AMU - Physics - 1998

AMU –PAST PAPERS
PHYSICS- UNSOLVED PAPER - 1998

SECTION – I

 Single Correct Answer Type
 There are five parts in this question. Four choices are given for each part and one of them is

correct. Indicate you choice of the correct answer for each part in your answer-book by

writing the letter (a), (b), (c) or (d) whichever is appropriate

01 Problem

Imagine a light planet resolving around a very massive star in a circular orbit of
radius R with a period of resolution T. If the gravitational force attraction
between the planet and the star is proportional to R-5/2 then:

a. T2 R3.75
b. T2 R3/2
c. T2 R7/2
d. T2 R3

02 Problem
A simple pendulum is executing simple harmonic motion with a time period T. If
the length of the pendulum is increased by 21% the increase in the time period of
the pendulum of increased length is:

a. 52%
b. 30%
c. 21%
d. 10%

03 Problem

A ball is moving horizontal with speed v strikes the bob of a simple pendulum at
rest. The mass of the bob is equal to that of ball. If the collision is elastic, the bob
will rise to height is:

a. v2
2g

v2
b. g

v2
c. 4g

v2
d. 6g

04 Problem

A cup of tea cools from 800C to 600 in one minute The ambient temperature is
300C. In cooing from 600 to 500C. It will take:

a. 80 sec
b. 90 sec
c. 50 sec
d. 60 sec

05 Problem

Two rods of length d1 and d2and coefficient of thermal conductivities K1 and K2
are kept touching each other both have same area of crossection. The equivalent
thermal conductivity is:

d1 d2
d1 d2
a.
K1 K2

b. K1d1 K1d2
d1 d2
c. K1d1 + K2d2
d. K1 + K2

06 Problem

Assume that a piece of bread supplies 200k cal of heat to you. If your weight is 60
kg and efficiency is 40% then how much you can climb up by using this energy?

a. 170 m
b. 750 m
c. 670 m
d. 570 m

07 Problem

Equal charges q are placed at the four corners A,B,C,D of a square of length a, the
magnitude of the force on the charge at D will be :

a. 1 q2
2
2 4 0 a2

1 2 2 q2
b.
2 4 0 a2

4q2
c. 4 0 a2

3q2
d. 4 0 a2

08 Problem

The two fixed changes +4q and +q are at a distance r apart. At what point
between these charges +q must be placed to keep in a equilibrium?

2r
a. 3

3r
b. 2

4r
c. 3

3r
d. 4

09 Problem

The magnetic flux density B at a distance r from a long straight wire carrying a
steady current varies with distance r as shown in :

a.

b.

c.

d.

10 Problem

In a Young’s double slit experiment the interference pattrerns is found to have
an intensity ratio between bright and dark fringes a 16:9. It implies that the
amplitude ratio of the interfering rays is:

a. 4:3
b. 16:9
c. 9:1
d. 1:7

11 Problem

The magnifying power of an astronomical telescope for relaxed eye is 8 and
length of the telescope is 18 cm. If fo and fe br the focal lengths of the
objective and the eyepiece, thus:

a. f o=3cm and f e=4cm
b. f o=20 and f e=2cm
c. f o=12 and f e=6cm
d. f o16 and f e=2cm

12 Problem

The material of a permanent magnet should have,

a. High coercivity and low retentivity
b. Low coercivity and high retentivity
c. Low coercivity and high retentivity
d. High coercivity and high retentivity

13 Problem

Speed of light in a medium of refractive index 1.4 is (speed of light in
vacuum=3x108 m/sec):

a. 2.64x108m/sec
b. 2.52x108sec
c. 3x108m/s
d. 2.14x108 m/sec

14 Problem

If we want to produce the electromagnetic waves of wavelength 500 km by
mechanical means, the charge should oscillate with a frequency of:

a. 187 cycles/speed
b. 600 cycles/sec
c. 550 cycles/sec
d. 575 cycles/sec

15 Problem

Out of Bi210,U235,U238 and Pu239 the fissionable materials are:

a. U235,Pu239
b. U238,Pu239
c. U235,Pu238
d. U235,Pu235

16 Problem

The maximum kinetic energy of photoelectrons emitted from a surface when
photons of energy 6 eV fall on a is 4 eV. the stopping potential is :

