field b. In series with the series field c. In parallel with the shunt field d. In series with the shunt field A 6-pole lap wound d.c. machine armature has 720 conductors and it draws 50 A from supply mains. What is the flux distribution produced by the armature reaction per pole? a. Rectangular in wave shape with a peak of 500 AT b. Rectangular in wave shape with a peak of 100 AT c. Triangular in wave shape with a peak of 500 AT d. Triangular in wave shape with a peak of 1000 AT Match List I with List II and select the correct answer using the code given below the lists: List I (DC Motor) A. Cumulatively compound motor B. Differentially compound motor C. Series motor D. Shunt motor List II (Characteristic) 1. Fairly constant speed irrespective of the load 2. It may start in reverse direction 3. Definite no-load speed 4. Is never started without load Codes; A B C D a. 4 1 3 2 b. 3 2 4 1 c. 4 2 3 1 d. 3 1 4 2 A synchronous motor is operated from a bus voltage of 1.0 pu and is drawing 1.0 pu zero power factor leading current. Its synchronous reactance is 0.5 pu. What is the excitation emf of the motor? a. 2.0 b. 1.5 c. 1.0 d. 0.5

15.

16.

17.

18.

19.

3 of 16 In the measurement of Xd, Xq (in ohms), following data are obtained by the slip test on a salient pole machine: Id max = 10 A Id min = 6.5 A Vd max = 30 V Vd min = 25 V Which one of the following is correct? a. Xd = 3, Xq = 3.86 b. Xd = 4.615, Xq = 2.5 c. Xd = 3, Xq = 2.5 d. Xd = 4.61, Xq = 3.86 What are the conditions to be satisfied for alternator to be synchronized with an incoming supply? 1. Equal voltage 2. Equal frequency 3. Same power rating 4. Same phase sequence Select the correct answer using the code given below: a. 2, 3 and 4 b. 3 and 4 c. 1, 2 and 3 d. 1, 2 and 4 The stator and the rotor of a 3-phase, 4pole wound-rotor induction motor are excited, respectively, from a 50 Hz and a 30 Hz source of appropriate voltage. Neglecting all losses, what is/are the possible no-load speed/speeds at which the motor would run? a. 1500 rpm and 900 rpm b. 2400 rpm and 600 rpm c. 2400 rpm only d. 600 rpm only A starting torque of 80 Nm is developed in an induction motor by an auto-transformer starter with a tapping of 30%. If the tapping of auto-transformer starter is 60%, then what is the starting torque? a. 40 Nm b. I60 Nm c. 240 Nm d. 320 Nm Which of the following methods are suitable for the speed control of squirrel cage induction motors?

20.

21.

1. Voltage control 2. Rotor resistance control 3. Frequency control 4. Pole changing method Select the correct answer using the codes given below: a. 2, 3 and 4 b. 1, 3 and 4 c. 1, 2 and 3 d. 2 and 4 A capacitor-start single-phase inductor motor is used for: a. Easy to start loads b. Medium start loads c. Hard to start loads d. Any type of start loads In hand-tool applications, which one of the following single phase motors is used? a. Shaded pole motor b. Capacitor start motor c. Capacitor run motor d. AC series motor

25.

26.

27.

22.

23.

24.

What is the phase displacement between primary and secondary voltages for a stardelta, 3-phase transformer connection shown above? a. 300 lagging b. 30° leading c. 0° d. 180° What is the shunt resistance component in equivalent circuit obtained by no load test of an induction motor representative of? a. Windage and frictional losses only b. Core losses only c. Core, windage and frictional losses d. Copper losses A 400 V D.C. shunt motor takes 5 A at noload. Ra = 0.5 ohms, Rf = 200 ohms. What is the ratio of speed from full load to no-

28.

4 of 16 load, when the D.C. shunt motor takes 50 A on full load? a. 0.94 b. 0.8 c. 0.6 d. 0.4 A linear ac servomotor must have: a. High rotor resistance b. High rotor reactance c. A large air gap d. Both high rotor resistance and reactance A wound rotor induction motor runs with a slip of 0.03 when developing full load torque. Its rotor resistance is 0.25 ohm per phase. If an external resistance of 0.50 ohm per phase is connected across the sup rings, what is the slip for full torque? a. 0.03 b. 0.06 c. 0.09 d. 0.1 Match List I (Characteristics) with List II (Relation) and select the correct answer using the code given below the lists List I A. Open circuit characteristics B. Internal characteristics C. External characteristics D. Load saturation curve List II 1. V v. If 2. E0 v. If 3. E v. Ia 4. V v. I Codes; A B C D a. 4 3 2 1 b. 2 1 4 3 c. 4 1 2 3 d. 2 3 4 1 In the block diagram of a separately excited dc motor, how does the armature induced emf appear as? a. Positive feedback

5 of 16

29.

30.

31.

32.

b. Negative feedback c. Disturbance input d. Output A Buchholz relay is used for: a. Protection of a transformer against all internal faults b. Protection of a transformer against external faults c. Protection of a transformer against both internal and external faults d. Protection of induction motors On what basis is the insulation level of a 400 kV, EHV overhead transmission line decided? a. Lightning over voltage b. Corona inception voltage c. Switching over voltage d. Radio and TV interference On which one of the following cycles does a modern steam power plant work? a. Carnot cycle b. Rankine cycle c. Otto cycle d. Bell-Coleman cycle Match List I (Classification of Head) with List II (Type of Turbines) and select the correct answer using the code given below the lists: List I A. Low head, 2 – 15 m B. Medium head, 15 – 70 m C. High head, 70 – 500 m D. Very high head > 500 m List II 1. Propeller or Kaplan 2. Kaplan or Francis 3. Pelton 4. Francis or Pelton Codes; A B C D a. 1 3 4 2 b. 4 2 1 3 c. 1 2 4 3 4 3 1 2 d.

33.

A zero-sequence network of a 3-phase transformer is given above. Z0 is the zerosequence impedance of the transformer. What is the type of transformer connections? a.

b.

c.

d.

34.

The charging reactance of 50 km length of the line is 1500Ω. What is the charging reactance for 100 km length of the line? a. 1500 Ω b. 3000 Ω c. 750 Ω

35.

36.

d. 600 Ω Equivalent n model is quite suitable for analyzing the performance of transmission line of a. 50 km length b. 150 km length c. 250 km length d. All of the above lengths Consider the following statements in respect of load flow studies in power systems: 1. Bus admittance matrix is a sparse matrix. 2. Gauss-Seidel method is preferred over Newton-Raphson method for load flow studies.

37.

3. One of the buses is taken as slack bus in load flow studies. Which of the statements given above are correct? a. 1, 2 and 3 b. 1 and 2 c. 1 and 3 d. 2 and 3 Buses for load flow studies are classified as: (i) Load bus (ii) PV bus (iii) Slack Bus Which one of the following is the correct combination of the pair of quantities specified having their usual meaning for different buses? Load bus PV bus Slack bus a. P, | v |

P, Q

P, δ

b. P, Q

P, | v |

| v |, δ

c. | v |, Q

P, δ

P, Q

d. P, δ

Q, | v |

Q, δ

40.

41.

38. 42.

39.

A sample power system network is shown in the figure given above. The reactances marked are in pu. What is the pu value of Y22 of the Bus Admittance Matrix (YBUS)? a. j 10.0 b. j 0.4 c. – j 0.1 d. – j 20.0 The direct axis reactance Xd of a synchronous generator is given as 0.4 Pu based on the generator’s name plate rating of 10 kV, 75 MVA, The base for calculation is 11 kV, 100 MVA. What is the pu value of Xd on the new base? a. 0.279 b. 0.578 c. 0.412 d. 0.44

6 of 16 A fault occurring at the terminals of an unloaded synronous generator operating at its rated voltage has resulted in the following values of currents and voltages: Iao = j 2.37 pu, Ial = - j 3.05 pu, Ia2 = j = 0.68 pu, Vao = Va1 = Va2 = 0.237 pu Which one of the following faults has occurred? a. L - L fault b. L - G fault c. L – L - G fault d. L – L – L fault For 800 MJ stored energy in the rotor at synchronous speed, what is the inertia constant H for a 50 Hz, four pole turbogenerator rated 100 MVA, 11kv? a. 2.0 MJ/MVA b. 4.0 MJ/MVA c. 6.0 MJ/MVA d. 8.0 MJ/MVA A 50 Hz, 17.32 kV generators is connected to a power system. The system reactance and capacitance per phase are 10 mH and 0.02 mF, respectively. What is the maximum voltage across the contents of the circuit breaker at an instant when it passes through zero? a. 28.28 kV b. 29.28 kV c. 30.28 kV d. 31.28 kV

43.

The distribution system shown in figure given above is to be protected by over current system of protection. At which locations are directional over current relays required for proper fault discrimination? a. 1 and 4 b. 2 and 3

44.

45.

c. 1, 4 and 5 d. 2, 3 and 5 Match List I (Relay) with List II (Protected Power system Component) and select the correct answer using the code given below the lists: List I A. Distance relay B. Under frequency relay C. Differential relay D. Buchholz relay List II 1. Transformers 2. Turbines 3. Busbars 4. Shunt capacitors 5. Alternators 6. Transmission lines Codes; A B C D a. 6 5 3 1 b. 3 1 4 2 c. 6 1 3 2 d. 3 5 4 1 Which type of connection is employed for current transformers for the protection of star-delta connected 3-phase transformer? a. Delta-delta b. Star-star c. Star-delta d. Delta star

46.

For the circuit shown in figure given above, assume β = hFE = 100. The transistor is in a. Active region and VCE = 5 V b. Saturation region c. Active region and YCE = 1.42 V d. Cut-off region

47.

48.

49.

7 of 16 Two p-n junction diodes are connected back to back to make a transistor. Which one of the following is correct? a. The current gain of such a transistor will be high b. The current gain of such a transistor will be moderate c. It cannot be used as a transistor due to large base width d. It can be used only for pnp transistor Match List I with List II and select the correct answer using the code given below the lists List I A. Modified during fetch phase B. Holds subscripts of arrays C. Needed by the DEBUG program D. Calculates addresses of data in datasegment List II 1. DI 2. DS 3. IP 4. TF Codes; A B C D a. 2 4 1 3 3 1 4 2 b. c. 2 1 4 3 d. 3 4 1 2 Consider the following statements about register indirect addressing: 1. It helps in writing code that executes faster. 2. It helps in writing compact code. 3. It allows reuse of memory CPU data transfer instruction. 4. It is essential for stack operations. Which of the statements given above are correct? a. 1, 3 and 4 b. 1, 2 and 4 c. 2, 3 and 4 d. 1, 2 and 3

50.

51.

52.

53.

Which of the following does not take place when 8085 processor is reset? a. 8055 gives reset out signal to reset external hardware b. 8085 resets program counter to FFFFH c. The interrupt system is disabled d. The busses are tristated Memory chips of four different sizes as below are available: 1. 32 k × 4 2. 32 k × 16 3. 8 k × 8 4. 16 k × 4 All the memory chips as mentioned in the above list are Read/Write memory. What minimal combination of chips or chip alone can map full address space of 8085 microprocessor? a. 1 and 2 b. 1 only c. 2 only d. 4 only A good assembly language programmer should use general purpose registers rather than memory in maximum possible ways for data processing. This is because: a. Data processing with registers is easier than with memory b. Data processing with memory requires more instructions in the program than that with registers c. Of limited set of instructions for data processing with memory d. Data processing with registers takes fewer cycles than that with memory. Which of the following notations have two representations of zero? 1. 1’s complement with radix of number being 2 2. 7’s complement with radix of number being 8 3. 9’s complement with radix of number being 10 4. 10’s complement with radix of number being 10 Select the correct answer using the code given below:

54.

8 of 16 a. 1, 2 and 4 b. 1 and 3 c. 2, 3 and 4 d. 1, 2 and 3 Consider the following 8085 instructions: ANA A, ORA A, XRA A, SUB A, CMP A.

55.

56.

57.

Now, consider the following statements: 1. All are arithmetic and logic instructions. 2. All cause the accumulator to be cleared irrespective of its original contents. 3. All reset the carry flag. 4. All of them are 1-byte instructions. Which of the statements given above is/are correct? a. 1, 2, 3 and 4 b. 2 only c. 1, 2 and 4 d. 1, 3 and 4 INR instruction of 8085 does not affect carry flag. Which of the following is correct about INR instruction? a. Overflow cannot be detected b. Overflow can be detected c. If a programme requires overflow to be detected, ADD instruction should be used instead of INR d. It can be used to increase the contents of the BC register pair Which of the following is not correct? a. Bus is a group of wires b. Bootstrap is a technique or device for loading first instruction c. An instruction is a set of bits that defines a computer operation d. An interrupt signal is required at the start of every program The interrupt vector table IVT of 8086 contains a. The contents of CS and IP of the main program address to which the interrupt has occurred b. The contents of CS and IP of the main program address to which the control has to come back after the service routine

58.

59.

60.

c. The starting CS and IP values of the interrupt service routine. d. The starting address of the IVT Consider the following statements: 1. A total of about one million bytes can be directly addressed by the 8086 microprocessor. 2. 8086 has thirteen 16-bit registers. 3. 8086 has eight flags. V 4. Compared to 8086, the 80286 provides a higher degree of memory protection. Which one of the statements given above is correct? a. 2, 3 and 4 b. l, 3 and 4 c. 1, 2 and 4 d. 1, 2 and 3 The following sequences of instructions are executed by an 8085 microprocessor: 1000 LXI SP, 27FF 1003 CALL 1006 1006 POPH What are the contents of the stack pointer (SP) and the HL register pair on completion of execution of these instruction? a. SP = 27 FF, HL = 1003 b. SP = 27 FD, HL = 1003 c. SP = 27 FF, HL = 1006 d. SP = 27 FD, HL = 1006 Consider the program given below, which transfers a block of data from one place in memory to another: MVIC OBH LXIH 2400 LXID 3400 L1:MOV AM STAX D INR L INRE DCRC JNZ LI What is the total number of memory accesses (including instruction fatches) carried out

61.

62.

9 of 16 a. 118 b. 140 c. 98 d. 108 When an 8086 executes an INT type instruction, it: a. Resets both IF and TF flags b. Resets all flags c. Sets both IF and TF d. Resets the CF and TF An AM voltage signal s(t), with a carrier frequency of 1.15 GHz has a complex envelope g(t) = AC [1+ m(t)], AC = 500 V, and the modulation is a 1 kHz sinusoidal test tone described by m(t) = 0.8 sin (2 π × 103t),

63.

appears across a 50Ω resistive load. What is the actual power dissipated in the load? a. 165kW b. 82.5kW c. 3.3 kW d. 6.6 kW A broadcast AM radio transmitter radiates 125 kW when the modulation percentage is 70. How much of this is carrier power? a. ≈ 25 kW b. ≈ 50 kW c. ≈ 75 kW

64.

