objective physics

INAO (WORKSHOP) DAILY PRACTICE PROBLEMS SESSION-2009-10 Subject : Physics

01 DPP No. __

Topic : Light

1.

Two plane mirrors are at right angles to each other. A man stands between them and combs his hair with his right hand. In how many of the images will he be seen using his right hand : (A) Zero (B) 1 (C) 2 (D) 3

2.

The phenomenon utilised in an optical fibre is : (A) refraction (B) interference tion

3.

4.

(C) polarization

(D) total internal reflec-

Relation between critical angles of water and glass is : (A) Cw > Cg (B) Cw < Cg

(C) Cw = Cg

(D) Cw = Cg = 0

Mirage formation in deserts is due to : (A) Total internal reflection (C) Rayleigh scattering

(B) Bending of light by gravitational field of earth. (D) None of these

5.

The wavelength of light in two liquids ‘x’ and ‘y’ is 3500 Å and 7000 Å, then the critical angle of x relative to y will be : (A) 60° (B) 45° (C) 30° (D) 15°

6.

A ray of light propagates from glass (refractive index = 3/2) to water (refractive index = 4/3). The value of the critical angle is :

 8 1  (B) sin  (C) sin–1 (8 / 9) (D) sin–1 (5 / 7)  9    When light is incident on the interface of glass and air as shown in the figure. If green light is just totally internally reflected then the emerging ray in air contains : (A) sin–1(1/2)

7.

Air Glass

Green

White (A) Yellow, orange, red (C) All colours 8.

(B) Violet, indigo, blue (D) All colours except green

If the central portion of a convex lens is wrapped in black paper as shown in the figure:

(A) No image will be formed by the remaining portion of the lens. (B) The full image will be formed but it will be less bright. (C) The central portion of the image will be missing. (D)There will be two images each produced by one of the exposed portions of the lens.

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observer

9.

water

–– –––––––––––––––––––––– –––––––––– –––––––––– –––––––––––––––––––––– –– –––––––––––––––––––––– –––––––––– –––––––––– ––––––––––––––––––––– –– – –––––––––––––––––––––– –––––––––– –––––––––– –– –––––––––––––––––––––– –––––––––– –––––––––– –– –––––––––––– –––––––– –– –– –– –– –– –– –––––––––– –––––––––––––––––––––– ––––––––––––––––––––– –– – –––––––––––––––––––––– –––––––––– –––––––––– –– –––––––––––––––––––––– –––––––––– –––––––––– –– –––––––––––––––––––––– –––––––––– –––––––––– –––––––––––––––––––––– ––––––––––––––––––––– –– – –––––––––––––––––––––––––––––––– –– ––––––––

20cm

10cm air bulb

Apparent depth of the light bulb as seen by the observer (A) 80/3 cm (B) 100/3 cm 10.

(C) 200/3 cm

(D) 40 cm

Which of the following is a correct possibility:

o

30

µ2=1 (A)

(B)

o

60

µ2=1 (C)

(D) 60

11.

o

o 30 30

o

A ray of light is incident at the glass-water interface at an angle i, it emerges finally parallel to the surface of water, then the value of µg would be -

Air r water glass 4 (A)   sin i 3

12.

(B) 1sin i

r i (C) 4 3

(D) i

A point source of light is placed 4 m below the surface of liquid of refractive index 5/3. The minimum diameter ofa disc, which should be placed over the source, on the surface of water to cut off all light coming out of liquid is : (A)  (B) 6 m (C) 4 m (D) 3m

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13.

What should be the value of distance d so that final image is formed on the object itself. (focal lengths of the lenses are written on the lenses). 10 cm

–20 cm

O

10 cm d

(A) 10 cm

(B) 20 cm

(C) 5 cm

(D) none of these

14.

A square object of area 100 sq. cm is placed perpendicular to the principal axis of a concave mirror. If the lateral magnification of the mirror, for the above object position is 0.4, then the area of the image will be : (A) 16 sq. cm (B) 40 sq. cm (C) 100 sq. cm (D) 250 sq. cm

15.

