Physics IJSO Stage-1

IJSO (STAGE-I) DAILY PRACTICE PROBLEMS SESSION-2012-13 Subject : Physics

Topic : Electricity

DPP No. 01

1.

A circuit has fuse of 5A. What is the maximum number of 100W (220 V) bulb that can be safely used in the circuit ? (A) 5 (B) 7 (C) 9 (D) 11

2.

For equal charges (each Q coulomb) are placed at the three corners of an equilateral triangle. What will be the nature and magnitude of charge q placed at the centre of the triangle so that the system will be in equilibrium : (A) –Q/ 3

3.

6.

(D) none of these

(B) 8

(C) 4/3

(D) 7/3

The equivalent resistance between the points A and B is :

(A) 5.

(C) – Q

The equivalent resistance between A and B will be (in )

(A) 2/7 4.

(B) –Q/4

36 7



(B) 10

(C)



85 7



(D) none of these

A uniform wire of resistance R is uniformly compressed along its length, until its radius becomes n times the original radius. Now, the resistance of the wire becomes : (A) R/n (B) n R (C) R/n2 (D) R/n4 Two charges +q and –q are placed at a distance b apart as shown in the figure below. B P

A

C b/2 +q

–q b

The electric field at a point P on the perpendicular bisector as shown as : (A) along vector  A

(B) along vector  B

(C) along vector  C

(D) Zero

7.

Two resistances 500 ohm and 1000 ohms are connected in series with a battery of 1.5 volt . The voltage across the 1000 ohms resistance is measured using a voltmeter having a resistance of 1000 ohm . The reading in the voltmeter would be :

(A) 1.5 volt 8.

(B) 1.0 volt

(C) 0.75 volt

(D) 0.50 volt

In the given network shown in the figure, the equivalent resistance is:

(A) R/3

(B) 2 R/3

(C) 5 R/3

(D) none

9.

An electrical bulb rated for 500 W at 100 V is used in a circuit having a 200V supply. Calculate the resistance that one must put in series with the bulb, so that the bulb delivers 500 W. (A) 30 (B)20 (C) 60 (D) None of these

10.

A current of 2A flow's in a system of conductors, the potential difference VA – VB (in volts) in figure? A

2A 1 4

(A) 12 V

(B) 14 V

2V 1V 2V 2V

B 1 4

(C) 8 V

(D) 10 V

WORKSHOP FOR IJSO (STAGE-I) DAILY PRACTICE PROBLEMS SESSION-2012-13 IIT-JEE | AIPMT | AIEEE | OLYMPIADS | KVPY | NTSE Subject : Physics 1.

Topic : Electricity

DPP No. 02

A wire is in the form of a tetrahedron. The resistance of each edge is r. The equivalent resistances between corners 1–2 and 1–3 are respectively

(A)

r r , 2 2

(B) r, r

(C)

r ,r 2

(D) r,

r 2

2.

A current of 2 A flows in system of conductors shown in figure. The potential difference VA – VB will be:

3.

(A) +1V (B) – 1V (C) +2V The slope of voltage (V) versus current (I) curve is called : (A) Resistance (B) Conductance (C) Resistivity

4.

(D) – 2V (D) Conductivity

Find equivalent resistance of the combination shown below : A

R

B R

(A) 2R 5.

R (B) 2

(C) Zero

(D) Intinite

Find the current flowing through the resistance R1 of the circuit shown in figure if the resistances are equal to R1 = 10 , R2 = 20 , and R3 = 30 , and the potentials of points 1, 2 and 3 are equal to 1 = 10 V, 2 = 6 V, and 3 = 5 V.

(A) 0.1 A

(B) 0.2 A

(C) 0.3 A

(D) 0.4 A

6.

You are given a wire 1 m long. In which one of the following cases, the energy drawn from the battery will be the largest ? Assume that the internal resistance of the battery is zero. (A) Full length of the wire connected across the battery (B) Half length of the wire connected across the battery (C) Wire cut into four equal parts and they are connected in parallel to each other across the battery (D) Wire is cut into two equal parts and they are connected in parallel to each other across the battery

7.

Two 1000 W heaters when connected in parallel across 220 V supply produced heat Qp in time t. If they are connected in series across the same power supply the heat produced in the same time is Qs. What is

Qp Qs

?

(A) 4 8.

(B) 2

(C) 0.5

(D) 0.25

If the reading of ammeter A1 in figure is 2.4 A. Neglecting the resistances of the ammeters, the reading of ammeter A2 will be :

(A) 1.6 A

(B) 1.2 A

(C) 1 A

(D) 2 A

9.