65.

d. ≈ 100 kW When a radio receiver is tuned to 555 kHz, its local oscillator provides the mixer with an input at 1010 kHz. At the output, another signal is also received along with the desired signal. What is the frequency of the other station? a. 910 kHz b. 355 kl-Iz c. 455 kHz d. 1465 kHz Which of the following is not a component of PLL? a. Frequency multiplier b. Phase detector c. VXD d. Loop filter

10 of 16 66.

67.

68.

69.

70.

Which of the following modulated signals can be detected by an envelope detector? a. DSB-suppressed carrier b. DSB-full carrier c. Frequency modulated signal d. SSB-suppressed carrier A given AM broadcast station transmits an average carrier power output of 40 kW and uses a modulation index of 0.707 for sine wave modulation. What is the maximum (peak) amplitude of the output if the antenna is represented by a 50 Ω resistive load? a. soy b. 50 kV c. 3.414 kv d. 28.28 kv A microphone with inbuilt amplifier has an output noise level in a very quiet room of about 30 μV rms. The maximum output level is about 300 mV rms before severe distortion occurs. What dynamic range does this represent in dB? a. 4dB b. 36dB c. 40dB d. 80dB Which one of the following statements is correct? Noise has the greatest effect in a communication system when it interferes with the signal a. in the transmitter b. in the channel c. in the receiver d. in the transducer Match List I (Signal) with List II (Spectrum) and select the correct answer using the code given below the lists: List I A.

B.

C. Speech Signal D.

List II 1.

2.

3.

4.

Codes:

71.

72.

73.

A B C D a. 1 3 2 4 2 4 1 3 b. c. 2 3 1 4 d. 1 4 2 3 A converter which can operate both in 3pulse and 6-pulse modes is a a. 1-phase full converter b. 3-phase half-wave converter c. 3-phase semi converter d. 3-phase full converter Analog data having highest harmonic at 30 kHz generated by a sensor has been digitized using 6-level PCM. What will be the rate of digital signal generated? a. 120 kbps b. 200 kbps c. 240 kbps d. 180 kbps The channel capacity of a noiseless channel is equal to a. Rate at which information is transmitted b. Signaling speed c. Bandwidth

74.

75.

76.

77.

d. Bandwidth-SNR product Match List I (Coding Technique in Digital Communication Systems) with List II (Purpose) and select the correct answer using the code given below the lists: List I A. Huffman code B. Error correcting code C. NRZ-coding D. Delta modulation List II 1. Elimination of redundancy 2. Reduces bit rate 3. Adapts the transmitted signal to the line 4. Channel coding Codes; A B C D a. 1 2 3 4 b. 3 4 1 2 c. 1 4 3 2 d. 3 2 1 4 To overcome slope overload problem, which type of the integrator is used in delta modulation? a. Fixed slope integrator b. Variable slope integrator c. Linear slope integrator d. Bipolar integrator Quantization noise occurs in a. Pulse amplitude modulation b. Pulse width modulation c. Pulse code modulation d. Pulse position modulation A gate turn off (GTO) thyristor has capacity to a. Amplify the gate-current b. Turn-off when positive current pulse is given at the gate c. Turn-off when a gate-pulse is given at the gate even though it is reverse biased d. Turn-off when a negative current pulse is given at the gate

78.

79.

80.

81.

82.

11 of 16 Power electronic device with poor turn-off gain is a. A symmetrical thyristor b. A conventional thyristor c. Power bipolar junction transistor d. Gate turn-off thyristor Match List I (Limiting Factor) with List II (Safe Operating Area Portion) and select the correct answer using the code given below the lists: List I A. The peak voltage limit B. Secondary breakdown limit. C. Power dissipation limit. D. Peak Current limit List II 1. PQ 2. QR 3. RS 4. ST Codes; A B C D a. 2 1 4 3 b. 4 3 2 1 c. 2 3 4 1 d. 4 1 2 3 Which one of the following statements is not correct? a. Power MOSFETs are so constructed as to avoid punch through b. In a power MOSFET, the channel length is relatively large and channel width is relatively small c. Power MOSFETs do not experience any minority carrier storage d. Power MOSFETs can be put in parallel to handle larger currents Carrier frequency gate drive is used for turn-on of a thyristor to reduce a. di/dt b. Turn-on time c. dv/dt d. Size of pulse transformer In a thyristor, di/dt protection is achieved by the use of

83.

84.

a. An inductance L in series with the thyristor b. A resistor in series with the thyristor c. RC in series with the thyristor d. RL in series with the thyristor The circulating current inductor is required in a dual converter to a. Improve the p.f. b. Smoothen the waveform of circulating current c. Limit the circulating current d. Increase the circulating current In a single-phase semi converter, with discontinuous conduction and extinction angle β < π, freewheeling action takes phase for

88.

89.

a. α b. π − β c. β − π 85.

d. Zero degree A three pulse converter is feeding a purely resistive load. What is the value of firing delay angle α, which dictates the boundary between continuous and discountinuous mode of current condution?

90.

a. α = 0° b. α = 30° c. α = 60° 86.

d. α = 150° For a single phase a.c. voltage controller feeding a resistive load, what is the power factor?

91.

(where α is firing angle measured from voltage zero.) a. Unity for all values of firing angle 1/2

⎡1 ⎧ 1 ⎫⎤ b. ⎢ ⎨(π − α ) + sin 2α ⎬⎥ 2 ⎭⎦ ⎣π ⎩

1/2

⎡1 ⎧ 1 ⎫⎤ c. ⎢ ⎨(π + α ) + sin 2α ⎬⎥ 2 ⎭⎦ ⎣π ⎩

1/2

⎡1 ⎧ 1 ⎫⎤ d. ⎢ ⎨(π + α ) − sin 2α ⎬⎥ 2 ⎭⎦ ⎣π ⎩

87.

Triacs cannot be used in AC voltage regulator for a a. Resistive load

92.

12 of 16 b. Back emf load c. Inductive load d. Resistive inductive load A motor armature supplied through phase controlled SCRs receives a smoother voltage shape at a. High motor speed b. Low motor speed c. Rated motor speed d. None of the above Which one of the following statements is correct? A voltage source inverter is normally employed a. when the source has low impedance and load has high reactance. b. when the source has high impedance and load has low reactance. c. when both the source and load have high values of impedance and reactance respectively. d. when both the source and load have high values of impedance and reactance respectively. The corona loss on a particular system at 50 Hz is 1 kW/ km per phase. What is the corona loss at 60 Hz in kW/km per phase? a. 0.83 b. 1.0 c. 1.13 d. 1.2 Consider the following statements: In memories, 1. ROMs are used for temporary program and data storage. 2. Dynamic RAM is less expensive than static RAM. 3. MASK ROM is used in high volume microprocessor based system. Which of the statements given above is/are correct? a. 1 only b. 1 and 2 c. 2 and 3 d. 1, 2 and 3 In a p-type silicon sample, the hole concentration is 2.25 ×x 1015/cc. If the

93.

94.

95.

intrinsic carrier concentration is 1.5 × 10 10 /cc, what is the electron concentration in the p-type silicon sample? a. zero b. 10 10/cc c. 10 5/cc d. 1.5 × 10 25/cc What is the reverse recovery time of a diode when switched from forward bias VF to reverse bias VR? a. Time taken to remove the stored minority carriers b. Time taken by the diode voltage to attain zero value c. Time to remove stored minority carriers plus the time to bring the diode voltage to reverse bias VR d. Time taken by the diode current to reverse Which one of the following statements is correct? In a transistor, a. ICBO is greater than ICEO, and does not depend upon temperature b. ICBO is greater than ICO, and doubles for every ten degrees rise in temperature c. ICBO is equal to ICO, and double for every ten degrees rise in temperature d. ICEO is equal to ICO and doubles for every ten degrees rise in temperature Consider following statements: 1. BJT is a current controlled device with high input impedance and high gain bandwidth. 2. FET is a voltage controlled device with high input impedance and low gain bandwidth. 3. UJT is a negative resistance device and can be used as an oscillator. 4. BJT, FET and UJT can all be used for amplification. Which of the statements given above are correct? a. 1 and 2 b. 2 and 3 c. 3 and 4 d. 1 and 4

96.

13 of 16 The dynamic transfer characteristics of a transistor is represented by

iC = A1ib + A2ib2 Where A1 and A2 are constants. If input singnal ib = I1 cos ω1t + I 2 cos ω2t the output will contain a. ω1 , ω2 , 2ω1 , 2ω2 b. dc term, ω1 , ω2 , ω1 + ω2 , ω1 − ω2 c. dc term, ω1 , ω2 , 2ω1 , 2ω2 , 2ω1 + 2ω2 , 2ω1 − 2ω2 d. dc term, ω1 , ω2 , 2ω1 , 2ω2 , ω1 + ω2 , ω1 − ω2 97.

98.

99.

Find the break region (voltage range) over which the dynamic resistance of a diode is multiplied by a factor of 1000. Let this region be contained between v1 and v2, then is |v1 - v2| given by a. logC (1000 VT) b. 1000VT c. (loge103) VT d. The value cannot be computed with the given data An emitter in a bipolar junction transistor is doped much more heavily than the base as it increases the a. Emitter efficiency b. Base transport factor c. Forward current gain d. All the three given above Match List I (Type of Device) with List II (Characteristics/Application) and select the correct answer using the code given below the lists: List I A. Zener diode B. Tunnel diode C. Schottky diode D. Photo diode List II 1. Display panel 2. Voltage reference 3. Light detection 4. Negative resistance 5. High frequency switching Codes; A B C D

100.

a. 3 4 5 2 2 5 1 3 b. c. 3 5 1 2 d. 2 4 5 3 Match List I (Circuit Symbol) with List II (Device) and select the correct answer using the code given below the lists: List I A.

102.

B.

C.

D.

101.

List II 1. N-channel FET 2. Varactor 3. Tunnel diode 4. P channel MOSFET Codes; A B C D a. 3 2 1 4 b. 1 4 3 2 c. 3 4 1 2 d. 1 2 3 4 Match List I (Device) with List II (Application) and select the correct answer using the code given below the lists: List I A. p-n junction diode B. tunnel diode C. WET D. Schottky barrier diode List II 1. Microwave generator 2. Low frequency rectifier 3. High frequency rectifier

14 of 16 4. Voltage variable resistor Codes; A B C D a. 2 3 4 1 b. 4 1 2 3 2 1 4 3 c. d. 4 3 2 1 Consider the following statements: 1. A Hartley oscillator circuit uses a tapped inductor for inductive feedback. 2. Oscillator circuit can be operated in class A condition for better wave shape. 3. Frequency stabilization is obtained by use of automatic biasing. Which of the statements given above are correct? a. 1, 2 and 3 b. 1 and 2 c. 2 and 3 d. 1 and 3

103.

In the rectifier circuit shown above, what should be minimum peak-inverse-voltage (Ply) rating of the diode? a. 12 V b. 12 2 V c. 24 V d. 24 2 V 104.

Which one of the following statements is correct? In the case of load regulation a. when the temperature changes, the output voltage remains constant b. when the input voltage changes, the load current remains constant c. when the load’ changes, the load current remains constant d. when the load changes, the output voltage remains

105.

106.

107.

In a centre tap full wave rectifier, 100 V is the peak voltage between the centre tap and one end of the secondary. What is the maximum voltage across the reverse biased diode? a. 200 V b. 141V c. 100 V d. 86 V Match List I (Type of Logic) with List II (Characteristics/ Application) and select the correct answer using the code given below the lists: List I A. Direct coupled logic B. Diode transistor logic C. Emitter coupled logic D. Resistor transistor logic List II 1. Good for monolithic I.C. 2. Slow speed of operation 3. Very fast speed of operation 4. Current hogging Codes; A B C D a. 2 1 3 4 b. 4 3 1 2 c. 2 3 1 4 4 1 3 2 d. Which of the following statements is not correct? a.

110.

111.

X + XY = X

b. X ( X + Y ) = XY c.

X + XY = X

d. ZX + ZXY = ZX + ZY 108.

The Boolean expression YZ + XZ + XY is logically equivalent to

112.

a. YZ + X b. YZX + XYZ c. YX + XZ + XY 109.

d. XYZ + XYZ + XYZ + XYZ Which one of the following statements is correct?

113.

15 of 16 Removing the small resistance (-100Ω) in the collector lead of the pull-up transistor of a totem pole output gate, will result in a. reduced switching time from Vout (I) to Vout (O) b. incorrect operation of the gate c. lower power dissipation d. more noise generation in the power supply distribution at high frequencies In a ripple counter, the stage whose output has a frequency equal to 1/8th that of the clock signal applied to the first stage also has an output periodicity equal to 1/8th that of the output signal obtained from the last stage. The counter Is a. Modulo-8 b. Modulo-6 c. Modulo-64 d. Modulo-16 Consider the following statements: In amplifiers, 1. a complementary symmetry amplifier has 1 PNP and 1 NPN transistor. 2. a boot strap incorporates emitter follower. 3. the main function of transformer used in the output of a power amplifier is to increase its voltage gain. 4. the harmonic distortion of the signal produced in a RC coupled transistor amplifier is due to transformer itself. Which of the statements given above are correct? a. 1, 2 and 3 b. 2, 3 and 4 c. 1, 3 and 4 d. 1, 2 and 4 In a single stage RC-coupled amplifier stage, what are the phase shifts introduced at lower and upper 3-dB frequencies, respectively? a. 45°, 225° b. 45°, 135° c. 90°, 180° d. 45°, 180° Which one of the following statements is correct? A Darlington amplifier has a

114.

115.

116.

117.

a. large current gain and high input resistance b. large voltage gain and low output resistance c. small voltage gain and low input resistance d. small current gain and high output resistance The gain of a bipolar transistor drops at high frequencies. This is because of the a. Coupling and bypass capacitors b. Early effect c. Inter-electrode transistor capacitances d. Coupling and bypass capacitors, and inter-electrode transistor capacitances Assertion (A): Emitter coupled oscillator is capable of high frequency operation. Reason (R): It consists of saturating NPN BJTs. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): A pumped storage plant is very suitable for supplying peak loads. During off peak period, water is pumped back from tail race pond to head water pond. Reason (R): The starting time of pumped storage plant is very short. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): For obtaining improved magnetic properties, the transformer magnetic core is assembled using coldrolled silicon-steel sheets. Reason (R): The laminations for the core could be cut out of the cold-rolled silicon steel sheets, cutting either in the direction of rolling or transverse thereof, without

118.

119.

120.

