JEE MAIN - Physics (2002)

1
The energy band gap is maximum in
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(C)
insulator
2
Which of the following are not electromagnetic waves?
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(C)
$$\beta $$-rays
3
If two mirrors are kept at $${60^ \circ }$$ to each other, then the number of images formed by them is
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(A)
$$5$$
4
A wire when connected to $$220$$ $$V$$ mains supply has power dissipation $${P_1}.$$ Now the wire is cut into two equal pieces which are connected in parallel to the same supply. Power dissipation in this case is $${P_2}.$$ Then $${P_2}:{P_1}$$ is
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(B)
$$4$$
5
If $${\theta _1},$$ is the inversion temperature, $${\theta _n}$$ is the neutral temperature, $${\theta _c}$$ is the temperature of the cold junction, then
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(C)
$${{{\theta _i} + {\theta _C}} \over 2} = {\theta _n}$$
6
The mass of product liberated on anode in an electrochemical cell depends on (where $$t$$ is the time period for which the current is passed).
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(B)
$$It$$
7
If a current is passed through a spring then the spring will
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(B)
compress
8
If in the circuit, power dissipation is $$150W,$$ then $$R$$ is
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(B)
$$6\,\Omega $$
9
If in a circular coil $$A$$ of radius $$R,$$ current $$I$$ is flowing and in another coil $$B$$ of radius $$2R$$ a current $$2I$$ is flowing, then the ratio of the magnetic fields $${B_A}$$ and $${B_B}$$, produced by them will be
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(A)
$$1$$
10
If an electron and a proton having same momentum enter perpendicular to a magnetic field, then
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(A)
curved path of electron and proton will be same (ignoring the sense of revolution)
11
The time period of a charged particle undergoing a circular motion in a uniform magnetic field is independent of its
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(A)
speed
12
Wires $$1$$ and $$2$$ carrying currents $$i{}_1$$ and $$i{}_2$$ respectively are inclined at an angle $$\theta $$ to each other. What is the force on a small element $$dl$$ of wire $$2$$ at a distance of $$r$$ from wire $$1$$ (as shown in figure) due to the magnetic field of wire $$1$$?
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(C)
$${{{\mu _0}} \over {2\pi r}}{i_1}{i_2}\,dl\,\cos \,\theta $$
13
The power factor of $$AC$$ circuit having resistance $$(R)$$ and inductance $$(L)$$ connected in series and an angular velocity $$\omega $$ is
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(B)
$$R/{\left( {{R^2} + {\omega ^2}{L^2}} \right)^{1/2}}$$
14
In a transformer, number of turns in the primary coil are $$140$$ and that in the secondary coil are $$280.$$ If current in primary coil is $$4A,$$ then that in the secondary coil is
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(B)
$$2A$$
15
An astronomical telescope has a large aperture to
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(B)
have high resolution
16
Electromagnetic waves are transverse in nature is evident by
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(A)
polarization
17
Wavelength of light used in an optical instrument are $${\lambda _1} = 4000\mathop A\limits^ \circ $$ and $${\lambda _2} = 5000\mathop A\limits^ \circ ,$$ then ratio of their respective resolving powers (corresponding to $${\lambda _1}$$ and $${\lambda _2}$$ ) is :
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(D)
$$5:4$$
18
Which of the following is used in optical fibres?
