entrance_questions.pdf

7/27/2019 entrance_questions.pdf

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MOST IMPORTANT OBJECTIVE TYPE QUESTIONS OF PHYSICS by

JATIN KHERA M.TECH I.I.T

PHYSICS SIMPLIFIED by JATIN KHERAM.Sc (PHYSICS) D.U, B.Ed M.Tech I.I.T

CONTACT: 9818508842, 9250758877

1. A driver applies the brakes on seeing traffic signal 400 m ahead. At the time of applying the brakes, vehiclewas moving with 15 m/s and afterwards it starts retarding with 0.3 m/s. The distance of vehicle after 1 min,

from the traffic light is

A.25 m B. 375 mC. 360 m D. 40 m

2. A particle is moving along the path given by y = C/6 t (where C is a positive constant). The relation betweenthe acceleration (a) and the velocity(v) of the particle at t = 5 sec is

A. 5a = v B. a = 5vC. a = v D. a = v

3. Which of the following statement can be possible cases in one/two-dimensional motion?A. A body has zero velocity and is still accelerating.B. The velocity of an object reverses direction when acceleration is constant.C. An objects speed goes on increasing even magnitudes of its acceleration decreases.D.None of the above.

4. A motor boat is to reach at a point 30 upstream on other side of river flowing with velocity 5 m/s.Velocity of motor boat with respect to water is 5 3 m/s. The driver should steer the boat at an angle of

A. 30 up w.r.t. the line of destination from the starting point.B. 60 up w.r.t normal to blank.C. 120 w.r.t. stream direction.D.None of the above.

5. Choose the wrong statement from the following.A. Zero velocity of a particle does not necessarily mean that its acceleration is zero.B. Zero acceleration of a particle does not mean that its velocity is zero.C. If speed of a particle is constant, its acceleration must be zero.D.None of the above.

6. The raindrops are hitting the back of a man walking at speed of 5 Km/hr. If he now starts running in the samdirection with a constant acceleration, the magnitude of the velocity of the rain with respect to him willA. Gradually increases. B. gradually decreasesC. first decreases then increases D. first increases then decreases.


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7. A particle is thrown at time t = 0 with a velocity of 10 m/s at an angle of 60 with the horizontal from a poinon an incline plane, making an angle of 30 with the horizontal. The time when the velocity of the projectilebecomes parallel to the incline is

A. 2/3 sec B. 1/3 secC. 3 sec D. 1/23 sec

8. When a body is thrown up in a lift with a velocity u relative to the lift, the time of flight is found to be t. Theacceleration with which the lift is moving up is

A. (u gt)/t B. (u + gt)/tC. (2u - gt)/t D. u/t 2g

9. A particle of mass 3m is dropped from certain height at t = 0 at time t = t1. The particle explodes and breaksinto two parts m and 2m. At time t = 3t1 velocity of lighter mass is V = V1 + V2 . The velocity of heaviermass at t = t1 (just after explosion) is ( if y represents vertical and x represents horizontal)

A. V1 V2 B. V1/2 + (- V2 + 5gt1)/2 C. V1/2 + (- V2 + 5gt1) /2 C. None of these.

10.A box is falling freely. Inside the box, a particle is projected with some velocity v with respect to the box at aangle as shown in the figure.Assertion (A): The path of the particle with respect to an observer sitting in the boxWill be straight line.Reasoning (R) : The acceleration of particle with respect to box is zero. Then,

A. Both A and R are correct and R is correct explanation of A.B. Both A and R are correct but R is not correct explanation of A.C. Both A and R is correct.D. Both A and R are wrong.

11.Two small rings O and O are put on two vertical stationary rods AB andAB, respectively. One end of an inextensible thread is tied at point A. Thethread passes through ring O ant its other end is to ring O.Assuming that ring O moves downwards at a constant velocity v1,Determine the velocity v2 of the ring O, angle AOO =

A. v1[(2sin/2)/cos ] B. v1[(2cos/2)/sin ]C. v1[(3cos/2)/sin ] D. None of these.


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12.A fixed U-shaped smooth wire has a semi-circular bending between Aand B as shown in figure. A bead of mass m moving with uniformspeed v through the wire enters the semicircular bend at A and leaves at

B.The Magnitude of average force exerted by the bead on the part AB of the wire isA. 0 B. 4mv/ dC. 2mv/ d D. none of these.

13.Two blocks of mass 10 Kg and 30 Kg are kept as shown in the figure. The surface between the blockis frictional while the ground is smooth. A horizontal forceOf magnitude 60N is applied horizontally on the upper block,Find the frictional force on the block of mass 30 Kg?