16 of 16 affecting the magnetic properties in any way. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): In a d.c. generator, even though the armature magnetic field is in quadrature with the main magnetic field, each considered alone, the resultant magnetic field due to interaction of both the fields is shifted backwards by certain angle from the geometrical neutral axis depending upon the load. Reason (R): In a d.c. generator, the trailing pole-tips get magnetically saturated as the load reaches its rated value. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Vestigial Side Band (VSB) modulation is used for TV broadcasting. Reason (R): Video signals have negligible power at low frequencies. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): An FET operated crystal oscillator operates on the concept of feedback. Reason (R): The feedback is provided by the drain-to-gate capacitance Cdg a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true

I.E.S-(OBJ) 2006

1 of 15

ELECTRICAL ENGINEERING PAPER-II 1.

2.

3.

4.

5.

Which one of the following is employed as a moderator by CANDU type of slow thermal nuclear reactors? a. Water b. Heavy water c. Graphite d. Beryllium A power station has maximum demand of 15000 kW. The annual load factor is 50% and plant capacity factor is 40%. What is the reserve capacity of the plant? a. 1875 kW b. 3750 kW c. 6000 kW d. 7500 kW A power station’s plant load factor is defined as the ratio of a. the energy generated to that of maximum energy that could have been generated b. average load to peak load c. minimum load to peak load d. minimum load to average load In a 7/30 A.C. SR conductor why is grease put between steel and aluminium conductors ? a. To reduce corrosion by electrolytic action between zinc (galvanising agent on steel) and aluminium b. To reduce friction between the strands c. To reduce leakage of current from aluminium strands to steel strands d. To eliminate air pockets If X is the inductive reactance/phase and R is the resistance! phase of a short transmission line, what is the power factor angle of the load for maximum voltage regulation? a. cos–1 X/R b. tan–1 X/R c. cos–1 R/X

6.

d. tan–1 R/X For a loss-free long transmission line, the conventional line equations become, Vs = ( cos β l ) VR + ( j sin β l ) I R

⎛ j sin β l ⎞ Is = ⎜ ⎟ VR + ( cos β l ) I R ⎝ Zc ⎠ Which one of the following statements is correct? If the line is terminated at the receiving end by its natural load impedance Zc, then a. the voltage is constant in magnitude at all points along the line and, Vs and VR always remain in phase. b. the voltage is constant in magnitude at all points along the line but Vs advances in phase relative to VR by an angle β radians per km. c. the magnitude of the voltage along the line changes in proportion to the linelength, and the Vs and VR always remain m phase. d. the magnitude of the voltage along the line changes in proportion to the linelength, Vs advances in phase relative to VR by β radians per km. What is the approximate value of the surge impedance loading of a 400 kV, 3-phase 50 Hz overhead single circuit transmission line? a. 230 MW b. 400 MW c. 1000MW d. 1600MW Which one of the following statements is correct? The elements of each row of a YBUS matrix for load flow studies in power system add up to zero, a. always b. if the shunt admittances at the buses are ignored. and

7.

8.

9.

c. if mutual couplings between transmission lines are absent. d. if both (b) and (c) are satisfied. For a synchronous generator connected to an infinite bus through a transmission line, how are the change of voltage (ΔV) and the change of frequency (Δf) related to the active power (P) and the relative power (Q)? a. ΔV is proportional to P and Δf to Q b. ΔV is proportional to Q and Δf to P c. Both ΔV and Δf are proportional to P d. Both ΔV and Δf are proportional to Q

14.

10. 15.

11.

12.

13.

For the system shown in the diagram given above, what is a the transformer the line side of line-to-ground fault on equivalent to ? a. A line-to-ground fault on the generator side of the transformer b. A line-to-line fault on the generator side of the transformer c. A double line-to-ground fault on the generator side of the transformer d. A 3-phase fault on the generator side of the transformer For which one of the following types of motors, is the equal area criterion for stability applicable? a. Three-phase synchronous motor b. Three-phase induction motor c. D.C. series motor d. D.C. compound motor The steady state stability limits for round rotor and salient pole 3-phase synchronous generator are attained at the values of power angle δ a. = π/2, and = π/2, respectively b. < π/2, and < π/2, respectively c. < π/2, and = π/2, respectively d. = π/2, and < π/2, respectively A travelling wave due to lightning with an incident voltage V travels through the

16.

17.

18.

2 of 15 overhead, line of surge impedance of 400Ω and enters a cable of surge impedance of 40 Ω What is the voltage entering the cable at the junction? a. V/11 b. 4 V/11 c. 2 V/11 d. V To protect the power transformer (Y — Y with neutral grounded) against fault, what type of connection do the CTs have ? a. Δ—Y connection b. Δ—Δ connection c. Y—Y connection d. Y—Δ connection The operating point of RI amplifier m an AM receiver is normally biased in a. Class-A b. Class-B c. Class – C d. Class B-C condition Which one of the following signals can be applied to a delta modulator whose step size is 0.1 V and sampling frequency is 20 π kHz so that no slope overload occurs? a. 2 sin (1200 πt) b. 1 sin (2600 πt) c. 3 sin (1000 πt) d. 4 sin (400 πt) A sinusoidal signal with a random phase is given by x(t) = A sin [π/2 — (2π ft + θ)] with the probability density function ⎧1/ 2π , 0 ≤ θ ≤ 2π Pθ (θ ) = ⎨ otherwise ⎩ 0, What is the maximum amplitude of the autocorrelation function of this signal ? a. A b. A/2 c. A2 d. A2/2 Consider the following statements : 1. Indirect addressing is not possible for I/O mapped I/O port addresses. 2. Pointers cannot be used to access memory mapped I/O addresses.

19.

20.

21.

3. Fewer machine instructions can be used with I/O mapped I/O addressing as compared to memory mapped I/O addressing. 4. With an 8085 microprocessor, one can access at the most 512 devices with unique addresses using 1/0 mapped 1/0 addressing. Which of the statements given above are correct ? a. 1, 2 and 3 b. 2 and 4 c. 3 and 4 d. 1 and 3 Which one of the following instructions is a 3-byte instruction? a. M V I A b. L D A X B c. J M P 2050 d. MOV A, M Match List-I (interrupt) with List-II (Property) and select the correct answer using the code given below the Lists : List-I A. RST 7.5 B. RST 5.5 C. INTR D. TRAP List-II 1. Non -maskable 2. Edge sensitive 3. Level sensitive 4. Non-vectored A B C D 1 3 4 2 a. 2 4 3 1 b. 1 4 3 2 c. 2 3 4 1 d. The contents of memory locations 2000 H, 2001 H and 2002 H are AAH, BBH and CCH respectively. What are the contents of H and L registers after executing the following instructions in sequence ? LXI H, 2001 H LHLD 2001 H Select the correct answer using the codes given below :

22.

23.

24.

25.

26.

3 of 15 a. Contents of H and L registers are 20 H and 01 H, respectively b. Contents of H and L registers are AAH and BBH, respectively c. Contents of H and L registers are BBH and CCH, respectively d. Contents of H and L registers are CCH and BBH, respectively How many times will the following loop be executed? LXIB 0010 H LOOP : DCX B MOV A, B ORA C JNZ LOOP Select the correct answer using the code given below : a. 10 b. 100 c. 16 d. 15 In 8085, the DAA instruction is used for a. Direct Address Accumulator b. Double Add Accumulator c. Decimal Adjust Accumulator d. Direct Mess Accumulator Processor status word of 8085 microprocessor has five flags. Which are these five flags? a. S, Z, AC, P, CY b. S, OV, AC, P, CY c. S, X, OV, P, CY d. S, Z, AC, P, OV Suppose 64 kB, ROM ICs, are available in abundance. 1 MB ROM can be obtained from a. 16 ICs in a row b. 16 ICs in a column c. 8 ICs in a column and 2 ICs in a row d. None of the above Which one of the following is the software intercept of 8085 microprocessor? a. RST 7.5 b. RST 7 c. TRAP d. INT1R

27.

28.

29.

Match List-I (Device) with List-II (Application) and select the correct answer using the code given below the Lists : List- I A. Diode B. Transistor C. Tunnel Diode D. Zener Diode List-II 1. Amplifier 2. Oscillator 3. Rectifier 4. Voltage Regulator A B C D 4 1 2 3 a. 3 2 1 4 b. 4 2 1 3 c. 3 1 2 4 d. Match List-I (Type of Amplifier/ Configuration) with List-II (Characteristic Property) and select the correct answer using code given below the Lists : List- I A. Common emitter amplifier B. Emitter follower C. Common base amplifier D. Darlington pair List-II 1. Very low output resistance 2. Current gain ≈1 3. Beta multiplication 4. Very high power gain A B C D 4 1 2 3 a. 2 3 4 1 b. 4 3 2 1 c. 2 1 4 3 d. Match List-I (Type of Diode) with List-IT (Characteristics! Applications) and select the correct answer using the code given below the Lists : List-I A. Tunnel diode B. Zener diode C. Photodiode D. Schottky diode

30.

31.

4 of 15 List-II 1. Reverse current varies directly with the amount of light 2. Exhibits negative resistance region in its I-C characteristic 3. Uses only majority carriers and is intended for high frequency operations 4. Silicon p-n junction diode that is designed for limiting the voltage across the terminals in reverse bias A B C D 2 3 1 4 a. 1 4 2 3 b. 2 4 1 3 c. 1 3 2 4 d. Match List-I (Parameter) with List-II (Variation) and select the correct answer using the code given below the Lists : List- I A. Electron mobility around room temperature B. Energy gap C. Intrinsic carrier concentration D. Mole density (gm/mole) List-II 1. Increases with temperature 2. Decreases with temperature 3. Remains constant as temperature is varied A B C D 2 1 1 1 a. 1 2 1 3 b. 2 2 1 3 c. 2 2 1 1 d. Match List-I (Metal semiconductor Band Diagram under Equilibrium) with List-II (Type of Contact) and select the correct answer using the code given below the Lists : List-I

A.

B.

C.

32.

D. List - II 1. Rectifier to n-type 2. Ohmic to n-type 3. Rectifier to p-type 4. Ohmic to p-type A B C D 1 4 2 3 a. 1 4 3 2 b. 4 1 3 2 c. 4 1 2 3 d. Consider the following statements Data that are stored at a given address in a random access memory are lost 1. when power goes off. 2. when the data are read from the address. 3. when new data are written at the address. 4. because it is non-volatile memory. Which of the statements given above are correct? a. 1 and 2 b. 1, 2 and 4 c. 2 and 3 d. 1 and 3

34.

35.

36.

37.

33.

The circuit shown above is the Thevenin’s equivalent circuit of a centre-tapped full wave rectifier with diode forward resistance Rf = 100 Ω, transformer secondary coil resistance Rs = 30Ω, peak input voltage Vm = 10 V. What are the values of V and R0, respectively ? a. 10 V, 100 Ω

38.

5 of 15 b. 6.36 V,130 Ω c. 6.36 V,115 Ω d. 4.54 V, 130 Ω What is the value of the load angle when the power output of a salient pole synchronous generator is maximum? a. 00 b. 450 c. 90° d. None of the above Which one of the following statements is not correct in respect of synchronous machines ? a. In salient pole machines, the directaxis synchronous reactance is greater than the quadrature axis synchronous reactance. b. The damper bars help the motor to self-start. c. Short circuit ratio is the ratio of the field current required to produce the rated voltage on open circuit to the rated armature current. d. The V-curve of a synchronous motor represents the variation in the armature current with field excitation at a given output power. In which one of the following is reluctance power developed? a. Salient pole alternator b. Non-salient pole alternator c. Squirrel cage induction motor d. Transformer When the applied rated voltage per phase is reduced to one-half, the starting torque of a three-phase squirrel cage induction motor becomes a. 1/2 of the initial value b. 1/4 of the initial value c. Twice of the initial value d. 4 times of the initial value

The required load torque line intersects the resultant torque- speed characteristic of a 3-phase squirrel cage induction motor at points P, Q and R as shown in the figure above. Which is/are the stable opening point(s) ? a. P and Q b. Q and R c. P and R d. Only R

44.

39.

45.

40.

41.

42.

43.

Which of the points on the torque-speed curve of induction motor represent operation at a slip greater than the 1? a. W b. X c. Y d. Z If the load on an induction motor is increased from no load to full load, its slip and the power factor will, respectively a. decrease, decrease b. decrease, increase c. increase, decrease d. increase, increase The voltage actually, used for setting up of the useful flux in the air gap of a 3-phase induction motor is a. = Applied voltage b. > Applied voltage c. < Applied voltage d. = Rotor induced emf Which one of the following is the type of single phase induction motor having the highest power factor at full load? a. Shaded. pole type b. Split-phase type c. Capacitor-start type d. Capacitor-run type A single phase induction motor is running at N r.p.m. Its synchronous speed is Ns. If its slip with respect to forward field is s,

46.

47.

6 of 15 What is the slip with respect to the backward field? a. s b. — s c. (1 — s) d. (2 — s) Which one of the following has the highest numerical value in a stepper motor? a. Detent torque b. Holding torque c. Dynamic torque d. Ripple torque Match List-I (Power Station) with List-Il (Component) and select the correct answer using the code given below : List- I A. Hydroelectric power station B. Nuclear power station C. Steam power station D. Pressure gasification combined cycle power plant List-Il 1. Grate and stokers 2. Forebay 3. Pressurized water reactor 4. Fluidized bed gasifier A B C D 1 4 2 3 a. 2 3 1 4 b. 1 3 2 4 c. 2 4 1 3 d. In hydro power stations, what is an enlarged body of water just above the intake and used as a regulating reservoir, called ? a. Spillways b. Forebay c. Reservoir d. Penstock For variable heads of near about but less than 30 metres, which type of turbines is used in hydro power stations ? a. Pelton b. Kaplan c. Francis d. None of the above

48.

49.

Which one of the following parameters in an induction motor influences the magnetizing reactance to the maximum extent? a. Axial length of the rotor stack b. Axial length of the stator stack c. Radial length of air gap d. Number of slots on the stator Which one of the following equations represents the energy gap (EG) variation of silicon with temperature (T)? a. EG(T) = 2.11 – 3.60 × 10–4 T b. EG(T) = 1.21 – 3.60 × 10–4 T c. EG (T) = 1.41 – 2.23 × 10–4 T d. EG(T) = 0.785 – 2.23 × 10–4 T

53.

54.

50.

Consider the circuit given above where R is the diode forward resistance and RL the load resistance. What is the average rectified current equal to ? a. Vm / (RL + Rf) b. Vm / {π(Rf + RL)} c. 2Vm / π 51.