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(A)
total internal reflection
19
The inductance between $$A$$ and $$D$$ is
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(D)
$$1$$ $$H$$
20
A conducting square loop of side $$L$$ and resistance $$R$$ moves in its plane with a uniform velocity $$v$$ perpendicular to one of its sides. A magnetic induction $$B$$ constant in time and space, pointing perpendicular and into the plane at the loop exists everywhere with half the loop outside the field, as shown in figure. The induced $$emf$$ is
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(D)
$$vBL$$
21
If $$13.6$$ $$eV$$ energy is required to ionize the hydrogen atom, then the energy required to remove an electron from $$n=2$$ is
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(C)
$$3.4$$ $$eV$$
22
At absolute zero, Si acts as
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(C)
insulator
23
Sodium and copper have work functions $$2.3$$ $$eV$$ and $$4.5$$ $$eV$$ respectively. Then the ratio of the wavelengths is nearest to
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(C)
$$2:1$$
24
Formation of covalent bonds in compounds exhibits
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(A)
wave nature of electron
25
By increasing the temperature, the specific resistance of a conductor and a semiconductor
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(C)
increases, decreases
26
Capacitance (in $$F$$) of a spherical conductor with radius $$1$$ $$m$$ is
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(A)
$$1.1 \times {10^{ - 10}}$$
27
Moment of inertia of a circular wire of mass $$M$$ and radius $$R$$ about its diameter is
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(A)
$${{M{R^2}} \over 2}$$
28
The escape velocity of a body depends upon mass as
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(A)
$${m^0}$$
29
A spring of force constant $$800$$ $$N/m$$ has an extension of $$5$$ $$cm.$$ The work done in extending it from $$5$$ $$cm$$ to $$15$$ $$cm$$ is
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(B)
$$8J$$
30
One end of a mass-less rope, which passes over a mass-less and friction-less pulley $$P$$ is tied to a hook $$C$$ while the other end is free. Maximum tension that the rope can bear is $$360$$ $$N.$$ With what value of maximum safe acceleration (in $$m{s^{ - 2}}$$) can a man of $$60$$ $$kg$$ climb on the rope?
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(C)
$$4$$
31
Infrared radiation is detected by
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(B)
pyrometer
32
Heat given to a body which raises its temperature by $${1^ \circ }C$$ is
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(B)
thermal capacity
33
Which of the following is more close to a black body?
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(A)
black board paint
34
If mass-energy equivalence is taken into account, when water is cooled to form ice, the mass of water should
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(C)
decrease
35
Cooking gas containers are kept in a lorry moving with uniform speed. The temperature of the gas molecules inside will
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(C)
remain same
36
At what temperature is the $$r.m.s$$ velocity of a hydrogen molecule equal to that of an oxygen molecule at $${47^ \circ }C?$$
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(D)
$$20$$ $$K$$
37
Two spheres of the same material have radii $$1$$ $$m$$ and $$4$$ $$m$$ and temperatures $$4000$$ $$K$$ and $$2000$$ $$K$$ respectively. The ratio of the energy radiated per second by the first sphere to that by the second is
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(A)
$$1:1$$
38
1 mole of a gas with $$\gamma = 7/5$$ is mixed with $$1$$ mole of a gas with $$\gamma = 5/3,$$ then the value of $$\gamma $$ for the resulting mixture is
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(C)
$$3/2$$
39
If a spring has time period $$T,$$ and is cut into $$n$$ equal parts, then the time period of each part will be
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(B)
$$T/\sqrt n $$
40
In a simple harmonic oscillator, at the mean position
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(C)
kinetic energy is maximum, potential energy is minimum
41
A child swinging on a swing in sitting position, stands up, then the time period of the swing will
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(B)
decrease
42
length of a string tied to two rigid supports is $$40$$ $$cm$$. Maximum length (wavelength in $$cm$$) of a stationary wave produced on it is
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(B)
$$80$$
43
A tuning fork arrangement (pair) produces $$4$$ beats/sec with one fork of frequency $$288$$ $$cps.$$ A little wax is placed on the unknown fork and it then produces $$2$$ beats/sec. The frequency of the unknown fork is
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(B)
$$292$$ $$cps$$
44
Tube $$A$$ has bolt ends open while tube $$B$$ has one end closed, otherwise they are identical. The ratio of fundamental frequency of tube $$A$$ and $$B$$ is
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(C)
$$2:1$$
45
A wave $$y=a$$ $$\sin \left( {\omega t - kx} \right)$$ on a string meets with another wave producing a node at $$x=0.$$ Then the equation of the unknown wave is
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(B)
$$y = - a\,\sin \,\left( {\omega t + kx} \right)$$
46
When temperature increases, the frequency of a tuning fork
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(B)
decreases
47
On moving a charge of $$20$$ coulomb by $$2$$ $$cm,$$ $$2$$ $$J$$ of work is done, then the potential differences between the points is
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(A)
$$0.1$$ $$V$$
48
If there are $$n$$ capacitors in parallel connected to $$V$$ volt source, then the energy stored is equal to
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(B)
$${1 \over 2}nC{V^2}$$
49
A charged particle $$q$$ is placed at the centre $$O$$ of cube of length $$L(ABCDEFGH).$$ Another same charge $$q$$ is placed at a distance $$L$$ from $$O$$. Then the electric flux through $$ABCD$$ is
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(B)
zero
50
If a charge $$q$$ is placed at the center of the line joining two equal charges $$Q$$ such that the system is in equilibrium then the value of $$q$$ is
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(D)
$$ - Q/4$$
51
If an ammeter is to be used in place of a voltmeter, then we must connect with the ammeter a
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(C)
high resistance in series
52
The kinetic energy needed to project a body of mass $$m$$ from the earth surface (radius $$R$$) to infinity is
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(C)
$$mgR$$
53
Identify the pair whose dimensions are equal
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(A)
torque and work
54
A ball whose kinetic energy E, is projected at an angle of $$45^\circ $$ to the horizontal. The kinetic energy of the ball at the highest point of its height will be
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(C)
$${E \over 2}$$
55
From a building two balls A and B are thrown such that A is thrown upwards and B downwards ( both vertically with the same speed ). If v_A and v_B are their respective velocities on reaching the ground, then
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(B)
$${v_A} = {v_B}$$
56
If a body looses half of its velocity on penetrating $$3$$ $$cm$$ in a wooden block, then how much will it penetrate more before coming to rest?
