Physics

WORKSHOP FOR IJSO (STAGE-I) DAILY PRACTICE PROBLEMS SESSION-2011-12 IIT-JEE | AIPMT | AIEEE | OLYMPIADS | KVPY | NTSE 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 (B) –Q/4 (C) – Q (D) none of these

3.

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

(A) 2/7

4.

6.

(C) 4/3

(D) 7/3

The equivalent resistance between the points A and B is :

(A) 5.

(B) 8

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-2011-12 IIT-JEE | AIPMT | AIEEE | OLYMPIADS | KVPY | NTSE Subject : Physics

Topic : Force & NLM

DPP No. 02

1.

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

2.

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

(A) The acceleration of the system is

B

D E

5P m

(B) The resultant force acting on each cube is

(C) The force exerted on C by D is

C

P 5

2P 5

(D) The acceleration of the cube D is

Pm 5

3.

A weight is supported by two strings 1.3 and 2.0 m long fastened to two points on a horizontal beam 2.0 m apart. Thedepth of this weight below the beam is : (A) 1.0 m (B) 1.23 m (C) 0.77 m (D) 0.89 m

4.

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

5.

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 mg 3

(B)

3 mg 2

(C)

1 mg 2

(D) none of these

6.

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 7.

8.

(B*) x2 > x1 > x3

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

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 :

(B) More than that in case II (D) Equal to that in case II

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 10.

(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 :

(A) Zero (C) Less than that in case II 9.

(C) x3 > x1 > x2

(B) 9.8 ms–2

(C) 49 ms–2

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

(D) 98 ms–2

WORKSHOP FOR IJSO (STAGE-I) DAILY PRACTICE PROBLEMS SESSION-2011-12 IIT-JEE | AIPMT | AIEEE | OLYMPIADS | KVPY | NTSE Subject : Physics 1.

Topic : Magnetic Effect of Current

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

(C) a magnetic field

DPP No. 03

(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.

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

5.

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.

6.

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

7.

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

8.

Deflection in the galvanometer :

+

G

– motion

S

(A) towards right

(B) left

(C) no defection

(D) none of these

9.

A long copper wire is wound in the form of a coil of radius r. A current of 2 A is passed through this coil and the magnetic induction at the centre of this coil is noted. The same wire is now folded end to end and coil of the same radius r is prepared and the same current is passed through it. The magnetic induction at the centre: (A) will be doubled (B) will be halved (C) will remain same. (D) will drop to zero

10.

In a transformer, the number of turns of primary coil and secondary coil are 5 and 4 respectively. If 220 V is applied on the primary coil, then the ratio of primary current to the secondary current is : (A) 4 : 5 (B) 5 : 4 (C) 5 : 9 (D) 9 : 5

WORKSHOP FOR IJSO (STAGE-I) DAILY PRACTICE PROBLEMS SESSION-2011-12 IIT-JEE | AIPMT | AIEEE | OLYMPIADS | KVPY | NTSE Subject : Physics

Topic : Light

DPP No. 04

1.

A concave mirror and a convex lens are held separately in water. Then the focal length of (A) convex lens increases whereas that of concave mirror remains unchanged. (B) concave mirror changes whereas that of convex lens remains unchanged. (C) convex lens decreases whereas that of concave mirror remains unchanged. (D) both changes.

2.

The difference between blue and red light is that (A) blue light has lower energy than red light (B) blue light has a higher frequency than red light (C) blue light has a longer wavelength than red light (D) blue light has a faster speed in a vacuum than red light

3.

The lateral displacement of an incident ray passing out of a rectangular glass slab is : (A) directly proportional to the angle of incidence. (B) independent of the thickness of the glass slab. (C) inversely proportional to the thickness of the glass slab. (D) directly proportional to the square thickness of the glass slab.

4.

In the absence of atmosphere, the length of the day on earth will (A) decrease (B) increase (C) remain the same (D) depend upon the weather

5.

Raju finds that he can see tiny particles when a beam of sunlight enters a smoke-filled room through a small hole. The phenomenon, which accounts for it is (A) reflection (B) refraction (C) Tyndall effect (D) dispersion

6.

When a monochromatic light is incident on a prism, (A) dispersion will take place (B) lateral displacement will take place (C) emergent ray will be parallel to incident ray (D) bending of light ray will take place

7.

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

8.