The resistance of the series combination of two resistances is S. When they are joined in parallel, the total resistance is P. If S = nP, then the minimum possible value of n is : (A) 4 (B) 3 (3) 2 (4) 1

10.

Two sources of equal emf are connected to an external resistance R. The internal resistances of the two sources are R1 and R2(R2 > R1). If the potential difference across the battery having internal resistance R2, is zero, then: (A) R =

R 2  (R1  R 2 ) (R 2  R1 )

(B) R = R2 – R1

R1R 2 (C) R = (R  R ) 2 1

R1R 2 (D) R = (R  R ) 2 1

IJSO (STAGE-I) DAILY PRACTICE PROBLEMS SESSION-2012-13 IIT-JEE | AIPMT | AIEEE | OLYMPIADS | KVPY | NTSE Subject : Physics 1.

Topic : Force & NLM

DPP No. 05

Five identical cubes each of mass m are on a straight line with two adjacent faces in contact on ahorizontal surface as shown in the fig. Suppose the surface is frictionless and a constant force P is applied from left to right to the end face of A; which of the following statements are correct ? P A B C D E (A) The acceleration of the system is

5P m

(B) The resultant force acting on each cube is (C) The force exerted on C by D is

P 5

P 5

(D) The acceleration of the cube D is

Pm 5

2.

A fully loaded elevator has a mass of 6000 kg. The tension in the cable as the elevator is accelerated downward with an acceleration of 2ms–2 is (Take g = I0 ms–2) (A) 7·2 × 104 N (B) 4.8 × 104 N (C) 6 × 104 N (D) 1.2 × 104 N

3.

A spring balance is attached to 2 kg trolley and is used to pull the trolly along a flat surface as shown in the fig. The reading on the spring balance remains at 10 kg during the motion. The acceleration of the trolly is (Use g= 9.8 m–2) :

(A) 4.9 ms–2

(B) 9.8 ms–2

(C) 49 ms–2

(D) 98 ms–2

4.

An object will continue accelerating until : (A) Resultant force on it begins to decreases (B) Its velocity changes direction (C) The resultant force on it is zero (D) The resultant force is at right angles to its direction of motion

5.

Block A is moving with a certain acceleration along a frictionless horizontal surface. When a second block B is placed on top of block A, the acceleration of the combined block drops to 1/5 the original value. What is the ratio of the mass of A to the mass of B : (A) 5 : 1 (B) 4 : 1 (C) 3 : 1 (D) 2 : 1

6.

Five identical cubes each of mass m are on a straight line with two adjacent faces in contact on ahorizontal surface as shown in the fig. Suppose the surface is frictionless and a constant force P is applied from left to right to the end face of A; which of the following statements are correct ? P A B C D E

5P m 2P (C) The force exerted on C by D is 5 (A) The acceleration of the system is

(B) The resultant force acting on each cube is (D) The acceleration of the cube D is

Pm 5

P 5

7.

Two forces of 6N and 3N are acting on the two blocks of 2kg and 1kg kept on frictionless floor. What is the force exerted on 2kg block by 1kg block ?:

6N 2kg 1kg (A)1N

8.

(B) 2N

3N

(C) 4N

(D) 5N

Figure shows four blocks that are being pulled along a smooth horizontal surface. The mssses of the blocks and tension in one cord are given. The pulling force F is : F 30N 4kg

60º

(A) 50 N

3kg

(B) 100 N

2kg

(C) 125 N

1kg

(D) 200 N

9.

A small block of mass 1kg is kept on a rough inclined wedge of inclination 45° fixed in an elevator. The elevator goes up with a uniform velocity v = 2m/s and the block does not slide on the wedge. Then the work done by force of friction on block in 1 sec is : [g = 10 m/s2] (A) 5 J (B) 10 J (C) 15 J (D) 20 J

10.

The velocity of end ‘A’ of rigid rod placed between two smooth verticle walls moves with velocity ‘u’ alons verticle directions, Find out the velocity of end B of that rod, rod always remains in centact with verticle wall.

A u

B (A) usin

(B) utan

(C) ucos

(D) ucot

WORKSHOP FOR IJSO (STAGE-I) DAILY PRACTICE PROBLEMS SESSION-2012-13 IIT-JEE | AIPMT | AIEEE | OLYMPIADS | KVPY | NTSE Subject : Physics

1.