A. 20 N B. 30 NC. 40 N D. 50 N

14.Two identical particles A and B, each of mass m, are interconnected by a spring of stiffness k. If theparticle B experiences an external force F along the line of spring and outward (as shown) and theelongation of the spring at this instant is x, the acceleration of particle B relative to particle A is equalto

A. F/2m B. (F kx)/mC. (F -2kx)/m C. kx/m

15.The system shown in the figure is in equilibrium. Masses m1 & m2 are 2 Kg& 8 Kg respectively. Spring constant k1 & k2 are 50 N/m and 70 N/m respectively.If the comparison in first spring? (Both springs have same natural length)

A. 1.3 m B. -0.5 mC. 0.5 m D. 0.9 m

16.In figure the block of mass M is at rest on the floor. The accelerationwith which a boy of mass m should climb along the rope of negligiblemass so as to lift the block from is,

A. [M/m 1]g B. >[M/m 1]gC. (M/m)g D. >(M/m)g

17.Three blocks A, B and C of equal mass m are placed one over other on africtionless surface (table) as shown in figure. Coefficient of friction betweenany block A, B and C is . Maximum value of mass of block Md so that the


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block A,B and C move without slipping over each other is

A. (3m)/ +1 B 3m(1 )/

C. [3m(1 + )]/ D. 3m/(1 - )

18.Two blocks of masses 0.2 Kg and 0.5 Kg, which are placed 22 mapart on a rough horizontal surface ( = 0.5), are acted upon bytwo forces of magnitude 3 N each as shown in figure at time t = 0.Then, the time t at which they collide each other is

A. 1 sec B. 2 secC. 2 sec D. None of these.

19.A force given by the relation F = 8t, acts on body of mass 2 Kg, initially at rest. Find the work done bythis force on the body during first 2 seconds of its motion.

A. 64 J B. 0C. -64 J D. None of these

20.A particle of mass m is moving horizontally with a constant velocity v towards a rigid wall that ismoving in opposite direction with a constant speed u. Assuming elastic impact between the particleand wall, the work done by the wall in reflecting the particle is equal to

A. (1/2)m(u + v) B. (1/2)m(u + v)C. (1/2)muv D. 2mu (u + v).

21.A block of mass m is moving with constant acceleration a on a rough horizontal plane. If thecoefficient of friction between the block and ground is the power delivered by the external agentafter a time t from the beginning is equal to

A. mat B. mgatC. m(a + g)gt D. m(a + g)at

22.An electric motor creates a tension of 4500 N in hoisting a cable and reels it at the rate of 2 m/s. Whatis the power of the electric motor?

A. 15 kW B. 9 kWC. 225 kW D. 9000 H.P.


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23.A body is acted upon by a force which inversely proportional to the distance covered. The work donewill be proportional to

A. s B. sB. s D. kln(s/s1)

24.A machine delivers power to a body which is proportional to velocity v of the body. If the bodystarts with a velocity which is almost negligible, then distance covered by the body is proportional to

A. v B. (v/2) C. v D. v

25.The kinetic energy acquired by a mass m in traveling a certain distance d, starting from rest, under theaction of a force F such that the force F isA. directly proportional to t B. independent of tC. directly proportional to (t) D. directly proportional to t

26.A particle of mass m slides on a frictionless surface ABCD, startingfrom rest as shown in figure. The part BCD is circular arc. If itlooses contact at point P, find the maximum height attained by the particle from point C.

A. R [ 2 + 1/22] B. R [ 2 - 1/22]C. 3R D. none of these.

27.A projectile is fired with some velocity making certain angle with horizontal. Which of the followinggraphs is the best representation for the kinetic energy of a projectile (K.E.) versus its horizontaldisplacement(x)?

A. B.

C. D.

28.A force shown in the F-x graph is applied to a 2 kg block horizontalAs shown in the figure. The change in the kinetic energy is


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A. 15 J B. 20 JC. 25 J D. 30 J

29.A particle of mass m is released from height h on the smooth quartercircular fixed wedge. The horizontal surface AB following the circularpath at bottom of wedge is rough with coefficient of friction betweensurface and m. Find the distance from bottom of wedge where the mass willstop.

A. 2H/ B. h/ C. h/ g D. none of these.

30.A particle of mass 5m which is at rest explodes into 3 fragments. Two equal fragments each of mass 2m are found to move with a speed v each in opposite directions. The energy released in the process of

explosion isA. 2mv B. 5/2mvC. 5mv D. 3mv

31.A particle of mass m collides with another stationary particle of mass M. If the particle m stops justafter the collision, the coefficient of restitution of collision is equal to

A. 1 B. m/MC. (M m)/ (M + m) D. m/(M + m)

32.A pingpong ball of mass m is floating in air by a jet of water emerging out of nozzle. If the waterstrikes the ping pong ball with a speed v and just after collision water falls dead, the mass flow rate ofwater in the nozzle is equal to:

A. 2mg/v B. mv/gC. mg/v D. None of these.

33.A block of mass m is pushed towards a movable wedge of mass nm and heighth, with a velocity u. All surfaces are smooth. The minimum value of u for whichthe block will reach the top of the wedge is

A. (2gh) B. n2ghC. [2gh(1 + 1/n)] D. [2gh(1 - 1/n)]


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34.A circular arc (AB) of thin wire frame of radius R and mass M makes an angleof 90 at the origin. The centre of mass of the arc lies at

A. [0, (2/)R ] B. [0, (2/)R ]C. [0, (22/)R ] D. [0, (4/)R ]

35.From a 16 cm X 8 cm rectangular uniforms plane sheet, exactly onequarter of the sheet is removed as shown in the figure. If the originbe taken at the centre of the sheet considered as shown in the figurethe coordinate of the centre of mass of the remaining sheet is

A. (4/3, 2/3) B. (0, 2/3)C. (4/3, 0) D. (-4/3, -2/3)

36.A block B is at rest on the rough horizontal surface as shown. Anotherblock A collides with B. Then, which of the following statement is correct?(i) Impulsive friction acts on block B.(ii) Conservation of momentum can not be applied on a system (A + B) along x-axis for the situationjust before and just after the collision.(iii) Conservation of momentum can be applied on a system (A + B) along x-axis for the situation justbefore and just after the collision.(iv) Block A always moves along positive x-axis after collision.