52.

d. Vm / { 2 (RL + Rf)) In a Hall effect experiment, a p-type semiconductor sample with hole concentration p1 is used. The measured value of the Hall voltage is now replaced by another p-type sample with hole concentration p2 where p2 = 2 p1, what is the new Hall voltage VH2? a. 2VH1 b. 4 VH1 c. (1/2) VH1 d. (1/4) VH1 What is the thermal runaway in a bipolar junction transistor biased in the active region due to ? a. Heating of the transistor emitter region b. Changes in ‘β’ which increases with temperature c. Base emitter voltage VBE which decreases with rise in temperature

7 of 15 d. Increase in reverse collector - base saturation current due to rise in internal device temperature The reverse saturation current of a Sibased p-n junction diode increases 32 times due to a rise in ambient temperature. If the original temperature was 400 C, what is the final temperature? a. 90°C b. 72°C c. 450 C d. 500 C What is the main difference between MOSFETs and BJTs in terms of their I — V characteristics? a. Current in quadratic with VGS for MOSFETs and linear with VBE for BJTs b. Current in linear with VGS for MOSFETs and exponential with VBE for BJTs c. Current is exponential with VGS/VBE in both these devices, but rise is faster in MOSFETs d. Current in quadratic with V for MOSFETs and exponential with VBE for BJTs

55.

56.

In the circuit given above, if the output is taken from point E instead of node C, what will be the result? a. An increase in the output impedance b. A reduction in the output impedance c. An increase in the input impedance d. A reduction in the input impedance If an input periodic signal with non-zero d.c. component is impressed upon a highpass RC circuit, what will be the d.c. component in the output waveform? a. Zero b. It depends on the value of the capacitor c. It depends on the value of the resistor

8 of 15 d. Same as that in input 57.

B.

58.

59.

What is represented by the digital circuit given above ? a. An SR flip-flop with A = S and B = R b. A JK flip-flop with A = K and B = J c. A JK flip-flop with A = J and B = K d. An SR flip-flop with A = R and B = S Which one of the following is not a characteristic of CMOS configuration ? a. CMOS devices dissipate much lower static power than bipolar devices b. CMOS devices have low input impedances c. CMOS devices have higher noise margins d. CMOS devices have much lower transconductance than bipolar devices For an n-type semiconductor having any doping level, which of the following hold(s) good :

61.

1. pn ND = n i2 2. pp ND = n i2 3. nn ND = n i2 4. pn nn = n i2

60.

Select the correct answer using the code given below : a. 1 and 4 b. 2 and 4 c. 3 and 4 d. Only 4 Match the I-V characteristics given below with Gunn diode, Photo diode and Tunnel diode.

A.

62.

C. Select the correct answer using the code given below : Gunn diode Photo diode Tunnel diode A B C a. B A C b. A C B c. B C A d. Consider the following statements : In frequency response of n-stage amplifiers, 1. lower cut-off frequency is (21/n–1) times that of a single stage. 2. upper cut-off frequency is (21/n–1) times that of a single stage. 3. lower cut-off frequency is (21/n–1)–1 times that of a single stage. 4. upper cut-off frequency is (21/n–1)–1 times that of a single stage. Which of the statements given above are correct ? a. 1 and 2 b. 1 and 3 c. 2 and 4 d. 3 and 4 Consider the following statements : An applied bias voltage in a p-n junction diode (n region positive with respect to p region) results in 1. increase in potential barrier. 2. reduction in space charge layer width. 3. increase in space charge layer width. 4. increase in magnitude of electric field. Which of the statements given above are correct ? a. 1 and 2 b. 1 and 3 c. 1 and 4 d. l, 3 and 4

63.

Which one of the following statements is correct in respect of a BJT? a. Avalanche multiplication starts when the reverse biased collector-base voltage VCB equals the avalanche breakdown voltage BVCBO. b. The early effect starts as soon as punch through occurs in a transistor. c. The small signal current gain hfe = large signal current gain hFE when ∂hFE/∂IC = 0. d. In the CE mode, a transistor can be cut off by reducing IB to zero.

66.

9 of 15 d. 2 kTBR A DSB-SC signal i generated using the carrier signal cos (wct + θ) and modulating signal m(t). What is the envelop detector output of this DSB-SC signal? a. m(t) cosθ b. | m (t) | c. m(t) tanθ d. m(t) sin θ

67.

64.

Which one of the following is the impulse response of a matched filter for a singla s(t) of the type shown above?

68. a.

b. 69. c.

65.

d. Which one of the following is the available noise power produced by a noisy resistor K? [k = Boltzmann Constant, T Temperature and B Bandwidth] a. kTB b. 4 kTh c. 4 kTBR

70.

Which one of the following sets correctly describes the Block I and Block II in the diagram given above? Block I Block II A. Integrator Phase modulator Frequency modulator B. Integrator C. Differentiator Phase modulator D. Differentiator Frequency modulator The original spectrum of a message contains 100 Hz, 200 Hz frequency components. it is amplitude modulated by a carrier of 0.9 kHz. Which frequency components are contained in the amplitude modulated signal spectrum? a. 900, 1000 and 1100 Hz b. 700, 800 and 900 Hz c. 700, 800, 900, 1000 and 1100 Hz d. 100, 200 and 900 Hz If two signals modulate the same carrier with different modulation depths of 0.3 and 0.9, the resulting modulation signal will a. be over-modulated b. have the resultant modulation limited to 1.0 c. have the resultant modulation index around 0.82 d. have the resultant modulation index around 0.95 Match List-I (Modulation) with List-Il (Application) and select the correct answer using the code given below: List- I A. Wind band FM

71.

72.

B. Narrow band FM C. AM D. VSB-AM List-II 1. Mobile communicator 2. Superimposition of binary waveform on carrier 3. TV video 4. TV audio 5. Medium wave broadcast A B C D 4 3 5 1 a. 5 1 2 3 b. 4 1 5 3 c. 5 3 2 1 d. Match List-I (Parameter) With List-II (Value of Parameter) and select the correct answer using the code given below: List-I A. Line blanking period B. Line synchronization pulse C. Vertical field pulse D. Duration of pre-equalizing pulse sequence List - II 1. 4.5 to 4.9 μs 2. 155 to 165 μs 3. 11.8 to 12.3 μs 4. 20,000 μs A B C D 3 1 4 2 a. 4 2 3 1 b. 3 4 1 2 c. 4 3 2 1 d. Which of the following are the advantages of FM broadcasting over AM broadcasting? 1. Better S/N ratio 2. Not subject to signal fading 3. Power efficiency is superior 4. Demodulation is simpler Select the correct answer using the code given below: a. 1 and 2 b. 1, 2 and 4 c. 2, 3 and 4

73.

74.

75.

76.

77.

10 of 15 d. 1 and 3 Consider the following statements about analog data-digital signal : 1. Amplifiers used in repeaters produce additive noise. 2. FDM is used for digital signals whereas TDM is used for analog signals. 3. With TDM there is no intermodulation noise whereas this is a concern for FDM. 4. Conversion to digital signalling allows the use of efficient digital switching techniques. Which of the statements given above are correct? a. 1 and 2 b. 3 and 4 c. 1, 2 and 3 d. 1, 2, 3 and 4 A resistor connected across the gate and cathode of an SCR a. increases dv/dt rating of SCR b. increases holding current of SCR c. decreases noise immunity of SCR d. increases turn-off time of SCR Turn-on of a thyristor takes place when a. anode to cathode voltage is positive b. anode to cathode voltage is negative c. there is a positive current pulse at the gate d. the anode to cathode voltage is positive and there is a positive current pulse at the gate Which is the most suitable power device for high frequency (>100 kHz) switching application? a. Power MOSFET b. Bipolar junction transfer c. Schottky diode d. Microwave transistor Match List-I with List-II and select the correct answer using the code given below the Lists : List-I A. Voltage source inverter B. Current source inverter C. Phase controlled a.c. to d.c. converter

78.

79.

80.

D. Cycloconverter List-II 1. Large source inductance 2. Poor power factor 3. Inverter limit 4. Small source inductance A B C D 4 2 3 1 a. 3 1 4 2 b. 4 1 3 2 c. 3 2 4 1 d. In a dual converter, the circulating current a. allows smooth reversal of load current, but increases the response time b. allows smooth reversal of load current with improved speed of response c. does not allow smooth reversal of load current, but reduces the response time d. flows if there is no interconnecting inductor Match List-I (Type of Fault) with List-Il (Type of Protection) and select the correct answer using the code given below: List- I A. External phase fault B. Faults between phases C. Phase to earth fault D. Overheating List-II 1. Differential protection 2. Earth fault relay 3. Over-current protection (inverse time delay o/c relay) 4. Thermal relay A B C D 3 1 2 4 a. 4 2 1 3 b. 3 2 1 4 c. 4 1 2 3 d. How many relays are used to detect inter phase fault of a three-line system ? a. One b. Two c. Three d. Six

81.

82.

83.

84.

11 of 15 Which is the main relay for protecting up to 90% of the transmission line-length in the forward direction? a. Directional over-current relay b. Mho relay c. Carrier-current protective relay d. Impedance relay High voltage d.c. transmission requires filters for a. current harmonics on a.c. side voltage harmonics on d.c. side b. voltage harmonics on a.c. side and current harmonics on d.c. side c. voltage harmonics on both a.c. and d.c. sides d. current harmonics on both a.c. and d.c. sides If p is the pulse number and n is an integer, what is the order of harmonics on a.c. side and d.c. side of an HVDC converter? a. (np + 1) and (np — 1), respectively b. (np — 1) and. np, respectively c. (np + 1) and np, respectively d. (np ± 1) and np, respectively In a biased step-graded p-n junction, what is the correct expression for the equilibrium contact potential (V0)? a. V0 = VTln (NA/ND n i2 ) b. V0 = VTln (ND/NA n i2 ) c. V0 = VTln (NAND / n i2 ) d. V0 = VTln (n i2 /NAND)

85.

where VT ∝ T/q, T being the temperature, q the electronic charge, NA and ND are the doping levels of the p and n region respectively, and ni is the intrinsic carrier concentration. In an unbiased p-n junction, the junction current at equilibrium is a. due to diffusion of majority carriers only b. due to diffusion of minority carriers only c. zero, because equal and opposite drift and diffusion currents for electrons and holes cross the junction d. zero, because no charges cross the junction

86.

87.

88.

89.

What is the purpose of impedance matching between the output of previous stage and input of next stage in a cascaded amplifiers a. To achieve high efficiency b. To achieve maximum power transfer c. To achieve reduced distortion d. To achieve reduced noise In a bridge, a.c. to d.c. converter using p-n diodes, if the input voltage is V sin ωt, what is the peak inverse voltage across any diode? a. V b. 2V c. V/2 d. V/ 2 Why is an external pass resistor used in a voltage regulator? a. For short circuit protection b. For increasing the current that regulator can handle c. For increasing the output voltage d. For improving the regulation What is the power factor of a single phase a.c. regulator feeding a resistive load? a. (Per unit power)2 b. (Per unit power)1/2 c.

( Per unit Power )

92.

93.

94.

95.

2

2

( Per unit Power )

1/2

d.

90.

91.

2 When the firing angle α of a single phase fully controlled rectifier feeding constant d.c. current into the load is 300, what is the displacement factor of the rectifier? a. 1 b. 0.5 c.

3

d.

3 /2

For the same voltage output, which one of the following has larger peak inverse voltage of the thyristor? a. Single phase full wave centre tapped circuit b. Single phase full wave bridge circuit c. Three phase full wave cridge circuit

96.

12 of 15 d. Three phase full wave centre tapped circuit In a three phase voltage source inverter operating in square wave mode, the output line voltage is free from a. 3rd harmonic b. 7th harmonic c. 11th harmonic d. 13th harmonic A fully controlled line communtated converter functions as an invertor when firing angle (a) is in the range a. 00 — 90° b. 900 — 180° c. 90° — 1800 only when there is a suitable d.c. source in the load d. 900 — 1800 only when it supplies a back e.m.f. load Which of the following devices should be used as a switch in a low power switched mode power supply (SMPS)? a. GTO b. MOSFET c. TRIAC d. THYRISTOR Assertion (A) : Under V/f control of induction motor, the maximum value of the developed torque remains constant over a wide range of speed in the subsynchronous region. Reason (R) : The magnetic flux is maintained almost constant at the rated value by keeping the ration V/f constant over the considered speed range. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : Bus admittance matrix is a sparse matrix. Reason (R) : In load flow studies, one of the buses is taken as a slack bus. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false

97.

98.

99.

100.

d. A is false but R is true Assertion (A) : Present day, surge diverters use nonlinear resistance elements. Reason (R) : A non-linear resistance element has the property that its resistance increases sharply as the voltage across it increases. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : In JFET, the phenomenon of thermal runaway is not observed around room temperature. Reason (R) : The heat dissipation in the semiconductor increases its temperature which increases the carrier mobility with temperature. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : In a good power supply, the percentage of voltage regulation should be close to zero. Reason (R) : Zero percentage regulation means that there will be no change in output voltage if the load resistance varies between the limits 0 to ∞. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : A clamping network produces an output signal which is a replica of the input signal. Reason (R) : A clamping circuit removes a part of the input signal. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false

101.

102.

103.

104.

13 of 15 d. A is false but R is true Assertion (A) : Stack is a group of memory locations in RAM used for temporary storage of data. Reason (R) : PUSH and POP instructions are used to send and retrieve data from stack. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A) : In frequency division multiplexing (FDM), different carriers are to be generated for different channels. Also, each channel occupies a separate frequency band and different band pass filters are employed. Reason (R) : The non-linearities in various amplifiers of an FDM system do not produce any harmonic distortion and there is no interference within, the channels. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true A loss-less cylindrical rotor synchronous generator is floating on the system bus-bar after being, properly synchronised and is running at no-load. Now, if the prime mover is acting as a mechanical load on the machine, then a. the torque developed by the machine will act in the same direction as the prime-mover torque b. the torque developed by the machine will act in the opposite direction to that of the prime-mover torque c. the machine rotor would fall-back and induced emf would lag behind the terminal voltage d. the machine rotor would overspeed and the induced emf would lead the terminal voltage The resultant flux density in the air gap of a synchronous generator is the lowest during

105.

106.

107.

108.

a. Open circuit b. Solid short circuit c. Full load d. Hald load A 50 kW d.c. shunt motor is loaded to draw rated armature current at any given speed. When driven (i) at half the rated speed by armature voltage control and (ii) at 1.5 times the rated speed by field control, what are the approximate output powers delivered by the motor? a. 25 kW in (1) and 75 kW in (ii) b. 25 kW in (i) and 50 kW in (ii) c. 50 kW in (i) and 75 kW in (ii) d. 50 kW in (i) and’50 kW in (ii) For a constant supply voltage, what are the effects of inserting a series resistance in the field circuit of a d.c. shunt motor, on its speed and torque ? a. Speed will decrease and the torque will decrease b. Speed will increase and the torque will, increase c. Speed will increase and the torque will decrease d. Speed will decrease and the torque will increase Consider the following statements in respect of d.c. generators: 1. Compensating windings are located in teeth cut out in main poles. 2. Compensating windings are series connected so that the armature reaction is aided at any load. 3. Compensating windings are series connected for cancellation of the armature reaction at any load. 4. Compensating windings are shunt connected to aid, the poles at any load. Which of the statements given above are correct? a. 1 and 2 b. 1, 2 and 3 c. 1 and 3 d. 2, 3 and 4 A self-excited d.c. shunt generator, driven by its prime-mover at the rated speed 1ils to build up voltage across its terminals at

109.