a. 10 V
b. 6 V
c. 2 V
d. 4 V

17 Problem

A small solid ball is released in a viscous liquid. The velocity of ball is given by

a. Curve D
b. Curve C
c. Curve B
d. Curve A

18 Problem

The displacement time graph of an object is shown in figure. Which part of graph
represents accelerated motion :

a. CD
b. BC
c. AB
d. OA

19 Problem

A mass of 200 g when suspended from a massless spring extends it by 10 cm. A
lump of plasticine of mass 200 g is dropped from rest onto a massless pan from a
height of a 40 cm as shown in figure. As a result the pan moves downwards
through a maximum distance of :

a. 40 cm
b. 30 cm
c. 20 cm
d. 10 cm

20 Problem

An open topped rail road car of mass M has an initial velocity v0 along a straight
horizontal frictionless track. It suddenly starts raising at time t = 0. The rain drops
fall vertically with velocity u and add a mass m kg/sec of water. The velocity of
car after t second will be (assuming that it is not completely filled with water) :

u
a. v0 m
M

Mv0
b. M mt

Mv0 t
c. M ut

mut
v0
M ut
d.

21 Problem

Two bodies of mass moving with equal kinetic energies. The ratio of the
magnitude of their respective linear momenta is :

a. 9 : 7
b. 9 : 1
c. 1 : 6
d. 1 : 3

22 Problem

A particle of mass m is moving in a circular path of constant radius r such that its
centripetal acceleration as it varying with time to as ac = k2rt2, where k is
constant. The power delivered to a prticle by the forces acting on it is

a. Zero
1
b. 3
mk4r2t5
c. 2 mk4r2t5
d. mk2r2t

23 Problem

A whistle of frequency 500 Hz tied to the end of spring of length 1.2 m revolves
at 400 rev./minute. A listener standing some distance away in the plane of
rotation of whistle, hears frequency in the range (speed of second = 34 m/s) :

a. 436 to 486
b. 426 to 584
c. 436 to 586
d. 426 to 586

24 Problem

the maximum electric field that can be held in air without producing Q
ionization of air is 107 V/m. The maximum potential therefore, to which a
conducting sphere of radius 0.10 m can be charged in air is :

a. 109 V
b. 018 V
c. 107 V
d. 106 V

25 Problem

In the fig given below, find the resistance between parts A and B. both the circles
and the diameter are made of uniform wire of resistance r ohm per metre. The
length AB is 2 metre :

a. 0.88 r
b. 14.56 r
2r
c. 3
d. 2 r

26 Problem

In the circuit the cells E1 and E2 have emf 48 and 8 V and internal resistances 0.5
and 1.0 respectively. Then the potential difference across cells E1 and E2
will be :

a. 4.25 V, 4.25 V
b. 3.75 V, 3.75 V
c. 4.25 V, 7.5 V
d. 3.75 V, 7.5 V

27 Problem

In producing chlorine through electrolysis 100 kW power at 125 V is being
consumed. How much chlorine per minute is liberated ?
(E.C.E of chlorine = 0.36 x 10-6 kg/C)

a. 37 x 10-3 kg
b. 7.61 x 10-3 kg
c. 27.61 x 10-3 kg
d. 17.61 x 10-3 kg

28 Problem

How much energy will approximately be released if all the atom of 1 kg of
deuterium could undergo fusion ? Assume in the fusion of deuterium 0.1%
mass is converted into energy :

a. 8 x 1023 MeV
b. 6 x 1027 cal
c. 9 x 1013 J
d. 2 x 107 kWh

29 Problem

A vessel of depth 2d cam is half filled with a liquid of refractive index 1 and the
upper half with a liquid of refractive index . The apparent depth of the vessel
2

seen perpendicular is :

1
a. 2d
1 / 2

1
2d
b. 1
1
2

1 1
c. d
1 2

d. d
1 2

2

30 Problem

The absolute refractive indices of glass and water are respectively. Then the
3 4
and refractive index of glass with respect to water will be :
2 3

a. 7/6
b. 8/9
c. 9/8
d. 4/3

31 Problem

A wire of magnetic moment M and pole strength m is cut in to four pieces. If one
of the part is bent in the form of a semcircle. Its magnetic moment and pole
strength, respectively are :

a. M m
4

m
b. 4 ,m

m m
c. 4 ,4

M
d. 2 ' m

32 Problem

The truth table of a logic gate is given as

a. NOR gate
b. AND gate
c. NAND gate
d. XOR gate

33 Problem

Energy band gap in a semiconductor is of the order of :

a. 1 eV
b. 0.1eV
c. 0.5 eV
d. none of these

34 Problem

A p type semiconductor has :

a. More protons as compared to electrons
b. More protons as compared to electrons
c. More holes as compared to electrons
d. More electron as compared to holes