A. i and ii B. i, ii and ivC. i and iv D. iii

37.Infinite number of bricks are placed one over the other asshown in the figure. Each succeeding brick having half the lengthand breadth of its preceding brick and the mass of each succeedingbrick being (1/4)th of the preceding one. Taking O as the origin, the xcoordinate of centre of mass of the system of bricks is at

A. a/7 B. 3a/7C. -3a/7 D. -2a/7

38. A particle strikes a smooth horizontal surface at an angle of 45 with a velocity of 100m/s andrebounds. If the coefficient of restitution between the floor and the particle is 0.57 then the anglewhich the velocity of the particle after it rebounds will make with the floor is

A. 30 B. 45C. 60 D. 90


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39. When a body rolls without sliding up an inclined plane, the frictional force is

A. directed up the plane B. directed down the plane

C. Zero D. dependent on its velocity

40. A particle m starts with zero velocity along a line y = 4d. The position of particle m varies asx = A sin . At t = /2, its angular momentum with respect to origin

A. mAd B. md/AC. mAd/ D. 0

41. As shown in the diagram a frame which is initially in the horizontal planeis rotated about AB. Find the angular velocity of the system at the momentit comes in vertical plane from the initial position.( Assume it being made up

of uniform rod of length l & l/2 (mass of length l = m)A. = (3g)/(33l) B. = (86g)/(33l)C. = (48g)/(17l) D. = (8g)/(7l)

42. A sphere of radius R and mass M collides elastically with a cubical blockof mass M and side 2R. The entire system is on a smooth horizontal groundGiven that the sphere was rolling without slipping with an angular velocity at the time of collision. The velocities of the sphere and the block after thecollision are

A. (sphere) = 0, v(sphere) = 0, v(block) = v.

B. (sphere) = , v(sphere) = 0, v(block) = v. C. (sphere) = 0, v(sphere) = 0, v(block) = 0.D. (sphere) = /2, v(sphere) = v/2, v(block) = v/2.

43. A body of mass m and radius r is released from rest along a smooth inclined plane of angle ofinclination . The angular momentum of the body about the instantaneous point of contact after a timet from the instant of release is equal to

A. mgrt cos B. mgrt sinC. (3/2)mgrt sin D. None of these.

44. Let I be the moment of inertia of a uniform square plate about an axis AB that passes though its centreand is parallel to two of its slides. CD is a line in the plane of the plate that passes through the centreof the plate and makes an angle with AB. The moment of inertia of the plate about the axis CD isthen equal to

A. I B. IcosC. Isin D. Icos/2


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45. When a car negotiates a curve, the normal force exerted on the inner and outer wheels are N1 and N2,Respectively. Then N1/N2 is

A. =1 B. 1 D. 0

46. A mass less string is wrapped around a hollow cylinder having mass m and radius r.the cylinder is kept on a rough horizontal surface (coefficient of friction is ). A constantForce F is applied as shown in the figure. In case of pure rolling, the friction force actingon the bottom most point of the cylinder is

A. 0 B. mgC. mg/2 D. 3 mg/2

47. A cubical box of side length L rests on a rough horizontal surface havingCoefficient of friction . A variable horizontal force F = t is applied on theTop of the block as shown in the figure, where is a constant and t is time. The coefficient of friction is so that the block does not slide before toppling.The graph between torque due to normal reaction about end B and time before toppling is start is

A. B.

C. D.

48. A closed cylinder of length l containing a liquid of variable density (x) =0(1 + x) is rotating with constant angular velocity . Find the net force exerted

by the liquid on the axis of rotation. (Take the cylinder to be massless and A =cross sectional area of cylinder)

A. 0A l[1/2 + 1/3l] B. 0A l[1/2 + 2/3l]C. 0A l[1/2 +l] D. 0A l[1/2 + 4/3l]

49. A particle is projected from the mid-point of the line joining two fixed particles each of mass m.If the separation between the fixed particles is l, the minimum velocity of projection of the particleso as to escape is equal to


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A. (Gm)/l B. (Gm)/2lC. (2Gm)/l D. 2(2Gm)/l

50. A particle hanging from a spring stretches it by 1 cm at earths surface. Radius of the earth is 6400Km. At a place 800 Km above the earths surface the same particle will stretch the spring by

A. 1 cm B. 8 cmC. 0.1 cm D. 0.79 cm

51. A circular ring of mass M and radius a is placed in a gravity free space. A small particle of massm placed on the axis of the ring at distance 3a from the centre of the ring is released from rest.The Velocity with which the particle passes through the centre of the ring is

A. (GM)/a B. (GM)/2a[m/M]C. (GM)/2a[M/m] D (GM)/a[M/(M + m)]

52. A satellite is moving round the earth in a circular orbit. The following statement are given.(i) It is moving with a constant velocity.(ii) It suffers no acceleration.(iii) Its angular momentum w.r.t. the earth remains conserved.(iv) Its distance from centre must be equal to 2 earths radius.