When a graph is plotted taking angle of devation  along the y-axis and angle of incidence (i) along the x-axis, which of the following figures correctly represents this variation ?

(A)

16.

(B)

(C)

(D)

A ray falls on a prism ABC (AB = BC) and travels as shown in Fig. The minimum refractive index of the prism material should be : A 90º

90º C

B (A)

4 3

17.

(B)

(C) 1.5

2

f = 10 cm

(D)

3

f = 20 cm

L1

L2

S

10 cm

20 cm

At what distance from L1 will the final image of S is formed : (A) 10 cm (B) 20 cm (C) 30 cm

(D) 40 cm Page # 3

INAO (WORKSHOP) DAILY PRACTICE PROBLEMS SESSION-2009-10 Subject : Physics

1.

Topic : Magnetic Effect of Current

A moving charge will produce : (A) no field (B) an electric field

(C) a magnetic field

02 DPP No. __

(D) both (B) and (C)

2.

The magnetic field of induction at a point 4 cm from a long current wire is 10–3 T. The field of induction at a distance of 1.0 cm from the same current will be : (A) 2 × 10–4 T (B) 3 × 10–4 T (C) 4 × 10–3 T (D) 1.11 × 10–4 T

3.

Which of the following graph represents the variation of magnetic flux density B with distance r for a straight long wire carrying an electric current ?

B

B

(A)

(B)

r

r B

B

(C)

(D)

r

r

4.

Two parallel long straight conductors are placed at right angle to the meter scale at the 2 cm and 6 cm marks as shown in the figure. If they carry currents I and 3 I resp, in the same direction, then they will produce zero magnetic field at : I

0

(A) zero mark

1 2

3I

3 4 56

(B) 9 cm mark

7 8 9 10 11 12 13 14 15

(C) 3 cm mark

(D) 7 cm mark

5.

A current is passed through a straight wire. The magnetic field established around it has its lines of forces. (A) elliptical (B) circular (C) oval (D) parabolic

6.

A helium nucleus makes a full rotation in a circle of radius 0.8 meter in 2 sec. The value of the magnetic field induction B in tesla at the centre of circle will be : (A) 2 × 10–19 0 (B) 10–19 / 0 (C) 10–19 0 (D) 2 × 10–20 / 0.

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7.

A circular coil A of radius r carries current I. Another circular coil B of radius 2r carries current of I. The magnetic field at the centres of the circular coils are in the ratio of : (A) 3 : 1 (B) 4 : 1 (C) 1 : 1 (D) 2 : 1

8.

Two straight long wires are set parallel to each other with a distance of 2r between them. If each wire carries a current I in the same direction, the strength of magnetic field at a distance r between the two wires is : (A) zero (B) 4I/r (C) 2I/r (D) I/r

9.

If we double the radius of a current carrying coil keeping the current unchanged, the magnetic field at its centre will : (A) remain unchanged (B) become double (C) be halved (D) become four times

10.

A current carrying power line carries current from west to east. The direction of magnetic field 1m above the power line will be : (A) east to west (B) west to east (C) south to north (D) north to south

11.

I tesla is equal to : (A) NAm

(B) NA–1 m

(C) NAm–1

(D) NA–1 m–1

12.

A vertical straight conductor carries a current vertically upwards. A point P lies to the east of it at a small distance and another point Q lies to the west at the same distance. The magnetic field at P is : (A) greater than at Q (B) same as at Q (C) less than at Q (D) greater or less than at Q, depending upon the strenth of current

13.

In the figure.shown the magnetic field induction at the centre O of the arc due to current in portion CD will be :

I r I

I A (A) 0 I

B

(B) 0 I / 2r

O

C

D

(C) 0 I / 4r

(D) zero

14.

In the above question, the magnetic field induction at O due to whole length of the conductor is : (A) 0 i / r (B) 0 i / 2r (C) 0 i / 4r (D) zero

15.