The focal length of a concave mirror is f and the distance from the object to the principal focus is a. The magnitude of magnification obtained will be : (A) (f + a)/f

(B) f /a

(C)

f/ a

(D) f2/a2

9.

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

(n  1)f n

(B) u =

(1n)f n

 n  (C) u   f  n  1

 n  (D) u =  1n  f

10.

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

11.

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

(C) polarization

(D) total internal reflection

12.

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

13.

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°

14.

To get three images of a single object, one should have two plane mirrors at an angle of : (A) 60º (B) 90º (C) 120º (D) 30º

15.

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

(C) 1

(D) –1

WORKSHOP FOR IJSO (STAGE-I) DAILY PRACTICE PROBLEMS SESSION-2011-12 IIT-JEE | AIPMT | AIEEE | OLYMPIADS | KVPY | NTSE Subject : Physics

1.

Topic : Graviation&Fluid, WEP

(A) t1 > t2 (B) t1 < t2 (C) t1 = t2 (D) information incomplete

a

d

A particle of mass m describe a circle of radius r the centripetal acceleration on the particle is 4/r2. What will be the momentum of the particle: (A) 4 m/r

3.

05

The motion of a planet around sun in an elliptical orbit ( sun is situated on one focus) is shown in figure. The shaded areas are equal if the planet takes time t1 and t2 in moving from a to b and c to d respectively then : b c

sun

2.

DPP No.

(C) 4m r

(B) 2m/r

(D) 2m/ r

By what percentage should we increase the speed of satellite, which is revolving round the earth very close to its surface, so that if may go out of the influence of earth’s attraction ? (A) 5% (B) 20.7% (C) 41.4% (D) 50% th

4.

p If body floats with   of its volume above the surface of water then the relative density of the body is: q (A)

qp q

(B)

qp q

(C)

qp p

(D)

p q

5.

With what initial velocity should a body be projected vertically up from earth’s surface so that it may reach a height ten times the radius of the earth ? (A) 1.1 × 104 m/s (B) 2.2 × 104 m/s (C) 5.5 × 103 m/s (D) 4.4 × 103 m/s

6.

A rubber balloon of negligible mass is filled with 500 g of water. Its weight in water will be (A) 250 g (B) 500 g (C) zero (D) 100 g

7.

A vessel contains some water. It is moving towords right on a horizontal plane with a constant acceleration a . Which of the following figure represents correct water surface ?

(A)

a

(B)

a

(C)

a

a (D)

8.

A bullet of mass m is fired in the horizontal direction with a velocity u This bullet gets embeded in a bag of sand lying in a truck. If the mass of truck with bag is M then the velocity of truck after the collision will be :

u m

v M

Before Collision (A) 9.

(B)

m (M  m) u

(C)

mM (M  m) u

(D) zero

A bullet of mass ‘a’ and velocity ‘b’ is fired into a large block of wood of mass ‘c’. The bullet gets embedded into the block of wood. The final velocity of the system is : (A)

10.

mu (M  m)

(m+M) After Collision

b c ab

(B)

ab a c

(C)

a b ac

(D)

ac b a

A particle of mass m moving eastward with a speed v collides with another particle of the same mass moving northwards with the same speed. If two particles coalesce on collision, the new particle of mass 2 m will move in the north-east direction with a velocity : (A) v / 2

(B) v 2

(C) v / 2

(D) None of these

11.

A spring of force constant 800 N/m has an extension of 5 cm. The work done is extending it from 5 cm to 15 cm is : (A) 16 J (B) 8 J (C) 32 J (D) 24 J

12.

A body accelerates uninformly from rest to a velocity of 1 ms–1 in 15 seconds. The kinetic energy of the body will be (A) 4s

2 J when ‘t’ is equal to [Take mass of body as 1 kg] : 9 (B) 8s (C) 10s

(D) 12s

13.

A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle, the motion of the particles takes place in a plane. It follows that : (A) Its kinetic energy is constant (B) Its acceleration is constant (C) Its velocity is constant (D) It moves in a straight line

14.

In figure, a carriage P is pulled up from A to B. The relevant coefficient of friction is 0.40. The work done will be :

(A) 10 kJ 15.

(B) 23 kJ

(C) 25 kJ

(D) 28 kJ

A force F acting on an object varies with distance x as shown here. The force is in N and x in m. The work done by the force in moving the object from x = 0 to x = 6 m is :

(A) 18.0 J

(B) 13.5 J

(C) 9.0 J

(D) 4.5 J