Topic : Force & NLM

DPP No. 06

Three equal weights of mass m each are hanging on a string passing over a fixed pulley as shown in figure. What are the tensions in the string connecting weights A to B and B to C ?

a

T1 T1 m A

B m T2

a

C m

(A) 2.

2 mg 3

3 mg 2

(C)

1 mg 2

(D) none of these

Same spring is attached with 2 kg, 3 kg and 1 kg blocks in three different cases as shown in figure. If x1, x2 and x3 be the extensions in the spring in these cases then (Assume all the blocks to move with uniform acceleration)

(A) x1 = 0, x3 > x2 3.

(B)

(B) x2 > x1 > x3

(C) x3 > x1 > x2

(D) x1 > x2 > x3

A large cubical shaped block of mass M rests on a fixed horizontal surface. Two blocks of mass m 1 and m 2 are connected by a light inextensible string passing over a light pulley as shown. Neglect friction everywhere. Then the constant horizontal force of magnitude F that should be applied to M so that m 1 and m 2 do not move relative to M is :

m2 (A) F = m (m 1 + m 2 + M)g 1

m1 (B) F = m (m 1 + m 2 + M)g 2

m1 (C) F = m (m 1 + M)g 2

m2 (D) F = m (m 1 + M)g 1

4.

The pulley arrangements shown in figure are identical the mass of the rope being negligible. In case I, the mass m is lifted by attaching a mass 2m to the other end of the rope. In case II, the mass m is lifted by pulling the other end of the rope with a constant downward force F= 2 mg, where g is acceleration due to gravity. The acceleration of mass in case I is :

5.

(A) Zero

(B) More than that in case II

(C) Less than that in case II

(D) Equal to that in case II

A string is wrapped round a log of wood and it is pulled with force F as shown in figure :

(A) If increase  then tension T increase (B) if  inereace then tension T decrease (C) T > F if  > /3 (D) T > F if  > /4 6.

7.

A string of negligeble mass going over a clamped pully of mass m supports a block of mass M as shown in figure the force on the pully by the clamp is given by :

(A)

2 mg

(B)

2 Mg

(C)

(M  m)2  m2 g

(D)

(M  m)2  m2 g

The mass of block ‘ A ‘ for the system to be in equilibrium is : { Neglect friction}

A

g 2k

30°

2kg

(A) 1kg

(B) 3kg

(C) 5kg

(D) 7kg

8.

In the system shown in the figure, the acceleration of the 1kg mass and the tension in the string connecting between A and B is :

g 8g downward, 4 7 g 6 (C) downward, g 7 7

g g upward, 4 7 g (D) upward, g 2

(A)

9.

(B)

Two persons are holding a rope of negligible weight tightly at its ends so that it is horizontal. A 15 kg weight is attached to the rope at the mid point which now no longer remains horizontal. The minimum tension required to completely straighten the rope is : (A) 15 kg

15 kg 2 (C) 5 kg (B)

(D) Infinitely large (or not possible) 10.

Four equal and parallel forces are acting on a rod (as shown in figure) at distances of 20 cm, 40 cm, 60 cm and 80 cm respectively from one end of the rod. Under the influence of these forces the rod :

F 0

20 F

40

F 60 F

(A) Is at rest (B) Experiences a torque (C) Experiences a linear motion (D) Experiences a torque and also a linear motion

80

IJSO(STAGE-I) DAILY PRACTICE PROBLEMS SESSION-2012-13 IIT-JEE | AIPMT | AIEEE | OLYMPIADS | KVPY | NTSE Subject : Physics

Topic : Light

DPP No. 03

1.

What should be the minimum height of plane mirror required to view complete image of a wall of height H behind you : (A) H/2 (B) H/3 (C) H/4 (D) H

2.

A plane mirror is rotated by an angle  in the plane perpendicular to the plane of incidence. The reflected ray will turn by an angle : (A) 

(B) 2

(C)

 2

(D) Does not turn

3.

A plane mirror is rotated by an angle  about the plane perpendicular to the plane of incidence. The reflected ray will turn by an angle : (A)  (B) 2 (C) 3 (D) None of these

4.

Two parallel plane mirrors A and B are placed at a separation 10 cm as shown in figure. A ray incident on the corner of mirror B at an angle of incidence 45º. Find the number of times this rays is reflected from mirror A:

(A) 4

5.

(B) 5

(C) 6

(D) 7

Find the angle at which reflected ray will strike the upper mirror.

(A) 10º

(B) 0º

(C) 5 º

(D) 20º

6.