14 of 15 no-load. What reason can be assigned for this? a. The field circuit resistance is higher than the critical resistance b. The initial shunt field emf does not assist the residual resistance c. One of the inter-pole connections is reversed d. The brush-axis shifts slightly from the geometrical neutral axis of the machine Wave winding is employed in a d.c. machine of a. high current and low voltage rating b. low current and high voltage rating c. high current and high voltage rating d. low current and low voltage rating

110.

A.

B.

C.

D. An elementary cylindrical machine has one full-pitch coil in the stator, but the rotor may have (i) two poles or (ii) four poles of permanent magnets. The time-varying voltage that could be induced in the stator coil for one rotation of the rotor, while the rotor is revolving at a constant speed are shown iii the figures A, B, C and D above. Select the correct combination from the code given below: 2-pole 4-pole a. A D B b. A c. C D

111.

d. B C What is the form of an air gap flux density waveform of an uncompensated 2-pole d.c. shunt motor at full-load?

a.

116.

b.

c.

112.

113.

114.

115.

d. Which three-phase connection can be used in a transformer to introduce a phase difference of 300 between its output and corresponding input line voltages? a. Star-delta b. Star-star c. Delta-delta d. Delta-zigzag What is the efficiency of an autotransformer in comparison to that of a twowinding transformer of the same rating? a. Slightly less than that of a two-winding transformer b. Same as that of a two-winding transformer c. More than that of a two-winding transformer d. As low as 1/5th of the efficiency of a two-winding transformer A two-winding transformer is converted into an auto-transformer. If we apply additive polarity and subtractive polarity for the connections, then the secondary voltage is 2640 V and 2160 V, respectively. What is the ratio of primary to secondary voltage on the original transformer? a. 66 : 54 b. 54 : 66 c. 10 : 1 d. 1 : 10 Percentage resistance and percentage reactance of a transformer are 1% and 4%,

117.

118.

15 of 15 respectively. What is voltage regulation at power factor 0.8 lagging and 0.8 leading? a. 2.4% and –0.8%, respectively b. 3.2% and —1.6%, respectively c. 3.2 % and —3.2%, respectively d. 4.8% and 1.6%, respectively If P1 and P2 be the iron and copper losses of a transformer at full load, and the maximum efficiency of the transformer is at 75% of the full load, then what is the ratio of P1 and P2 ? a. 9/16 b. 10/16 c. 3/4 d. 3/16 If the iron core of a transformer is replaced by an air core, then the hysteresis losses in the transformer will a. increase b. decrease c. remain unchanged d. become zero The equivalent circuit of a transformer has the leakage reactances X1, X '2 and the magnetising reactance Xm. What is the relationship between their magnitudes? a. X1 >> X '2 >> Xm b. X1 90°, source of e.m.f. in load d. Full-controlled bridge, α < 90°, source of e.m.f. in load A half-controlled bridge converter is operating from an r.m.s. input voltage of 120V. neglecting the voltage drops, what are the mean load voltage at a firing delay angle of 0°and 180°, respectively? a.

120 × 2 2

π

b. 0 and

V and 0

120 × 2 2

π

V

c.

120 2

π

d. 0 and 18.

19.

20.

21.

V and 0

120 2

π

V

For a step-down d.c. chopper operating with discontinuous load current, what is the expression for the load voltage? (K is duty ratio of chopper) a. V0 = Vd.c ×K b. V0 = Vd.c /K c. V0 = Vd.c /(1-K) d. V0 = Vd.c (1-K) An ideal chopper is operating at a frequency of 500 Hz form a 60 V battery input. It is supplying a load having 3 Ω resistance and 9 mH inductance. Assuming the load is shunted by a perfect commutating diode and assuming battery is lossless, what is the mean load current at an on/off ratio of 1/1? a. 10 A b. 15 A c. 20 A d. None of the above The maximum junction-temperature of a transistor is 150 °C and the ambient temperature is 25 °C. If the total thermal impedance is 1 °C/W, what is the maximum power dissipation? a. 1/175 W b. 175 W c. 125 W g d. 1/125 W Match List-I with List-II and select the correct answer using the code given below the lists: List-I (Device) A. Triac B. Reverse conducting thyristor C. Diac List-II (Monolithic construction of) 1. Two thyristors in anti-parallel 2. A thyristor and a diode in anti-parallel 3. Two diodes in anti-parallel Code: A B C

4 of 15

22.

23.

24.

25.

a. 1 2 3 b. 3 2 1 c. 2 3 1 d. 3 1 2 Consider the following statements about analog communication and multiplexing: 1. Noise problem for analog communication has the greatest effect on TDM system. 2. Noise problem for analog communication has the least effect on SDM system. Which of the statements given above is/are correct? a. 1 only b. 2 only c. Both 1 and 2 d. Neither 1 nor 2 Consider the following statements: 1. An active satellite is one carrying a receiver, a transmitter and power supplies. 2. A passive satellite is simply a metalized sphere reflecting radio signals back to the earth. Which of the statements given above is/are correct? a. 1 only b. 2 only c. Both 1 and 2 d. Neither 1 nor 2 If the ASCII character H is sent and the character I is received, what type of error is represented? a. Single bit b. Multiple-bit c. Burst d. Recoverable In coding theory, if

L = average word length of the code word L min = minimum average word length of the code word Then what is the efficiency of source-code (n)? a.

Lmin L

b.

L Lmin

c.

Lmin L

d. 26.

27.

28.

L Lmin

With the increase in the transmission bandwidth, received signal-power in AM and FM will, respectively a. Increase, increase b. Remain same , increase c. Increase, remain same d. Remain same, remain same Match list-I with List-II and select the correct answer using the code given below the lists: List-I (Modulation) A. PSK B. FM C. AM List-II (Detector/Filter) 1. Square-law detector 2. Ratio detector 3. Matched filter Code: A B C a. 3 1 2 b. 3 2 1 c. 2 1 3 d. 2 3 1 Match List-I with List-II and select the correct answer using the code given below the lists: List-I (Characteristic) A. Capture effect is a characteristic of B. Granular noise occurs in C. Guard band is required in List-II (Modulation) 1. FDM 2. PCM 3. FM Code:

29.

30.

31.

32.

33.

34.

A B C a. 3 2 1 b. 3 1 2 c. 1 2 3 d. 1 3 2 Which signaling scheme is most affected by noise? a. ASK b. FSK c. PSK d. QAM What are the three steps in generating PCM in the correct sequence? a. Sampling, quantizing and encoding b. Encoding sampling and quantizing c. Sampling encoding and quantizing d. Quantizing, sampling and encoding In an AM system, for satisfactory operation, carrier frequency must be n times the bandwidth of message-signal. What is the value of n? a. > 2 b. > 5 c. > 10 d. > 50 For an AM signal, the bandwidth is 10 kHz and the highest frequency component present is 750 kHz. What is the carrier frequency used for this AM signal? a. 675 kHz b. 700 kHz c. 705 kHz d. 710 kHz What is the main object of trellis coding? a. To narrow the bandwidth b. To simplify modulation c. To increase the data rate d. To reduce the error rate When zero mean Gaussian noise of variance N is applied to an ideal half-wave rectifier, what is the mean square value of the rectified noise? a. N/4 b. N/2 c. N d. 2N

35.

36.

37.

38.

39.

5 of 15 When TRAP interrupt is triggered in an Intel 8085A, the program control is transferred to which one of the following? a. 0020 H b. 0024 H c. 00 28 H d. 00 2C H The stack pointer of an 8085A microprocessor contains ABCD H. PUSH PSW XTHL PUSH D JMP EC 75 H At the end of the execution of the above instructions, what would be the content of the stack pointer? a. ABCB H b. ABCA H c. ABC9 H d. ABC8 H If the HLT instruction of an Intel 8085A microprocessor is executed a. The microprocessor is disconnected form the system bys till the RESET us pressed b. The microprocessor halts the execution of the program and returns to the monitor c. The microprocessor enters into a HALT state and the buses are tri-stated d. The microprocessor reloads the program counter form the locations 0024 H and 0025 H Consider the following statements: Skewing of rotor slots in a 3 phase induction motor (cage rotor) may 1. Introduce additional leakage reactance 2. Eliminate slot harmonics Which of the statements given above is/are correct? a. 1 only b. 2 only c. Both 1 and 3 d. Neither 1 nor 2 In the equivalent circuit of a double cage induction motor, the two rotor cages can be considered a. To be in parallel b. To be in series-parallel

40.

c. To be in series d. To be in parallel with stator A 3 phase squirrel-cage induction motor is started by means of a star/delta switch. What is the starting current of the motor? a. 3 times the current with direct on line starting 1 b. times the current with direct on line 3 starting c. 1 times the current with direct on 3

line starting d.

41.

42.

43.

44.

3 times the current with direct on line starting Sludge formation in transformer oil is due to which one of the following? a. Ingress of dust particles and moisture in the oil. b. Appearance of small fragments of paper, varnish, cotton and other organic materials in the oil c. Chemical reaction of transformer oil with the insulating materials d. Oxidation of transformer oil A single-phase transformer rated for 220/440 V, 50 Hz. This frequency operation at rated voltage results in which one of the following? a. Increases of both eddy-current and hysteresis losses b. Reduction of both eddy-current and hysteresis losses c. Reduction of hysteresis loss and increase in eddy-current loss d. Increase of hysteresis loss and no change in the eddy-current loss What is the load at which maximum efficiency occurs in case of a 100 kVA transformer with iron loss of 1 kW and full–load copper loss of 2 kW? a. 100 kVA b. 70.7 kVA c. 50.5 kVA d. 25.2 kVA Match list-I with list-II and select the correct answer using the code given below the lists: List-I

45.

46.

47.

48.

6 of 15 (Method of speed control of 3 phase wound-type induction motor) A. Stator voltage control B. Rotor resistance control C. Constant volts/Hz control D. Injection of voltage in rotor circuit List-II (Performance achieved) 1. Both speed and p.f. can be controlled 2. Maximum torque remains constant 3. Starting torque decreases 4. Starting torque decreases Code: A B C D a. 2 1 4 3 b. 4 3 2 1 2 3 4 1 c. 4 1 2 3 d. Cores of large power transformers are made form which one of the following? a. Hot-rolled steel b. Cold-rolled non-grain oriented steel c. Cold-rolled grain oriented steel d. Ferrite A transformer has a percentage resistance of 2% and percentage reactance of 4%. What are its regulations at power factor 0.8 leading, respectively? a. 4% and - 0.8% b. 3.2% and – 1.6% c. 1.6% and – 3.2 % d. 4.8% and – 0.6% The daily energy produced in a thermal power station is 720 MWh at a load factor of 0.6. What is the maximum demand of the station? a. 50 MW b. 30 MW c. 72 MW d. 720 MW Taking the density of water to be 1000 kg/m2, how much power would be developed by a hydroelectric generator unit, assuming 100% efficiency, with 1.0 m head and 1.0 m3/s discharge? a. 2.90 kW b. 4.45 kW c. 9.80 kW

49.

50.

51.

52.

d. 19.60 kW Consider the following statements regarding the nuclear power plans: 1. A thermal rector needs a moderator material 2. In a nuclear reactor, multiplication factor is kept almost equal to one. 3. Nuclear power plants are used as peak load plants only. Which of the statement given above are correct? a. 1, 2 and 3 b. 1 and 2 only c. 2 and 3 only d. 1 and 3 only The full-load copper loss and iron loss of a transformer are 6400 W and 5000 W, respectively. What are the above copper loss and iron loss, respectively at halfload? a. 3200 W, 2500W b. 3200 W, 5000W c. 1600 W, 1250 W d. 1600 W, 5000 W In a 3 phase, 5 kV, 5 MVA systems, what is the base impedance? a. 5 ohms b. 50 ohms c. 500 ohms d. 0.5ohm Match list-I with list-II and select the correct answer using the code given below the lists: List-I A. Transient stability improvement B. Economic dispatch C. Load frequency control D. Dynamic stability List-II 1. Incremental transmission loss 2. Area control error 3. Power system stabilizers 4. Turbine fast valuing Code: A B C D a. 2 3 4 1 4 1 2 3 b. 2 1 4 3 c.

53.

54.

7 of 15 d. 4 3 2 1 Consider the following statements: 1. Equivalent- T circuit of a long line is preferred to equivalent - π circuit. 2. The nature of reactive power compensation is different for peak load and off-peak load conditions. 3. Ferranti effect is significant only on medium and long lines. Which of the statements given above are correct? a. 1 and 2 only b. 1 and 3 only c. 2 and 3 only d. 1, 2 and 3 For an extra-high voltage overhead transmission line, four conductors are used per phase (in a bundle) at the corners of a square of sides meter. The GMR (geometric mean radius) of each conductor is r m meter. What is the GMR of the bundle conductor? a. (r1m × s2× 2 s ) 1/4 b.

(rm' × s3 )

c.

(rm' × 3s3 )

1/4

⎡ d. ⎢ rm' × ⎣⎢ 55.

56.

1/4

(

3⎤ 2s ⎥ ⎦⎥

)

1/4

When is the Ferranti effect on long overhead lines experienced? a. The line is lightly loaded b. The line is heavily loaded c. The line is fully loaded d. The power factor is unity What is the surge impedance loading of a lossless 400 kV, 3-phase, 50Hz overhead line of average of surge impedance of 400 ohms? a. 400 MW b. 400 3 MW c. 400/ 3 MW d. 400 kW

57.

58.

59.

60.

61.

The figure given above shows a schematic arrangement of a Distance Relay provided with a ‘Replica Impedance’ Zr. The CT ratio = I/v and VT ratio = V/v. When a fault occurs on the line being protected, when would the relay operate? a. Zr > Z b. Zr < Z c. Zr > Z. I/i d. Zr > Z. V/v A 50 Hz, 3-phase synchronous generator has inductance per phase of 15 mH. The capacitance of generator and circuit breaker is 0.002 μ F . What is its natural frequency of oscillation? a. 29 kHz b. 2.9 kHz c. 290 kHz d. 29 MHz Consider the following statements regarding HVDC power transmission: 1. The modern HVDC systems use 12pulse converters. 2. DC systems never use ground or sea return. 3. Most of present-day d.c. schemes are two-terminal links. Which of the statements given above is/are correct? a. 1, 2 and 3 b. 1 only c. 2 and 3 only d. 1 and 3 only Two generating stations connected to a load centre having capacity of 50 MVA and 75 MVA deliver 100 MW to the load. The incremental cost of plant 1 is 15 + 0.15P1 and that of the plant 2 is 18 + 0.15P2. What are the value of P1 and P2, respectively? a. 60 MW and 40 MW b. 50 MW each c. 72 MW and 28 MW d. 30 MW and 70 MW A two-quadrant d.c. to d.c. chopper can operate with which of the following load conditions? 1. +ve voltage, +ve current 2. –ve voltage, +ve current

8 of 15 3. –ve voltage, -ve current 4. +ve voltage, -ve current Select the correct answer using the code given below: a. 1 only b. 1 and 2 only c. 1 and 4 only d. 3 and 4 only 62.