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(A)
$$1$$ $$cm$$
57
A lift is moving down with acceleration $$a.$$ A man in the lift drops a ball inside the lift. The acceleration of the ball as observed by the man in the lift and a man standing stationary on the ground are respectively
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(C)
$$g-a, g$$
58
When forces $${F_1},\,\,{F_2},\,\,{F_3}$$ are acting on a particle of mass $$m$$ such that $${F_2}$$ and $${F_3}$$ are mutually perpendicular, then the particle remains stationary. If the force $${F_1}$$ is now removed then the acceleration of the particle is
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(A)
$${F_1}/m$$
59
Two forces are such that the sum of their magnitudes is $$18$$ $$N$$ and their resultant is $$12$$ $$N$$ which is perpendicular to the smaller force. Then the magnitudes of the forces are
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(B)
$$13N,$$ $$5N$$
60
A light string passing over a smooth light pulley connects two blocks of masses $${m_1}$$ and $${m_2}$$ (vertically). If the acceleration of the system is $$g/8$$, then the ratio of the masses is
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(B)
$$9:7$$
61
Three identical blocks of masses $$m=2$$ $$kg$$ are drawn by a force $$F=10.2$$ $$N$$ with an acceleration of $$0.6$$ $$m{s^{ - 2}}$$ on a frictionless surface, then what is the tension (in $$N$$) in the string between the blocks $$B$$ and $$C$$?
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(D)
$$7.8$$
62
Speeds of two identical cars are $$u $$ and $$4$$$$u $$ at the specific instant. The ratio of the respective distances in which the two cars are stopped from that instant is :
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(D)
$$1:16$$
63
A cylinder of height $$20$$ $$m$$ is completely filled with water. The velocity of efflux of water (in $$m{s^{ - 1}}$$) through a small hole on the side wall of the cylinder near its bottom is
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(B)
$$20$$
64
Initial angular velocity of a circular disc of mass $$M$$ is $${\omega _1}.$$ Then two small spheres of mass $$m$$ are attached gently to diametrically opposite points on the edge of the disc. What is the final angular velocity of the disc?
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(C)
$$\left( {{M \over {M + 4m}}} \right)\,\,{\omega _1}$$
65
Two identical particles move towards each other with velocity $$2v$$ and $$v$$ respectively. The velocity of center of mass is
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(C)
$$v/2$$
66
The minimum velocity (in $$m{s^{ - 1}}$$) with which a car driver must traverse a flat curve of radius 150 m and coefficient of friction $$0.6$$ to avoid skidding is
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(B)
$$30$$
67
A solid sphere, a hollow sphere and a ring are released from top of an inclined plane (frictionless) so that they slide down the plane. Then maximum acceleration down the plane is for (no rolling)
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(D)
all same
68
A particle of mass $$m$$ moves along line PC with velocity $$v$$ as shown. What is the angular momentum of the particle about P?
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(D)
zero
69
If suddenly the gravitational force of attraction between Earth and a satellite revolving around it becomes zero, then the satellite will
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(B)
move tangentially to the original orbit with the same velocity
70
Energy required to move a body of mass $$m$$ from an orbit of radius $$2R$$ to $$3R$$ is
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(D)
$${{GMm} \over {6R}}$$