As per New Cartesian Sign Convention : (A) Focal length of concave mirror is positive and that of convex mirror is negative (B) Focal length of both, convex and concave mirror is positive (C) Focal length of both, convex and concave mirror is negative (D) Focal length of concave mirror is negative and that of convex mirror is positive

7.

How far a concave mirror of focal length 20 cm should be kept from over face if we want to see exact inverted image of our face ? (A) 30 cm (B) 40 cm (C) 50 cm (D) 60 cm

8.

Focal length of a convex mirror is 10 cm. An object is placed at 10 cm from the mirror. Find the position of the image. (A) 5 cm (B) 15 cm (C) 18 cm (D) 20 cm

9.

Which of the following correctly depicts the graphical variation in case of a spherical mirror ?

(A)

10.

(B)

(C)

(D)

In normal incidence from plane mirror what will be angle of deviation : (A) 0º (B) 90º (C) 180º

(D) 360º

IJSO (STAGE-I) DAILY PRACTICE PROBLEMS SESSION-2012-13 IIT-JEE | AIPMT | AIEEE | OLYMPIADS | KVPY | NTSE Subject : Physics

Topic : Light

DPP No. 04

7 . Find the minimum possible value of angle of incidence, so that the light 3 ray cannot pass the second surface. (A) 60º (B) 30º (C) 45º (D) 90º

1.

For a prism, A = 60º , n =

2.

A concave mirror of radias R is kept on horizontal table. Water (repractive index ) is poured into it upto height h. Where should an object should placed (its distance from water surface) so that its final image is formed on itself. (A)

3.

R 

(B)

h 

(C)

R–h 

(D)

Rh 

A rectangular glass wedge is covered into water ( = 4/3) . The refractive index of glass is g = 1.5 . At what angle  will be the beam of light normally incident on AB reaches AC entirely.

A

B

C

4.

8 8 8 8 (A)  < sin–1   (B)  > sin–1   (C)  < cos–1   (D)  > cos–1   9 9 9       9 A beam of diameter d is incident on glass hemisphere as shown. If the radias of curvature of the hemisphere is very large in comparision to d, then the diameter of beam at the base of hemisphere will be d

=1

5.

= 3 2 3 d (A) d (B) d (C) 4 3 Find the focal length of the lens shown in figure when ns = 2.5

(D)

2 d 3

n=2

ns R.O.C.= 60cm (A) 360 cm 6.

(B) 

ns R.O.C.= 40cm (C) –600cm

(D) 100 cm

In a tank, a 4 cm thick layer of water (= 4/3) floats on a 6 cm thick layer of an organic liquid ( = 1.48) viewing at normal incidence, how far below the water surface does the bottom of water tank appear to be: (A) 8 cm (B) 7.05 cm (C) 10 cm (D) 6 cm

7.

If a convex mirror of focal length ‘f’ produces an image n times the size of the object, then the magnitude of u is : (A) u 

(n  1)f n

(B) u =

(1n)f n

 n  (C) u   f  n  1

 n  (D) u =  1n  f

8.

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

9.

A mirage occurs because : (A) the refractive index of atmosphere increases with height. (B) the refractive index of atmosphere decreases with height. (C) refractive index remains constant with height. (D) the hot ground acts like a mirror

10.

The power of plane mirror is equal to : (A) 0 (B) 

(C) 1

(D) –1

PHYSICS _IJSO STAGE-I_DPP-1

Que s. Ans.

1 A

2 A

3 A

4 C

5 D

6 A

7 C

8 A

9 A

10 A

PHYSICS _IJSO STAGE-I_DPP-2 Ques. Ans.

1 D

2 D

3 C

4 A

5 B

6 C

7 C

8 B

9 A

10 B

PHYSICS _IJSO STAGE-I_DPP-3

Ques.

1

2

3

4

5

6

7

8

9

10

Ans.

B

D

B

B

B

D

B

A

C

C

8 B

9 A

10 A

8 D

9 B

10 B

PHYSICS _IJSO STAGE-I_DPP-4

Ques. Ans.

1 B

2 C

3 B

4 D

5 C

6 B

7 B

PHYSICS _IJSO STAGE-I_DPP-5

Ques. Ans.

1 B

2 B

3 C

4 C

5 B

6 B,C

7 C

PHYSICS _IJSO STAGE-I_DPP-6

Ques. Ans.

1 A

2 B

3 B

4 C

5 A

6 D

7 B

8 C

9 D

10 B

PHYSICS _IJSO STAGE-I_DPP-7 Ques. Ans.

1 D

2 C

3 D

4 A

5 B

6 B

7 C

8 C

9 C

10 C