For the circuit shown in Fig. A, the V-I (voltage-current) characteristic of the circuit using ideal components is given by curve a in Fig. B. Which curve in Fig. B represents the V-I characteristic for the circuit shown in Fig C? a. Curve a b. Curve b c. Curve c d. Curve d 63.

What is the peak current through the resistor in the circuit given above assuming the diode to be ideal?

64.

a. 4 mA b. 8 mA c. 12 mA d. 16 mA For a rectifier circuit, percentage voltage regulation is equal to which one of the following? Vno load − V full load ×100 a. Vno load b. c. d.

65.

66.

67.

68.

Vno load − V full load V full load Vno load − V full load Vno load + V full load V full load Vno load

×100

d. T1.

69.

70.

×100

× 100

A single-phase current source inverter is connected with capacitive load only. The waveform of the output voltage across the capacitor for constant source current will be a. Sine wave b. Square wave c. Triangular wave d. Step function A modern power semiconductor device that combines the characteristics of BJT and MOSFET is a. GTO b. FCT c. IGBT d. MCT A digital communication system uses 8PSK modulation and transmits 3600 bps. What is the symbol rate? a. 10800 symbols/sec b. 450 symbols/sec c. 28800 symbols/sec d. 1200 symbols/sec If two resistors of values R1 and R2 (at temperatures T1 and T2) are connected in series to form a white noise source, the equivalent noise temperature is R1T1 + R2T2 a. R1 + R2 b.

c. T1 + T2

R1T1 − R2T2 R1 + R2

71.

72.

73.

74.

9 of 15

R1 R + T2 . 2 R2 R1

The contents of Program Counter (PC), when the microprocessor is reading from 2FFF H memory location, will be a. 2FFE H b. 2FFF H c. 3000 H d. 3001 H Carry flag is not affected after the execution of a. ADD B b. SBB B c. INR B d. ORA B Which one is the indirect addressing mode in the following instructions? a. LXIH 2050 H b. MOV A, B c. LDAX B d. LDA 2050 H An 8254 programmable interval timer consists of independent 16-bit programmable counters. This number is a. 2 b. 3 c. 4 d. 5 What are the advantages of switching power supplies over linear power supplies? 1. The devices operate in linear/active region. 2. The devices operate as switches. 3. Power losses are less. Select the correct answer using the code given below: a. 1 and 3 only b. 2 and 3 only c. 1 and 2 only d. 1, 2 and 3 Assertion (A): A d.c. motor draws high current at the time of starting. Reason (R): While starting a d.c. motor, it takes some time to develop a non-zero value of back e.m.f. a. Both A and R are individually true and R is the correct explanation of A

75.

76.

77.

78.

b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): For a 3-phase alternator operating on leading p.f at full load, the terminal voltage may be more than the noload induced e.m.f Reason (R): At leading power factor, the effect of armature reaction is demagnetizing. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): AC armature windings are short chorded by selecting value of coil span more than the pole pitch. Reason (R): Short chording is done to eliminate harmonics in the induced e.m.f. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): The leakage reactance of a 3-phase induction motor should be small. Reason (R): A small value of leakage reactance will increase the maximum power output of motor. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Both the efficiency and regulation of a 3-winding ideal transformer are 100%. Reason (R): The flux leakage and the magnetic reluctance of the magnetic core in an ideal transformer are zero. Moreover, losses are absent in ideal transformers. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A

79.

80.

81.

82.

10 of 15 c. A is true but R is false d. A is false but R is true Assertion (A): The ‘short-circuit capacity’ of a bus in a large power grid is defined as the product of the pre-fault voltage and the 3-phase fault current at a point very close to the bus. Reason (R): The larger the short-circuit capacity, the large would be the equivalent source impedance at the bus. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): It is not possible to design a current source using operational amplifier. Reason (R): Operational amplifier is a voltage controlled voltage source. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Each memory cell of a DRAM requires refreshing every 2, 4 or 8 ms or its data will be lost. Reason (R): DRAM stores 1s and 0s as charges on a small MOS capacitor which has tendency to leak off charges after a period of time. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Assertion (A): Bandwidth of anglemodulated signal is infinite. Reason (R): Angle modulation of a carrier result in the generation of an infinite number of an infinite number of sidebands. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true

83.

84.

85.

86.

Assertion (A): In television transmission, interlaced scanning is used. Reason (R): Interlaced scanning provides increased picture brightness. a. Both A and R are individually true and R is the correct explanation of A b. Both A and R are individually true but R is not the correct explanation of A c. A is true but R is false d. A is false but R is true Consider the following statements in Johnson counter: 1. A MOD–6 Johnson counter requires 3 FFs. 2. Johnson counter requires decoding gates. 3. To decode each count, one logic gate is used. Each gate requires only two inputs regardless of the number of FFs. Which of the statements given above are correct? a. 1 and 2 only b. 2 and 3 only c. 1 and 3 only d. 1, 2 and 3 What is the simplified form of the Boolean expression T = ( X + Y )( X + Y )( X + Y ) ?

87.

88.

The Boolean expression A.B + A.B is logically equivalent to which of the following? 1. ( A + B ).( A + B) 2. ( A + B ).( A + B) 3. ( A.B + A.B) 4. ( A.B ).( A.B ) Select the correct answer using the code given below: a. 1 and 2 only b. 2 and 3 only c. 1 and 3 only d. None of the above

89.

a. XY b. XY c. XY d. XY Match List–I with List-II and select the correct answer using the code given below the Lists: List-I (Expression – I)

In the given circuit, the output Y equals which one of the following? a. A + B b. AB + AB c. AB d. A + B

A. ABC + ABC + ABC B. ABC + ABC + BC

11 of 15 c. A2, B3, C4, D1 d. A4, B1, C2, D3 The AND function can be realized by using only n number of NOR gates. What in n equal to? a. 2 b. 3 c. 4 d. 5

90.

C. ABC + ABC + ABC + ABC D. AB + AB + ABC List-II (Expression – II) 1. A + BC 2. A( B + C ) 3. BC 4. AB + BC + AC Codes: a. A2, B1, C4, D3 b. A4, B3, C2, D1

In the circuit given above, the Zener diode D1 has a reverse breakdown voltage of 100 V and reverse saturation current of 25 μ A. The corresponding values for D2 are

50 V and 50 μ A. What is the current in the circuit? a. 25 μ A anticlockwise b. 25 μ A clockwise c. 50 μ A anticlockwise d. 50 μ A clockwise 91. 94.

What is the output voltage vo of the given circuit? a. −5va + 2.5vb b. −5va + 3vb

95.

c. −2.5va + 2.5vb d. −2.5va + 3vb 92.

96. Consider the following statements in respect of the Wien bridge oscillator shown in the figure above: 1. For R = 1 kiloohm ⎛1⎞ C = ⎜⎜ ⎟⎟⎟ μ F , f = 1kHz ⎜⎝ 2π ⎠

b. ω0 (1 + A0β )

2. For R = 3 kiloohms ⎛ 1 ⎞⎟ C = ⎜⎜ μ F , f = 3kHz ⎜⎝18π ⎠⎟⎟

93.

Which of the statements given above is/are correct? a. 1 only b. 2 only c. Both 1 and 2 d. Neither 1 nor 2 Consider the following statements: 1. Wien bridge oscillator is suitable for generating 1 kHz.

12 of 15 2. Colpitts oscillator is suitable for generating 1 MHz. Which of the statements given above is/are correct? a. 1 only b. 2 only c. Both 1 and 2 d. Neither 1 nor 2 A sinusoidal signal of 100 Hz is applied to an amplifier. The output current is i0 = 20sin(628t ) + 2sin(1256t ) +1sin(1256t ) What is the approximate percentage increase in power due to distortion? a. 1.15 b. 1.25 c. 1.30 d. 1.50 A resistance Rf is connected across the collector and base of a BJT amplifier of gain –A(A>0). The input impedance of the amplifier will consist of transistor internal resistance rb ' e shunted by which one of the following? a. Rf (1+A) b. Rf (1-A) c. Rf /(1+A) d. Rf /(1-A) A negative feedback amplifier with open− A0 A0 > 0 and feedback loop gain ω 1+ j ω0 factor β (> 0) will have a 3 dB cut-off at what frequency? a. ω0 A0 β c. ω0 / (1 + A0 β ) d. ω0 / (1− A0 β )

97.

101.

98.

What is the transistor combination shown in the figure given above? a. A Darlington pair b. A complementary pair c. It effectively acts as a single p-n-p transistor d. If effectively acts as a single n-p-n transistor What is the effect of cascading the amplifier stages? a. To increase the voltage gain and increase the bandwidth b. To increase the voltage gain and reduce the bandwidth c. To decrease the voltage gain and increase the bandwidth d. To decrease the voltage gain and reduce the bandwidth

2. ∝ Eb I a 3. ∝ Eb / φ 4. ∝ I aφ

102.

99. 103.

100.

The graph shown above represents which characteristic of a d.c. shunt generator? a. Internal characteristic b. External characteristic c. Open-circuit characteristic d. Magnetic characteristic When is the mechanical power developed by a d.c. motor maximum? a. Back e.m.f is equal to applied voltage b. Back e.m.f is equal to zero c. Back e.m.f is equal to half the applied voltage d. None of the above

13 of 15 Match List-I with List-II and select the correct answer using the code given below the Lists: List – I (DC machine quantity) A. Developed power B. Torque C. Generated e.m.f. D. Speed List – II (Relation) 1. ∝ N φ

Codes: a. A2, B4, C1, D3 b. A3, B1, C4, D2 c. A2, B1, C4, D3 d. A3, B4, C1, D2 A shunt generator has a critical field resistance of 200 Ω at a speed of 800 r.p.m. If the speed of the generator is increased to 1000 r.p.m., what is the change in the critical field resistance of the generator? a. Decreases to 160 Ω b. Remains the same at 200 Ω c. Increases to 250 Ω d. Increases to 312.5 Ω Which one of the following curves represents the speed-torque characteristic of a d.c. series motor? a.

b.

c.

d.

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Match List – I with List – II in respect of synchronous machines and select the correct answer using the code given below the List: List-I (Machine characteristic) A. Open-circuit characteristic B. V-curve C. Internal Characteristic D. Inverted V-curve List-II (Quantity) 1. p.f. vs. If 2. Ea vs. Ia 3. Eg vs. If 4. Ia vs. If Code: a. A3, B1, C2, D4 b. A2, B4, C3, D1 c. A3, B4, C2, D1 d. A2, B1, C3, D4 Which of the following conditions are to be satisfied for proper synchronization of alternators? 1. Equal terminal voltage 2. Same frequency 3. Same phase sequence 4. Same kVA rating 5. Same phase displacement Select the correct answer using the code given below: a. 1, 3, and 4 only b. 1, 2, 4 and 5 only c. 2, 3, 4 and 5 only d. 1, 2, 3 and 5 only If the excitation of a 3-phase alternator operating on infinite bus bars is changed, which one of the following shall alter? a. Active power of machine b. Reactive power of machine c. Terminal voltage of machine d. Frequency of machine The stator of a 3-phase, 6-pole a.c. machine has 45 slots. The stator winding has 45 coils with a coil span of 6 slots.

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14 of 15 What type of winding will be selected for this machine? a. Double-layer, fractional slot, shortpitched winding b. Single-layer, fractional slot, shortpitched winding c. Single-layer, integral slot, full-pitch winding d. Double-layer, fractional slot, full-pitch winding When are eddy-current losses in a transformer reduced? a. If laminations are thick b. If the number of turns in primary winding is reduced c. If the number of turns in secondary winding is reduced d. If laminations are thin Why is a centrifugal switch used in a single-phase induction motor? a. To protect the motor from overloading b. To improve the starting performance of the motor c. To cut off the starting winding at an appropriate instant d. To cut in the capacitor during running conditions What is the operating slip of a 400 V, 50 Hz, 6-pole, 3-phase induction motor, while the speed is 936 r.p.m. with a 400 V, 45 Hz, 3-phase supply? a. 0.036 b. 0.064 c. 0.025 d. 0.075 A 3-phase slip-ring induction motor having negligible stator impedance drives a constant torque load. If an additional resistance is included in the rotor circuit, what does the motor experience? a. Increase in both the stator current and the slip b. No change in the stator current and increase in the slip c. Increase in the stator current and no change in the slip d. Decrease in the stator current and increase in the slip Breakdown torque in a 3-phase induction motor of negligible stator impedance is

113.

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a. Directly proportional to rotor resistance b. Inversely proportional to rotor resistance c. Directly proportional to rotor leakage reactance d. Inversely proportional to rotor leakage reactance Match List – I with List – II and select the correct answer using the code given below the Lists: List-I (Controller) A. Chopper-controlled resistance in the rotor B. Sub-synchronous converter-cascade in the rotor circuit of an induction motor C. 3-phase a.c. voltage controller D. Cyoloconverter List-II (Type of load) 1. Very low speed, high-power reversible drive 2. Centrifuges in sugar industry 3. Blowers and compressors 4. Loads requiring good starting performance Code: a. A3, B4, C2, D1 b. A3, B4, B1, D2 c. A4, B3, C1, D2 d. A4, B3, C2, D1 A cyclo-converter-fed induction motor drive is most suitable for which one of the following? a. Compressor drive b. Machine tool drive c. Paper mill drive d. Cement mill drive A large d.c. motor is required to control the speed of blower from a 3-phase a.c. source. What is the most suitable a.c. to d.c. converter? a. 3-phase fully controlled bridge converter b. 3-phase fully controlled bridge converter with free wheeling diode c. 3-phase half-controlled bridge converter

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15 of 15 d. A pair of 3-phase converter in sequence control A single-phase full-bridge inverter is connected to a load of 2.4 Ω . The d.c. input voltage is 48 V. What is the r.m.s. output at fundamental frequency? 4× 48 a. V 2π 2× 48 V b. 2π 4× 48 c. V π 2× 48 V d. π A buck regulator has an input voltage of 12 V and the required output voltage is 5 V. What is the duty cycle of the regulator? a. 5/12 b. 12/5 c. 5/2 d. 6 A balanced 3-phase induction motor runs at slip S. If ω s is its synchronous speed, what is the relative speed between the stator m.m.f. and rotor m.m.f.? a. S ω s b. (1− S )ω s c. ω s

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d. Zero Maximum efficiency of modern coal-fired steam-raising thermal power plants is restricted to about 0.35 (a low value), mainly because of a. Low alternator efficiency b. High energy loss in boilers c. Low steam turbine mechanical efficiency d. High energy loss from turbine exhaust to condenser Mho relay is usually employed for the protection of a. Short lines only b. Medium lines only c. Long lines only d. Any line

I.E.S- (OBJ) 2008

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GENERAL ABILITY TEST PART-A SYNONYMS

ANTONYMS

Directions (For the 9 items which follow):

Directions (For the 7 items which follow):

Each of the following nine items consists of a word or a group of words in capital letters, followed by four words or groups of words. Select the word or group of words that is most similar in meaning to the word or group of words in capital letters.