The correct option is

A. i and ii are true. B. i and iii and iv are true.

C. only iii is true. D. i and iv are true.53. A light cylindrical vessel is kept on a horizontal surface. Its base area is A. A hole of cross Sectional

area a is made just at its bottom side. The minimum coefficient of friction necessary for sliding of thevessel due to the impact force of the emerging liquid is (a


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A. mg/k[1 d/D] B. mg/k[1 D/d]C. mg/k[1 + d/D] D. None of these.

56. Eight identical droplets falling under gravity in earths atmosphere with terminal velocity v combineTogether to form a single drop. The terminal velocity of the resulting drop will be

A. v B. 2vC. 3v D. 4v

57. Water rises to a height of 10 cm in a capillary tube and mercury falls to depth of 3.42 cm in the samecapillary tube. If the density of mercury is 13.6 g/cc and the angle og contact of mercury and waterare 135 and 0 respectively the ratio of surface tension of water and mercury is

A. 1 : 0.15 B. 1:3C. 1 : 6.5 D. 1.5 : 1

58. An air bubble of radius 5 mm rises through a vat of syrup speed 2 mm/s. If the syrup has a density of1.4x103 Kg/m3, What is its viscosity?

A 1.15 Kg/m-s B. 15 Kg/m-sC. 2.25 Kg/m-s D. 19.05 Kg/m-s

59. n number of water droplets each of radius r, coalesce to form a single drop of radius R. The rise in

Temperatured is

A. 2T/rJ B. 3T/J[1/r 1/R]C. -3T/J D. 3T/J[1/r + 1/R]

60. A smooth spherical ball of radius 1 cm and density 4x103 Kg/m3 is dropped gently in a largeContainer containing viscous liquid of density 2x103 Kg/m3 , and = 0.1 N-s/m2.The distance moved by the ball in t = 0.1 sec after it attains terminal velocity is

A. 4/5 m up B. 4/9 m up.C. 2/3 m down D. 4/9 m down

61. For a stream line flow of water following statement are given belowa) Two streamlines do not intersect each other.b) streamlines must be straight.c) streamlines flow is more likely for liquids with low density and high viscosity.d) streamlines flow is more likely for liquids with high density and low viscosity.


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A. a and b are true. B. a,b and c are trueC. a and c are true D. all are true

62. Water has been filled in a conical vessel fixed on the horizontal surfaceat its base. When a very small hole is made in its curved surface as shownin figure, water will come out in which of the direction shown

A. 1 B. 2C. 3 D. 4

63.When the load on wire is increasing slowly from 2 Kg to 4 Kg, the elongation increases from 0.6 mm to1mm. The work done during this extension of wire is (g 10 m/s)

A.

14 x 10

-3

J B. 0.4 x 10

-3

JC. 8 x 10-2 J D. 10-3 J

64. In the interference of waves from two sources of intensities Io and 4Io the intensity at a point where the phasdifference is is:

A. Io B. 2IoC. 3Io D. 4Io

65.An air column in a pipe , which is closed at one end , will be in resonance with vibrating tuning fork offrequency 264 Hz, if the length of the column is

A. 31.25 B. 62.50C. 93.75 D. 125

66.A policeman on duty detects a drop of 10% in the pitch of the horn of moving car as it crosses him. If velocityof sound is 330 m/s the speed of the car will be

A. 20 m/s B. 17.3 m/sB. 25 m/s D. 27 m/s

67. When two simple harmonic motions of same period , same amplitude having phase difference of 3/2and at right angles to each other are super imposed, the resultant wave form is a

A. circle B. parabolaC. ellipse D. figure of eight


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68. A transverse wave is described by the equation y = yosin 2 (ft x/a). The maximum particle velocity isequal to four times the wave velocity if a is equal to

A. yo/4 B. yo/2C. yo D. 2 yo

69. The amplitude of a wave disturbance propagating in the positive x-direction is given by y = 1/(1 + x)at time t = 0 and by y = 1/[1 +(1 + x)] at t= 2 sec, where x and y are in metres. The shape of the wavedisturbance does not change during the propagation. The velocity of wave is

A. 1 m/s B. 0.5 m/sC. 1.5 m/s D. 2 m/s

70. The displacement y of a particle executing periodic motion is given by y = 4 cos(1/2t)sin(1000t).This expression may be considered as result of the superposition of

A. two waves B. three wavesC. four waves D. five waves

71. A wave pulse on a string has the shape at particular instant as shown in the figure. The wave speed isV= 1 cm/s The point O is a fixed end. The total wave on the string t = 4.5 sec is represented by:

A. B.

B. D.

72. If the amplitude of waves at a distance r from line source is A. The amplitude at a distance 4r will be

A. 2A B. AC. A/2 D. A/4


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73. The pendulum has time period T in air. When it is made to oscillate in water, it acquired a time periodT = 2 T. The specific gravity of the pendulum bob is equal to:

A. 2 B. 2C. 22 D. None of these.

74. A spring is loaded with two blocks m1 & m2, where m1 is rigidly fixed with the springand m2 is just kept on the block m1 as shown in figure. The maximum energy of oscillationthat is possible for the system having the block m2 in contact with m1 is:

A. (m12g2)/2k B. (m22g2)/2kC. [(m1+m2)2g2]/2k D. None of these

75. A particle of mass m is executing oscillations about the origin on the x-axis. Its potential energy is

V(x) = k|x|

3

, where k is positive constant. If the amplitude of oscillation is a, then its time period T isA. proportion to 1/a B. independent of aC. proportion to a D. proportion to a3/2

76. One end of a spring of force constant k is fixed to a vertical wall and the otherto a block of mass m resting on a smooth horizontal surface. There is another wallat a distance xo from the block. The spring is then compressed by 2xo and released.The time taken to strike the wall is:

A. 1/6 (k/m) B. (k/m)C. 2/3(m/k)

D. /4(k/m)

77. A particle moves on x-axis according to the equation x = xosin

2t, the motion is simple harmonic

A. with amplitude xo B. with amplitude 2xoC. with time period (2/) D. with time period (/)

78. A disc of radius R and mass M is pivoted at the rim and is set for small oscillations. If simplependulum has to have the same period as that of the disc, the length of the simple pendulum should be

A. (5/4) R B. (2/3) RC. (3/4) R D. (3/2) R

79.A block of mass m compresses a spring of stiffness k through a distance l/2 asshown in the figure. If the block is not fixed to the spring the period of the motionblock isA. 2(m/k) B. (+4)(m/k)C. (1+)(m/k) D. none of these


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80. A block of mass m rigidly attached with a spring k is compressed through a distance A.If the block is released, the period of oscillation of the block for a complete cycle is equalto

A. 4/3(m/k) B. /2(m/k)C. 2/3(m/k) D. none of this.

81. Time period of a block when suspended from the upper plate of a parallel plate capacitorby a spring of stiffness k is T. When block is uncharged. If a charge q is given to the blockthen the new time period of oscillation will be

A. T B. >TC. = T

82. An object of mass 0.8 Kg is attached to one end of a spring and the system is set

Into simple harmonic motion. The displacement x of the object as a function of timeIs shown in the figure. With the aid of the data, the magnitude of the objects accelerationAt t = 1.0 isA. 0 B. 1.57 m/sB. 0.197 m/s D. 0.157 m/s

83. Two cylinders A and B fitted with massless pistons contain equal amounts of an ideal diatomic gas at300 K. The piston A is free to move, while that of B is held fixed. The same amount of heat is given tothe gas in each cylinder. If the rise in temperature of gas in A is 30 K, then the rise in temperature ofgas in B is:

A. 30 K B. 18 KC. 50 K D. 42 K

84. Two identical containers A and B with frictionless pistons contain the same ideal gas at the sametemperature and the same volume V. The mass of gas A is mA and that in B is mB . The gas in eachcylinder in now allowed to expand to isothermally to the same final volume 2V. The change in thepressure in A and B are found to be 1.5P, respectively. Then,

A. 4 mA = 9 mB B. 2 mA = 3 mBC. 3 mA = 2 mB D. 9 mA = 4 mB

85. Starting with the same initial conditions an ideal gas expands from volume v1 to v2 in three differentWays. The work done by the gas is W1 if the process is purely isothermal, W2 is purely isobaric andW3 if purely adiabatic. Then

A. W2 > W1> W3 B. W2 > W3> W1C. W1 > W2> W3 D. W1 > W3> W2


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86. A monoatomic gas( = 5/3) is suddenly compressed to (1/8) of its volume adiabatically then the pressure ofthe gas will change to

A. 24/5 B. 8C. 40/3 D. 32

87. In a room where temperature is 30 C, a body cools from 61 C to 59 C in 4 minutes. The time taken by thebody to cool from 51C to 49C will be

A. 4 Min B. 6 MinC. 5 Min D. 8 Min

88. The efficiency of an ideal gas with adiabatic exponent for the shown cyclicProcess would be:

A. (2ln2 1)/[ /( -1)] B. (1-2ln2)/[ /( -1)]C. (2ln2 + 1)/[ /( -1)] D. (2ln2 1)/[ /( +1)]

89. Three rods AB,BC and BD of the same length l and cross-sectionalArea A arranged as shown. The end D is immersed in ice whose mass is440 gm. Heat is being supplied at constant rate of 200 cal/sec from end A.Time in which whole ice will melt( Latent heat of fusion of ice is 80 Cal/gm)

A. 40/3 min B. 700 secC. 20/3 min D. Indefinitely lond time[ Given : k(thermal conductivity) = 100 cal/m sec C, A = 10 cm sq. , l = 1 m]

90. A point source S of light is emitting a power P. A sphere of radius r is situatedAt a distance R from the source S(r


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92. A charge Q is uniformly distributed over a non-conducting semi-circular rod of radius R. The potential at thcentre is

A.0 B. Q/(4oR)C. Q/(4o 2R) D. 2Q/(4oR)

93. Two bodies are charged by rubbing one against the other> During the process one becomes positively chargewhile the other becomes negatively charged. Then

A. mass of each body remains unchanged.B. mass of each body changes marginally.C. mass of each body changes slightly and hence the total mass.D. mass of each body changes slightly but the total mass remains the same.