In the figure.shown, there are two semi-circles of radii r1 and r2 in which a current I is flowing. The magnetic field induction at the centre O will be :

(A)

 0I r1  r2  4

(B)

 0I r1 – r2  4

 0I  r1  r2  (C) 4  r r   12 

 0I  r1 – r2  (D) 4  r r   1 2 

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INAO (WORKSHOP) DAILY PRACTICE PROBLEMS SESSION-2009-10 Subject : Physics

Topic : Thermometry and Expension

03 DPP No. __

Note : Question No. 1 to 5 have more than one answers are correct. 1.

To measure a temperature say around 400°C which of the following thermometres can be used most conveniently: (A) Gas thermometer (B) Mercury thermometer (C) Platinum thermometer (D) Thermocouple

2.

Which of the following statements are true? (A) Rubber contracts on heating (C) Water contracts on heating from 0 to 4°C

(B) Water expands on freezing (D) Water expands on heating from 4 to 40°C

3.

If ,  and  are coefficients of linear, superficial and volume expansion respectively then : (A) (/) = (1/2) (B) (/) = (2/3) (C) (/) = (3/1) (D) (/) = (/)

4.

Due to thermal expansion, with rise in temperature : (A) Metallic scale reading becomes lesser than true value (B) Pendulum clock becomes fast (C) A floating body sinks a little more (D) The weight of a body in a liquid increases

5.

Two identical beakers are filled with water to the same level at 4°C. If one say A is heated while the other B is cooled, then : (A) Water level in A will rise (B) Water level in B will rise (C) Water level in A will fall (D) Water level in B will fall

6.

Two rods of lengths L1 and L2 are made of materials whose coefficient of linear expansion are 1 and 2. If the difference between the two lengths is independent of temperature : (A) (L1/L2) = (1/2) (B) (L1/L2) = (2/1) (C) L211 = L222 (D) 21L1 = 22L2

7.

When a strip made of iron (1) and copper 2 (> 1) is heated : (A) Its length does not change (B) Its gets twisted (C) It bends with iron on concave side (D) It bends with iron on convex side

8.

An iron tyre is to be fitted onto a wooden wheel 1.0 m in diameter. The diameter of the tyre is 6 mm smaller than that of the wheel. The tyre should be heated so that its temperature increases by a minimum of (coefficient of volume expansion of iron is 3.6 × 10–5/C°) : (A) 167 C° (B) 334 C° (C) 500 C° (D) 100 C°

9.

If the length of a cylinder on heating increases by 2%, the area of its base will increases by : (A) 0.5% (B) 2% (C) 1% (D) 4%

10.

When a copper ball is heated, the largest percentage increase will occur in its : (A) Diameter (B) Area (C) Volume (D) Density

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11.

12.

A solid ball made of material having coefficient of volume expansion 8 × 10–6/°C is immersed in a liquid having coefficient of volume expansion 3 × 10–6/°C. The percentage change in upthrust when temperature is increased by 100°C is : (A) 0.05% (B) – 0.05% (C) 0.5% (D) 0.11% The water surface in a lake is just going to freeze. What is the temperature of water at the bottom : (A) 0°C (B) 4°C (C) Less than 0°C (D) More than 4°C

13.

During severe winter in the low temperature zones of the world, the superficial parts of the lakes are frozen leaving water below. What the freezing at the bottom is prevented because : (A) The conductivity of ice is low (B) The water has large latent heat of fusion (C) The water has large specific heat (D) The temperature of the earth at the bottom of lake is high

14.

When a block of iron floats in mercury at 0°C, a fraction k1 of its volume is submerged, while at the temperature 60°C, a fraction k2 is seen to be submerged. If the coefficient of volume expansion of iron is Fe and that of

k1 mercury is Hg, then the ratio k can be expressed as : 2

1  60 Fe (A) 1  60  Hg

1  60 Fe (B) 1  60  Hg

1  60 Fe (C) 1  60  Hg

(D)

1  60 Hg 1  60 Fe

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