Each of the following seven items consists of a word in capital letters, followed by four words or groups of words. Select the word or group of words that is furthest in meaning to the word in capital letters.

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BEAVER AWAY a. To waste away b. To sleep for long hours c. To work hard d. To steal something BADGER a. To ricochet b. To err c. To apologize d. To pester persistently SWISH a. False b. Fashionable c. Annulment d. Rapid SURREPTITIOUS a. To be impatient b. Susceptible c. Supportive d. To act stealthily SURROGATE a. Surpassable b. Substitute c. Surfeit d. Surveillant UP-THE CREEK a. To get lot of money b. In dire difficulties c. To be very successful d. To achieve one’s aim by deceit CAVEAT a. Award b. Controversy c. Warning d. Graphic NIP AND TUCK a. Close competition b. Heavy rain c. Fierce attack d. Mixture COMEUPPANCE a. Sudden arrival b. Parity c. Paradox d. Retribution

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SALACIOUS a. Decent b. Satisfying c. Preciptious d. Fortifying SEDULOUS a. Lack of emotions b. Lack of steady effort c. Affluent d. Modest SWINGEINE a. Dull b. Meagre c. Disrepute d. Proportionate TEDIUM a. Appreciation b. Fixation c. Neutrability d. Liveliness TENDENTIOUS a. Impartial b. Calm c. Supplementary d. Super-duper TEMERITY a. Humourous b. Hybrid c. Humility d. Humiliation CAPRICE a. Excuse b. Steady behaviour c. Accusation d. Exhortation

Directions (For the 5 items which follow): In each of the following five items, a related pair of words (in capital letters) is followed by four pairs of words. Select the pair that best expresses a relationship similar to that expressed in the original pair (in capital letters).

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CALLOW : MATURITY a. Eager : Anxiety b. Incipient : Fruition

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c. Apathetic : Disinterest d. Exposure : Weathering DAMPEN : ENTHUSIASM a. Moisten : Throat b. Test : Commitment c. Reverse: Direction d. Mute : Sound RUFFLE : COMPOSURE a. Flourish : Prosperity b. Adjust : Balance c. Upset : Equilibrium d. Chaff : Wheat LATENT : MANIFESTATION a. Dormant : Awakening b. Patent : Appearance c. Redoubtable : Impress d. Aggrieved : Distress CELERITY : SNAIL a. Indolence : Sloth b. Humility : Peacock c. Nervous : Energy d. Emulation : Rivalry

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SPOTTING ERRORS Directions (For the 6 items which follow) : (i)

In this section, a number of sentences are given. The sentences are underlined in three separate parts and each one is labeled (a), (b) and (c). Read each sentence to find out whether there is an error in any underlined part. No sentence has more than one error. When you find an error in any one of the underlined parts (a), (b) or (c), indicate your response on the separate Answer Sheet at the approximate space. You may feel that there is no error in a sentence. In that case letter (d) will signify a ‘No error’ response. (ii) You are to indicate only one response for each item in your Answer Sheet. (If you indicate more than one response, your answer will be considered wrong) Errors may be in grammar, word usage or idioms. There may be a word missing or there may be a word which should be removed. (iii) You are not required to correct the error. You are required only to indicate your response on the Answer Sheet. Example ‘P’ and ‘Q’ have been solved you for. (EXAMPLES) P. The young child singed (a) (b) A very sweet song. No error (c) (d) Explanation: In item P, the word ‘signed’ in wrong. The letter under this part is (b); se (b) is the correct answer. Similarly, for item Q, (d) is the correct answer, as the sentence does not certain any error.

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There were gapes of horror (a) form the spectators as (b) the performer fell from the tightrope (c) No error (d) She gazed at me (a) in misbelief when

27.

(b) I told her the news (c) No error (d) Acting from inside information (a) the police were able to arrest the gang (b) before the robbery occurred (c) No error (d) Amit did not have a girl-friend (a) till he was 21, but now (b) he is making up at the lost time (c) No error (d) She wanted to be an actress (a) but her father soon (b) nipped that idea in the bud (c) No error (d) Captain’s language was uncompromising (a) he told junior officers their work (b) must improve or they would be fired (c) No error (d) ORDERING OF SENTENCES

Directions (For the 10 items which follow): In the following items, each passage consists of six sentences. The first sentence (S1) and final sentence (S6) are given in the beginning. The middle four sentences in each have been removed and jumbled up. These are labeled P, Q, R and S. You are required to find out the correct sequence of the four sentences and mark accordingly on the Answer Sheet. Example ‘X’ has been solved for you.

(EXAMPLE) X.

S1 : S6 : P:

There was a boy named Jack At least she turned him out of the house So the mother asked him to find work

Q: R: S:

They were very poor he lived with his mother But Jack refused to work

Which one of the following is the correct sequence? (a) R–Q–P-S (b) P–Q–R-S

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Q–P–R-S R–P–S-Q

Explanation: The correct sequence in this example is R-Q-PS, which is marked by (a). Therefore, (a) is the correct answer.

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S1 : The first aeroplanes were fragile and clumsy. S6 : In those days people considered flight in an aeroplane to be a miracle P : When they took off they would not fly very high Q : They also broke down frequently R: It was difficult for them to take off S : They flew slowly and only in the vicinity of the airfield Which one of the following is the correct sequence? a. R – P – S – Q b. S – Q – R – P c. R – Q – S – P d. S – P – R – Q S1 : Lions usually live in a family parties called ‘prides’. S6 : They actack man only when they are wounded or otherwise aroused. P : Wild lions are not normally a menance to man. Q : A pride is commonly made up of a lion, two lionesses and cubs. R : Sometimes pigs and other animals are also killed by them. S : They usually prey on zebras and antelopes. Which one of the following is the correct sequence? a. P – S – R – Q b. Q – R – S - P c. P – R – S – Q d. Q – S – R – P S1 : Not long age television was a rarity. S6: Only a few people understand the technology behind it. P: It has become a means of entertainment and information. Q: Yet nowadays there is one in virtually every home. R: But most of us do not know much about how an image appears on the television screen S: We have grown used to it. Which one of the following is the correct sequence? a. P – R – Q – S b. Q – S – P – R c. P – S– Q – R d. Q – R – P – S S1: I have know in my own life, in my own experience, people who were hating one another on account of their religious views.

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S6: We are the inheritors of a great world heritage. P: They try to find out whatever is of value in them. Q: You will find that other religions are studies with sympathy and respect by those who do not adhere to them R: All that has changed today. S: The classics of the whole world form the classics of every human being. Which one of the following is the correct sequence? a. P – S – R – Q b. R – Q – P – S c. P – Q – R – S d. R – S – P – Q S1: Javert was a strong, upright and just man. S6: So he took the only way out for him-he killed himself. P: But now his life was turned upside down. Q: It was his safe world of rules. R: He would help no one, and he helped no one. S: He did not want favours from a thief. Which one of the following is the correct sequence? a. Q – P –S – R b. S – R –Q – P c. Q – R –S – P d. S – P – Q – R S1: Nowadays we pay a great deal of attention to pure air, open windows and garden cities. S6: Pasteurised milk is milk which has been treated in this way. P: Another useful discovery of Pasteur’s was the process, now called, pasteurization. Q: Pasteur was one of the first to show how necessary all these are if we are to fight against germs and disease. R: Pasteur helped them by showing that by heating win or milk to a temperature of 60 degree Centrigrade, the germs were made harmless. S: Some wine-growers were troubled by a germ which has turned their win sour. Which one of the following is the correct sequence? a. R – S –P – Q b. Q– P – S – R c. R – P – S – Q d. Q– S – P – R S1: Scientist have found that any train running on wheels cannot go faster than 300 kilometres an hour. S6: Japanese engineers are, therefore, planning another kind of train, a magnetic train without, wheels, which would also float above the ground.

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P: One way of building such trains has already been tried out Q: If we want trains which can go still faster we must build them without wheels. R: But it would not be possible to run them on the Tokaido line because in same tunnels there would not be enough air to support them S: Here, the whole train floats above the ground on top of a cushion of air created by powerful fans. Which one of the following is the correct sequence? a. Q–P–S–R b. S–R–Q–P c. Q–R–S–P d. S–P–Q–R S1: Newspapers are the cheapest medium of information today. S6: Consequently, 50 percent of our population is denied across to information vital for the functionaries of a democracy. P: If you cannot buy a paper, you can go to a public library. Q: And yet newspapers do not reach nearly fifty percent of our population. R: They are also easily available to everybody S: It is because people are illiterate. Which one of the following is the correct sequence? a. R–S–Q–P b. Q–P–R–S c. R–P–Q–S d. Q–S–R–P S1: Social isolation, overcrowding, the competitiveness of our society and several other factors are responsible for stress. S6: Yet some other get totally depressed and often much worried. P: In England we refer to competition in society as the ‘rat-race’. Q: All of us react to that rat-race in different ways. R: But some of us get very much tried and bored every easily. S: The pressures on all of us are very great because speed and competition have become part of everyday life. Which one of the following is the correct sequence? a. R–P–Q–S b. S–Q–P–R c. R–Q–P–S d. S–P–Q–R S1: It is true that a few women have opportunities to work outside the home. S6: If women stop doing this work there would be havoc in the public life. P: Women do much work all the time within the house.

Q: This work could be termed as socially productive labour. R: It consists of cooking, washing, cleaning, fetching fuel and water etc. S: This work is crucial to the survival of society. Which one of the following is the correct sequence? a. P–Q–R–S b. R–S–P–Q c. P–S–R–Q d. R–Q–P–S ORDERING OF WORDS IN A SENTENCE Direction (For the 10 items which follow) In the following item, some parts of the sentence have been jumbled up. You are required to rearrange these parts which are labeled P, Q, R and S to produce the correct sequence. Choose the proper sequence and marks in your Answer Sheet accordingly. Example ‘Z’ has been solved for you. (EXAMPLE) Z. It is well-known that it very bad the effect P Q of cinema on children R S Which one of the following is the correct sequence? (a) P–S–R–Q (b) S-P-Q-R (c) S-R-P-Q (d) Q-S-R-P Explanation: The proper way of writing the sentence is “It is well-known that the effect of cinema on children is very bad.” This is indicated by the sequence P-S-R-Q and so (a) is the correct answer.

38.

Life comes Awed by all the things that their words can do with computer and gadgets P who can get anything done by clinking a few buttons

Q

39.

a full circle when some technologically challenged mothers R begin to believe that their child is a super-kid in the digital world S Which one of the following is the correct sequence? a. R–P–Q–S b. P–R–Q–S c. R–P–S–Q d. P–R–S–Q Unaware Reading other periodicals and publication P ourselves with merely Q of the need to build R

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the intellect we tend to entertain S Which one of the following is the correct sequence? a. Q–P–R–S b. R–S–Q–P c. Q–S–R–P d. R–P–Q–S Loss of employment in a country like India where P is no social security net to fall back on Q most people are still poor and there R or livelihood can be really injurious S Which one of the following is the correct sequence? a. S–R–P–Q b. Q–P–R–S c. Q–R–P–S d. S–P–R–Q Many people organized their energies around a goal P but simply because they have never Q or brains or even courage R fail in life not for lack of ability S Which one of the following is the correct sequence? a. P–Q–R–S b. S–R–Q–P c. P–R–Q–P d. S–Q–R–P Being to a viewing point a higher more expansive place P to move from a point of view Q willing to change allows you R from which you can seen both sides S Which one of the following is the correct sequence? a. R–Q–P–S b. Q–R–P–S c. Q–R–S–P d. R–Q–S–P Yet one area to players who have violated the spirit of the game P

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in which Indian Cricket administration should definitely Q denying the benefits of Indian corporate sponsorship R use its financial clout is in S Which one of the following is the correct sequence? a. R–P–Q–S b. Q–S–R–P c. R–S–Q–P d. Q–P–R–S While improvements have definitely helped climbers now carry lighter oxygen bottles P in technology over the years Q made of titanium and get regular weather updates R through satellite phones the route to Mt. Everest remains treacherous as ever S Which one of the following is the correct sequence? a. Q–P–R–S b. S–R–P–Q c. Q–R–P–S d. S–P–R–Q Life the number of breaths you take P that take your breath away Q is not measured by R but by the moments S Which one of the following is the correct sequence? a. Q–P–S–R b. R–S–P–Q c. Q–S–P–R d. R–P–S–Q The greatest miss it but that it is too P danger for most of us Q is not that our aim is too high and we R low and we reach it S Which one of the following is the correct sequence? a. Q–S–P–R

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b. P–R–Q–S c. Q–R–P–S d. P–S–Q–R The fundamental but an institutional framework that lays down P and cannot be trampled on by the ruling government Q the rights of the people and rules of political engagement R mark of a democracy is not elections S Which one of the following is the correct sequence? a. S–P–Q–R b. P–S–R–Q c. P–S–Q–R d. S–P–R–Q

COMPREHENSION Directions (For the 13 items which follow): In this section, you have three short passages. After each passage, you will find several questions based on the passage. First, read and passage and then answer the questions based on it. You are required to select your answers based on the contents of the passage and opinion of the author only.

peace”, which is response (b). So (b) is the correct answer. PASSAGE I J.K Galbraith has described the current inflation as a “revolt of the rich against the poor”. Richard Parker supports this view with the claim that it is the richest people that benefit by inflation: while the rest, especially the poorest, suffer in proportion to their relative property. On the other hand, a 1979 study published by the Brookings Institute indicates that the lower classes are generally benefited by inflation, while the upper classes lose. The confusion over who suffers from inflation is extended to other questions such as the major causes of inflation. In addition to the proponents of the demand theory, there are many who doubt whether inflation is essentially an economic problem at all. Konard Kellen holds that inflation is not an economic problem but a psychological one. Paul Samuelson cites a social factor, the evaluation of a more humane society, as a root cause of inflation.