94. An electron is projected from a distance d and with initial velocity u parallel to auniformally charged flat conducting plate as shown. It strikes the plate after travelinga distance l along the direction of projection. The surface charge density of the conducting

plate is equal to

A. 2domu/el B. 2domu/elC. domu/el D. domu/el

95. The ratio of the same time periods of small oscillation of the insulated spring andMass system before and after charging the masses is

A. >= 1 B. >1

C.


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98. A charge Q has to be divided between two solid spheres of radius R which are at distance d from each othe(d >>R). What should be the value of charge , which we should place on sphere so that the force ofattraction between them is maximum?

A. Q/4, 3Q/4 B. Q/3, 2Q/3C. Q/2, Q/2 D. Q/5, 4Q/5

99. An elliptical cavity is carved within a perfect conductor. A positive charge q isPlaced at the centre of the cavity. The points A and B are on the cavity surface. Then,

A. electrical field near A in the cavity must be equal to the electrical field near B in the cavity.B. Charge density at A must be equal to the charge density at BC. Potential at A must be equal to the potential at B.D. Total electric field flux through the surface of cavity is q/o

100. Two identical sheets of metallic foil are separated by d and capacitance of the system is C and charged to apotential difference E. Keeping the charge constant, the separation is increased by lThen, the new capacitance and potential difference will be

A. oA/d, E B. oA/(d+l), EC. oA/(d+l), [1 + l/d]E D. oA/d, [1 + l/d]E

101. A source of constant potential difference is connected across a conductor havingIrregular cross section as shown.

A. Electric field intensity at P is greater than that at Q.B.

Rate of electrons crossing per unit area of cross section P is less than that at Q.C. The rate of generation of heat per unit length at P is greater than at Q.

D. Mean kinetic energy of free electrons at P is greater than that at Q.

102. Current voltage characteristics of two elements A and B are shown below in figs a and b.

Which of the following graphs represents current voltage characteristics for their series combination?


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A. B

B. D.

103. In the given network the batteries getting changed are:

A. 1 and 3B. 1 3 and 5C. 1 and 4D. 1, 2 and 5

104. When a galvanometer is shunted with 4 resistance the deflection is reduced to 1/5. If the galvanometer isfurther shunted with 2 wire the new deflection will be (assuming the main current remains the same)A. 5/13 of the deflection when shunted with 4 only.B. 8/13 of the deflection when shunted with 4 only.C. 3/4 of the deflection when shunted with 4 only.D. 3/13 of the deflection when shunted with 4 only.

105. When the key k is pressed at time t = 0 which of the following statement about the current I, in the resistoAB of the given circuit is true:

A. 2 mA at all time.B. Oscillates between 1 mA and 2 mA.C. 1 mA at all time.D.

At t = 0, I = 2mA and with time it finally reduces to 1 mA.106. Two electric bulbs rated P1 and P2 watt at V volt are connected in series across V volt mains then their tota

power consumption P is

A. (P1 + P2) B. (P1P2)C. P1P2/(P1 + P2) D. (P1 + P2)/P1P2

107. In the given circuit with steady current the potential drop across the capacitorMust be:A. V B. V/2C. V/3 D. 2V/3

108. In the circuit shown in the adjacent figure:

A. the potential at P is -7.5 VB. the potential at Q is -1 VC. the potential at R is 0.D. the potential at S is 0.


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109. The electron in hydrogen atom moves in circular orbit of radius 5 x 10 -11 m with a speed of 0.6 x 106 m/sthen

A.

the frequency of the electron is 6 x 10

15

rev/sB. the electron carries -1.6 x 10-19 C around the loopC. the current in the orbit is 0.96 mAD. the current flow is in the opposite direction to the direction of the motion of electron.

110. A disc of mass m has a charge Q distributed on its surface. It is rotating aboutan XX with a angular velocity . The force acting on the disc is

A. 0 B. RB/C. 2QBR D. none of these

111. A circular loop of wire is carrying a current I (as shown in the figure.)on applying a uniform magnetic field inward perpendicular to the planeof the loop, the loop

A. move along the positive x-direction.B. Move along the negative x-directionC. ContractD. Expand

112. Calculate the magnetic field at distance y from the centre of the axis of a disc ofradius r and uniform surface charge density , if the disc spins with angularvelocity .