35 Problem

Fusion reaction take place at about :

a. 3 x 106 K
b. 3 x 104 K
c. 3 x 103 K
d. 3 x 102 K

36 Problem

The unit of 0
([permeability of free space]) is :

a. w b/m2
b. tesla
c. Am2
d. Henry/metre

37 Problem

The temperature coefficient of resistance of material of wire which has a
resistance of 140 at 1600C and 240 at 4600 C is :

a. 0.000384/0C
b. 0.000284/0C
c. 0.000184/0C
d. none of these

38 Problem

An aircraft with a wing span of 20 m flies at a horizontal speed of 360 km/h in a
region where the vertical component of the earth field is 5 x 10-5 tesla. The
potential difference between the tips of the wing will be :

a. 0.30 eV
b. 0.20 V
c. 0.10 V
d. 0.15 V

39 Problem

The magnitude of flux linked with the circuit of resistance 2k varies with t
second according to equation = 5t2 – 4t + 12 The induced current in the circuit
at t = 0.2 second is :

a. 2 A
b. 1 A
c. 2 mA
d. 1 m A

40 Problem

The work done in turning a magnet of magnetic moment M by an angle of 900
from the meridian is n times. The corresponding work done to turn it through an
angle of 600 where n is given by :

a. 1
b. 1/4
c. 1/2
d. 2

41 Problem

The diver at a depth of 12 cm in water ( = 4/3) sees the sky in a cone of semi
vertical angle :

a. 900
3
b. sin-1 4
4
c. tan-4 3
4
d. sin-1 3

42 Problem

Angle of prism is A and its one surface is silvered, light rays falling at an angle of
incidence 2 a on first surface return back through the same path after suffering
reflections at second silvered surface refractive index of the material of the
prism will be :

a. tan A
1
b. 2
cos A
c. 2 sin A
d. 2 cos A

43 Problem

A glass tube 1.0 m long is filled with water. The water can be drained out slowly
at the bottom of the tube. If a vibrating tuning fork of frequency 500 cycles/sec is
brought at the upper end of the tube and the velocity of sound is 330 m/s, then
the total number of resonance obtained will be :

a. 1
b. 2
c. 3
d. 7

44 Problem

A stone is dropped into a well and its splash is heard at the mouth of the well
after an internal of 1.45 second. The depth of the well is (Given that velocity of
send in air at room temperature is equal to 332 m/s) :

a. 9.9 m
b. s 19.9 m
c. 29.9 m
d. none of these

45 Problem

The velocity of sound in a gas at pressure P and density d is :

p
a.
d

p
b. d

p
c. d

2p
d. d

46 Problem

Mud houses are colder in summer and warmer in winter becase of :

a. clay is a good conductor of heat
b. clay is bad conductor of heat as compared of with wood and bricks
c. clay is neither good conductor nor bad conductor of heat
d. none of these

47 Problem

One gram of water (volume 1 cm3) becomes 1671 cm3 of steam when boiled at
a pressure of one atmosphere. The latent heat of vaporization is 540 cal/g. The
external work done and increase in internal energy will be (1 atmosphere =
1.013 x 105 N/m2) :

a. 40.3 cal, 499.7 cal
b. 50.3 cal, 599.7 cal
c. 55.3 cal, 540.7 cal
d. none of these

48 Problem

The radius of first Bohr’s orbit of electron in hydrogen atom is :
(e = 1.6 x 10-19 C, m = 9.1 x 10-31 kg, h = 6.6 x 10-34 Js)

a. 0.53 Å
b. 5.3 Å
c. 0.53 m
d. 53 Å

49 Problem

Which one of following series lies in ultra violet region ?

a. Balmer series
b. Bracket series
c. Paschen series
d. Lyman series

50 Problem

Bi210 has a half life of 5 days the time taken for seven/eight of a sample to decay
is :

a. 15 days
b. 20 days
c. 10 days
d. 3.4 days

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AMU - Physics - 1998

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