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Example ‘T’ and ‘J” are solved for you PASSAGE (EXAMPLE) In our approach to life, be it pragmatic or otherwise, a basic fact that confronts us squarely and unmistakable is the desire for peace, security and happiness. Different forms of life at different levels of existence make up the teeming denizens of this earth of ours. And, no matter whether they belong to the higher groups such as human beings or to the lower groups and as animals, all beings primarily seek peace, comfort and security. Life is as dear to a mute creature as it is to a man. Even the lowliest insect strives for protection against dangers that threaten its life. Just as each one of us wants to live and not to die, so do all other creature. I.

J.

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The author’s remains point is that (a) different forms of life are found on earth (b) different levels of existence are possible in nature (c) peace and security are the chief goals of all living beings (d) even the weakest creature struggles to preserve its life Which one of the following assumptions or steps is essential in developing the author’s position? (a) All forms of life have a single over-riding goal (b) The will to survive of a creature is identified with a desire of peace (c) All beings are divided into higher and lower groups (d) A parallel is drawn between happiness and life, and pain and death.

Explanation: I. The idea which represents the author’s main point is “peace and security are the chief goals of all living being”, which is response (c). So (c) is the correct answer. J. The best assumption underlying the passage in “The will to survive of a creature is identified with a desire for

What does the author believe? a. Only the rich suffer from inflation b. Only the poor suffer from inflation c. Both the rich and the poor suffer from inflation d. It is debatable as to who suffers from inflation From the passage, which one of the following may be inferred? a. The effect of inflation can be studied with scientific precision b. The effect of inflation cannot be studied with scientific precision c. Economists are biased towards the rich or the poor d. The effect of inflation varies from place to place, and people to people On the basis of the information given in the passage, what are the causes of inflation? a. Essentially economic b. Essentially psychological c. Essentially social d. Highly controversial How des the author write? a. Objectively b. Critically c. Sympathetically d. Persuasively PASSAGE II

Work itself is a very important factor in motivating a person. A person tends to perform a task more enthusiastically if that work affords more satisfaction than the other work. A person’s satisfaction out of work is more is it is more need satisfying. A man seeks something from work and if he gets more satisfaction from a particular work he will be prone to do that work better or harder. There are incentives for work; these can be financial or non-financial. People like missionaries and some scientists do not work basically for material gains as such. A person wants to do a work which is personally meaningful.

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Which one of the following is correct? a. Work is the most important factor by which a person is motivated.

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b. Work is the least important factor that motivates a person c. Among the several factors that motivate a person, work is an important one. d. Nothing can motivate a person who does not have some permanent work. Which one of the following is correct? A person’s work satisfaction depends on a. the money and other benefits he receives from work b. the need satisfying nature of the work he does c. the physical environment in which he works d. the personal relationship he establishes with his colleagues and superiors Which one of the following is correct? If, a person get more satisfaction from a particular work, he will a. stick on the that work for every b. certainly achieve mastery over that work soon c. slowly develop a taste for that work d. do that work in a better and harder manure Which one of the following is correct? Both the scientists and the missionaries work a. because of the incentives given to them b. without hopping for any material gain c. without receiving any material gain d. because they want to be appreciated Which one of the following is correct? Every person wants to have a work which a. helps him to get involved meaningfully b. helps him to earn substantially c. is pleasant and easy d. can be finished quickly

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PASSAGE III In our country there is very little popular writing on science. Those who write are writing for other scientists. The newspapers these days devote a little more space then before for scientific topics but they appear to be rather ill-digested knowledge not written in simple readable language. So if we are to bridge this gap and disseminate scientific knowledge and promote scientific temper, it has become necessary for some of the scientists to turn to popularization. Today we have almost compulsion for doing this if we are to convey to the people the meaning and relevance of the pursuit of science. It is time same scientists enters the field of scientific journalism.

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What does the passage suggest? a. The author is fully satisfied with the role of newspapers in promoting popular writing on science. b. The author is totally dissatisfied with the role of newspapers in promoting popular writing on science. c. The author appreciates the readiness of newspapers to allow more space than before to writings on science.

d. The author condemns the attitude displayed by newspapers in the matter of promoting popular writing on science. Which one of the following is correct? Popular writing on science in our country appears to be a. not properly digested and easily comprehensible b. extremely restricted in outlook c. very lucid, intelligible and self explanatory d. based on obsolete knowledge of the topics chosen Which one of the following is correct? The propose of promoting popular scientific writing in newspapers is a. to attract more people to the study of science b. to spread scientific knowledge and encourage scientific temper among the common people c. to give the people information about modern scientific inventions d. to help the newspapers to increase their circulation among the students of science The author wants some of the scientists “to turn to popularization”. What does that imply? a. The scientists should go round and country and explain to the people the various achievements of science b. The scientists should make use of the television and radio to spread the message of science among the common people c. The scientists should write in newspapers about the various aspects of science in easily understandable language. d. The scientists should seek the help of social organizations to spread scientific knowledge among the common people. PART-B

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The deficiency of which one of the following leads to anemia? a. Ascorbic acid b. Citirc acid c. Folic acid d. Nicotinic acid The highly fatal disease of Rabies is caused by which one of the following? a. Virus b. Bacteria c. Protozoan d. Nematode worm How in jasmine plant propagated? a. Grafting b. Layering c. Root cutting d. Stem cutting

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Which chamber of the heart has the thickest muscular walls? a. Right atrium b. Left atrium c. Right ventricle d. Left ventricle Among the following fruits, which one is not a true fruit? a. Apple b. Date c. Coconut d. Tomato In human body, while one of the following glands is located in the neck? a. Adrenal b. Hypothalamus c. Pituitary d. Thyroid In human body, which one among the following secretes digestive enzyme? a. Large institute b. Liver c. Pancreas d. Spleen Which one among the following is a warm blooded animal? a. Anaconda b. Crocodile c. Shark d. Whale Which one among the following is an ape naturally found in India? a. Chimpanzee b. Hoolak Gibbon c. Gorilla d. Orangutan Which one among the following plants produces seeds without producing flower? a. Cashew nut b. Date Palm c. Pinus d. Toddy The stem of which one of the following plants is usually underground? a. Banana b. Sweet potato c. Topioca d. Water melon In the context of Wholesale Prize Index (WPI) in India, under the Primary Articles’ group, what is the approximate weight of ‘Food Article’ in WPI? a. 12 b. 15 c. 18 d. 21 Which one of the following is responsible for bringing out the report on National and Per Capita Income in India?

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a. Ministry of Planning b. Ministry of Human Resource Development c. Ministry of Home Affairs d. Ministry of Statistics and Programme Implementation In terms of both quantity and value, which one of the following countries is the largest cutting and polishing centre of diamonds in the world? a. Belgium b. France c. India d. South Africa Regarding the procurement of wheat for central pool, which one of the following States has the highest share of contribution? a. Haryana b. Madhya Pradesh c. Punjab d. Uttar Pradesh So far how many times has the countrywide “Economic Census” been done in India? a. Thrice b. Five times c. Seven times d. Nine times Which among the following was the capital of Shivaji? a. Singhagarh b. Raigarh c. Panhala d. Poona Who among the following arrived in the court of Jehangir as an official ambassador of King of England? a. William Hawkins b. Sir Thomas Roe c. Sir Edward Terry d. Bernier Which Mughal Emperor granted the Dewani of Bengal to the British East India Company in the year 1765? a. Jehangir b. Shahjahan c. Aurangzeb d. Shah Alam-II Who of the following was the representative of Indian National Congress in the Second Round Table Conference, held in London? a. Madan Mohan Malviya b. C. Rajagopalachari c. Mahatma Gandhi d. Vallabhbhai Patel Where did Lala Hardayal and Sohan Singh Bhakna form the Gadar Party in 1913? a. Paris b. San Francisco c. Tokyo d. London

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Prior to Independence, the elections to the Constituent Assembly were held under which one of the following? a. Mountbatten Plan b. Cabinet Mission c. Cripps Proposals d. Wavell Plan Who among the following introduced cashew nut, pineapple and tobacco into India? a. Dutch b. English c. French d. Portuguese When All India Trade Union Congress was founded in 1920, who of the following was elected its president? a. C.R. Das b. Lala Pajpat Rai c. N.M. Joshi d. V.V. Giri Which one of the following was the occasion on which Jawaharlal Nehru stepped forward, as an important national leader? a. Agitation against Rowlatt Act b. Launch of Non-Cooperation Movement c. Formation of Swaraj Party d. Agitation against the arrival of Simon Commission At the time of Tripuri Congress Session in 1939 in which Subhash Bose has defeated Sitaramayya, who among the following had withdrawn his candidature from Presidentship? a. Abdul Kalam Azad b. Jawaharlal Nehru c. Jayaprakash Narayan d. Vallabhbhai Patel Which one of the following was not a programme of the Non-Cooperation cell given in 1920? a. Boycott of titles b. Boycott of Civil Services c. Boycott of English education d. Boycott of police and army In which year was Mahatma Gandhi’s famous work Hind Swaraj written? a. 1907 b. 1909 c. 1914 d. 1934 Consider the following statements with reference to Union Government: 1. The tenure of Chairman/Members of Staff Selection Commission is for five years or still they attain the age of 62 years, whichever is earlier. 2. The tenure of Chairman/Member of Union Public Service Commission is for six years

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or till they attain the age of 65 years, whichever is earlier. Which of the statements given above is/are correct? a. 1 only b. 2 only c. Both 1 and 2 d. Neither 1 nor 2 According to the provisions of the Constitution of India, who inquires into all doubts and decides disputes arising out of or in connection with the election of Vice-President of India? a. The President of India b. The Supreme Court of India c. The Election Commission of India d. The Attorney General of India Who among the following tribes live in the Union Territory of Andaman and Nicobar Islands? a. Apatani b. Jarawa c. Munda d. Santhal Match List I with List II and select the correct answer using the code given below the lists: List I (Book) A. Crime and Punishment B. Farewell to Arms C. The Rights of Man D. Unto The Last List II (Author) 1. Ernest Hemingway 2. Feodor Dostoyevsky 3. John Ruskin 4. Thomas Paine Code: A B C D a. 2 3 4 1 b. 4 1 2 3 c. 4 3 2 1 d. 3 1 4 3 In India, when both, the offices of the President and the Vice-President happen to be vacant simultaneously, who will discharge the duties of the President? a. The Prime Minister b. The Union Home Minister c. The Speaker of Lok Sabha d. The Chief Justice of India For the review of which of the following was a Commission under the chairmanship of Justice M.N. Venkatachaliah constituted by Union Government? a. Industrial sickness b. River water disputes c. The Constitution of India

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d. Centre-State relations In which one of the following countries did the Industrial Revolution first take place? a. USA b. UK c. Germany d. France Who of the following is the author of the famous book ‘Das Kapital’? a. Adam Smith b. Karl Marx c. Rousseau d. Voltaire Which one of the following is the correct statement? In the Parliament of India, a money bill can be introduced only with the recommendation of a. the President of India b. the Prime Minister of India c. the Speaker of Lok Sabha d. the Union Finance Minister Which one of the following is a place of famous Hindu pilgrimage as well as a site of important hydroelectric power project? a. Devaprayag b. Guntur c. Nasik-Triambakeshwar d. Omkareshwar State which one of the following groups of oceanic water currents meet near ‘Newfoundland Island’ of Canada? a. Gulf Stream and Labrador b. Kuroshio and Kurile c. Agulhas and Mozambique d. Brazilian and Falkland How many Indian States border Myanmar? a. Three b. Four c. Five d. Six Match List I with List Ii and select the correct answer using the code given below the lists: List I (Name of the River) A. Godavari B. Krishna C. Tapti D. Cauvery List II (Tributary Joining) 1. Parna 2. Hemavati 3. Pranhita 4. Koyana Code: A B C D a. 1 4 3 2 b. 3 2 1 4 c. 1 2 3 4

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d. 3 4 1 2 Where is the Port of East London located? a. England b. Ireland c. East coast of USA d. South Africa Which one of the following pairs is not correctly matched? a. Northern Rhodesia : Namibia b. Gold Coast : Ghana c. Dutch Guyana : Suriname d. Dutch East Indies : Indonesia Khmer Rouge atrocities pertained to which one among the following? a. South Africa b. Iraq c. Libya d. Cambodia Recently, the President of India conferred the India Gandhi Prize for Peace, Disarmament and Development for 2006 on whom among the following? a. Kim Dae Jung b. Mohamed El Baradei c. Shirin Ebadi d. Wangari Muta Maathai In the year 2007, which one of the following pairs of countries launched spacecrafts to carry out research on the Moon? a. Australia and Canada b. China and Japan c. France and Germany d. Russia and South Korea In December, 2007, which one of the following countries launched in interceptor missile called AAD-02 to intercept a ballistic missile? a. Iran b. North Korea c. India d. Pakistan Recently, who of the following writers in English, has been awarded the Sahitya Akademi Fellowship? a. Amitav Ghosh b. Anita Desai c. Jhumpa Lahiri d. Shashi Tharoor In the context of Indian Defence, what is Admiral Gorshkov, frequently in the news? a. Stealth worship b. Nuclear powered submarine c. Aircraft carrier d. Marine oil drilling platform Hugo Chavez, who is frequently in the news, is a President of which one of the following countries? a. Argentina b. Brazil

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c. Cuba d. Venezuela What is the Defence outlay (approximate) in India for the year 2008-09? a. Rs. 65,000 crores b. Rs. 85,000 crores c. Rs. 95,000 crores d. Rs. 1,05,000 crores What is a major use of allethrin? a. In household insecticides b. In glass manufacture c. In steel manufacture d. In paints and varnishes Which one of the following is not correctly match (approximately)? a. 4 Imperial gallons = 18.18 litres b. 4 pounds = 1.81 kilograms c. 30 pounds per sq. in. = 2.07 kg per sq. cm. d. 5 hectares = 18.35 acres Big Mac Index is employed in the determination of which one of the following? a. Infrastructure development b. Purchasing power parity c. Defence budget per capita d. Crop yield What does the term ‘Pyrrhic Victory’ imply? a. A victory in a war wherein Air Force has played a major role b. A victory achieved at a great cost to the winner c. A victory of a political party wherein members of the opposition party have betrayed their own members d. A victory achieved in games as a result of match-fixing

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The well-known sportsman Liu Xiang has excelled in which event? a. Table Tennis b. Weightlifting c. Hurdles race d. Swimming Which one of the following subjects is mainly dealt with by Montreal Protocol? a. Undersea cable network b. International cooperation against terrorism c. Depletion of Ozone layer d. Exploration of outer space From which year does the 11th Five Year Plan start? a. 2005 b. 2006 c. 2007 d. 2008 In the context of India’s defence, what is C130 J Hercules? a. A supersonic fighter jet b. A troop transport aircraft c. An unmanned patrol aircraft d. A multi-purpose amphibious vehicle Who among the following is a blanker? a. Samir Jain b. Raghav Bahl c. K.V. Kamath d. G.M. Rao