A. ()/3[(r-2y)/r-y + 2y] B. ()/2[(r+y)/r+y]C. ()/2[(r+2y)/r+y - 2y] D. (2)/3[(r+2y)/r+y - 2y]

113. An electron moves straight inside a charged parallel plate capacitor of uniform surfaceCharge density . The space between the plates is filled with constant magnetic field ofInduction B. The time of straight line motion of the electron in the capacitor is

A. e/(0lB) B. (0lB)/C. e/(0B) D. 0B/e

114. Three rings each having equal radius R are placed mutually perpendicularTo each other and each having its centre at the origin of co-ordinate system.If the current I is flowing through each ring then the magnitude of the fieldAt the common centre is:


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A. 3 0I/2R B. 0C. (2 - 1)0I/2R D. (3 - 2)0I/2R

115. Consider the plane of the paper to be the vertical plane with direction of g as shownIn the figure. A rod (MM) of mass M and carrying a current I. The rod is suspendedVertically through two insulated spring with constant k at two ends. A uniform magneticfield is applied perpendicular to the plane of the paper such that the potential energy

stored in the spring in equilibrium position is zero. If the rod is slightly displaced in the verticaldirection from the position of equilibrium, then the time period of oscillation is

A. 2(m/k) B. 2(m/2k)C. 2(k/2m) D. 2(m/k).(mg/IlB)

116. A uniform magnetic field of intensity 1T is applied in a circular region of radius 0.1 m, directed into

the plane of paper. A charged particle of mass 5 x 10

-5

Kg and charge q = 5 x 10

-4

C enters thefield with velocity 1/3 m/s making an angle of with radial line of circular region in such a waythat it passes through centre of applied field the angle is

A. 60 B. 30C. 45 D. 90

117. In the shown figure AC and BD are straight lines and CED and AFB are semicircularWith radii r and 4r, respectively. The entire setup is lying in the same plane. If I is thecurrent entering at A what fraction of I will flow in the ACEDB such that resultantmagnetic field at O is zero

A. i/5 B. 4i/5C. 3i/5 D. no current through bigger s.c part

118. A current carrying wire has the configuration shown in the figure.The semi-infinite straight sections each tangent to the same circleare connected by circular arc, of angle along the circumference of the circle, with all sections lying in the same plane. What must be in order for B(magnetic field) to be zero at the centre of the circle.

A. = 1 rad B. = 2 radC. = 3 rad D. = 4 rad


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119. Shown in figure is a small loop that is kept co-axially with the bigger loopIf the slider moves from A to B then

A.

Current flow in both the loops will be in opposite senses.B. Clockwise current in loop 1 and anticlockwise current in loop 2 flowC.No current flows in loop 2D. Clockwise current flows in loop 2

120. A conducting loop is pulled with a constant velocity towards a region of uniformmagnetic field of induction B as shown in the figure, Then the current involved inthe loop is (d >r)

A. clockwise while enteringB. anti clockwise while enteringC.

zero when completely insideD. clockwise while leaving

121. A conducting bar is pulled with a constant speed v on a smooth conducting rail.The region has a steady magnetic field of induction B as shown in the figure. Ifthe speed of the bar is doubled then the rate of heat dissipation will

A. remain constantB.become quarter of the initial valueC.become four foldD.

get doubled

122. A loop is kept so that its centre lies at the origin of the coordinate system. Amagnetic field has the induction B position along the Z axis as shown in thefigure

A.No emf and current will be induced in the loop if it rotates about Z axis.B. Emf is induced but no current flows if the loop is fiber when it rotates about y axis.C. Emf is induced and induced current flows in the loop if the loop is made of cooper and is

rotated about y-axis.D. If the loop moves along z axis with constant velocity no current flows in it.

123. Shown in the figure is an R-L circuit. Just after the key (K) is closed

A. the current in the circuit is zero.B. Potential drop across the resistor is zero.C. Emf developed across the inductor equals the emf of the batteryD.No heat is dissipated in the circuit.


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124. A conductor loop of resistance R and radius r has its center at the origin of theCo-ordinate system in a magnetic field of induction B. When it is rotated about Y-axisthrough 90 , net charge flown in the coil is directly proportional to

A. B B. RC. r D. r

125. The coefficient of mutual inductance of the two coil is 0.5 H. If the current is increased from 2 to 3 Ain 0.01 sec in one of them, then the inclined emf in second coil is:

A. 25 V B. 50 VC. 75 V D. 100 V

126. An ideal choke takes a current of 8 A when connected to an a.c. source of 100 volt and 50 Hz. A pure

resistor under the same conditions takes a current of 10 A. If two are connected in series to an a.c.supply of 100v and 40 Hz, then the current in the series combination of above resistor and inductor is

A. 10 A B. 8 AC. 52 A D. 102 A

127. A resistor R, inductor L and capacitor C are connected in series to a source of frequency n. If theresonant frequency is nr then the current lags behind voltage when

A. n = 0 B. n < nr

C. n = nr D. n > nr128. An AC source of angular frequency is fed across a resistor R and a capacitor C in series. The

current registered is I. If now the frequency of source is changed to /3(but maintaining at the samevoltage), the current in the circuit is found to be halved. The ratio of resistance at the originalfrequency will be:

A. (3/5) B. (5/3)C. 3/5 D. 5/3

129. A beaker containing liquid is placed on a table underneath a microscope which can be moved along avertical scale. The microscope is focused through the liquid onto a mark on the table when thereading on the scale is a. It is next focused on the upper surface of the liquid and the reading is b.More liquid is added and the observation are repeated the corresponding reading are c and d. Therefractive index of the liquid is:

A. (d-b)/(d-c-b+a) B. (b-d)/(d-c-b+a)C. (d-c-b+a)/ (d-b) D. (d-b)/(a+b-c-d)


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130. An observer can see through a pin hole the top end rod of height h, placed asShown in the figure. The beaker height is 3h and its radius h. when the beakeris filled with liquid up to a height 2h, he can see the lower end of the rod. Then

the refractive index of the liquid is

A. 5/2 B. 5/2B.3/2 D. 3/2

131. The focal length of a convex lens of R.I. 1.5 is f when it is placed in air. When it is immersed in aliquid it behaves as a converging lens its focal length becomes xf(x>1). The refractive index ofthe liquid

A. > 3/2 B. 1C. < 3/2 D. All of these

132. The angle of a prism is 30. The ray incident at 60 on one refracting face suffer a diversion of 30. Then thangle of emergence is:A. 0 B. 30C. 60 D. 90

133. In youngs double slit experiment the fringes are displaced by a distance x when a glass plate ofrefractive index 1.5 is introduced in the path of one of the beams. When this plate in replaced byanother plate of the same thickness, the shift of fringes is (3/2)x. The refractive index of the secondplate is

A. 1.75 B. 1.50C. 1.25 D. 1.00

134. The ratio of the intensity at the centre of bright fringe to the intensity at a point one quarter of thedistance between two fringes from the centre isA. 2 B. C. 4 D. 16

135. Among the two interfering monochromatic sources A and B; A is ahead of B in phase by 66. If theobservation be taken from point P, such that PB PA = /4. Then the phase difference between the

wavesfrom A and B reaching P is

A. 156 B. 140C. 136 D. 126

136. P is a small angled prism of angle 3 made of a material of refractive index 1.5. A ray of light is incidentnormally to the mirror as shown in figure. M is a plane mirror. The angle of deviation for the reflectedfrom the mirror M with respect to incident ray is:


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A. 4.5 B. 175.3C. 177 D. 178.5

137. To decrease the cut off wavelength of continuous X-ray by 25%, the potential difference across the X-raytube:

A. must be increased by 100/3 % B. must be decreased by 20%C. must be increased by 25% D. must be decreased by 25%

138. Choose the correct option by matching the following

Column A Column Ba) Maximum kinetic energy of electron emitted i) an integral multiple of h/2

in photoelectric effect is linearly dependent on

b) If number of electrons striking the anode of an ii) the speed of light in vacuum.X-ray tube is increased then

c) X-rays travel with iii) the intensity of emitted X-ray increased

d) Angular momentum of electron in any orbit is iv) the frequency of the incident radiation.

A. a-iv, b-i, c-iii, d-ii B. a-iii, b-ii, c-i, d-ivC. a-i, b-iii, c-ii, d-iv D. a-iv, b-iii, c-ii, d-i

139. The wavelength K X-rays produced by an X-ray tube is 0.76 . The atomic number of anticathode

materialisA. 82 B. 41C. 20 D. 10

140. The ratio of de-Broglie wavelength of an particle to that of a proton being subjected to the sameMagnetic Field so that the radii of their path are equal to each other assuming the field induction vectorB is Perpendicular to the velocity vector of the -particle and the proton is:

A. 1 B. C. D. 2

141. The ratio of de-Broglie wavelength of molecules of hydrogen and helium in two gas jars kept separately attemperature 27C and 127 C respectively, is

A. 2/3 B. 2:3C. 3/4 D. 8/3


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142. A physical quantity x is calculated from the relationX = ab/(cd)

If percentage error in a, b,c and 2%, 1%, 3% and 4% respectively. What is the % error in x?

A. 11% B. 13C. 12% D. 14%

143. A cube has side 1.2 x 10-2 m. Its volume will be recorded as

A. 1.728 x 10-6 m3 B. 1.72 x 10-6 m3C. 1.7 x 10-6 m3 D. 0.72 x 10-6 m3

144. If the force, length and time would have been the fundamental units what would have been the dimensional

formula for mass?A. FL-1T-2 B. FL-1T2C. FLT-2 D. F

145. Power P is given as P = a +bt2 + (c + t3 )/d. If t represents the time then,

Column A Column Ba) Dimension of [a]b) Dimension of [b]

c) Dimension of [c]d) Dimension of [d]

i) [ML T- ]ii) [ML2 T-3]iii)

[M

-1

L

-2

T

-6

]iv) [T3]Which of the following is correct?

A. a-ii, b-i, c-iv and d-iii B. a-i, b-ii, c-iii and d-ivC. a-iv, b-iii, c-ii and d-I D. a-ii, b-i, c-iii and d-iv

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