JEE MAIN - Physics (2002)

1
The energy band gap is maximum in
答え
(C)
insulator
2
Which of the following are not electromagnetic waves?
答え
(C)
$$\beta $$-rays
3
If two mirrors are kept at $${60^ \circ }$$ to each other, then the number of images formed by them is
答え
(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
答え
(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
答え
(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).
答え
(B)
$$It$$
7
If a current is passed through a spring then the spring will
答え
(B)
compress
8
If in the circuit, power dissipation is $$150W,$$ then $$R$$ is
答え
(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
答え
(A)
$$1$$
10
If an electron and a proton having same momentum enter perpendicular to a magnetic field, then
答え
(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
答え
(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 $$1$$?
答え
(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
答え
(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
答え
(B)
$$2A$$
15
An astronomical telescope has a large aperture to
答え
(B)
have high resolution
16
Electromagnetic waves are transverse in nature is evident by
答え
(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 :
答え
(D)
$$5:4$$
18
Which of the following is used in optical fibres?
答え
(A)
total internal reflection
19
The inductance between $$A$$ and $$D$$ is
答え
(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
答え
(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
答え
(C)
$$3.4$$ $$eV$$
22
At absolute zero, Si acts as
答え
(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
答え
(C)
$$2:1$$
24
Formation of covalent bonds in compounds exhibits
答え
(A)
wave nature of electron
25
By increasing the temperature, the specific resistance of a conductor and a semiconductor
答え
(C)
increases, decreases
26
Capacitance (in $$F$$) of a spherical conductor with radius $$1$$ $$m$$ is
答え
(A)
$$1.1 \times {10^{ - 10}}$$
27
Moment of inertia of a circular wire of mass $$M$$ and radius $$R$$ about its diameter is
答え
(A)
$${{M{R^2}} \over 2}$$
28
The escape velocity of a body depends upon mass as
答え
(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
答え
(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?
答え
(C)
$$4$$
31
Infrared radiation is detected by
答え
(B)
pyrometer
32
Heat given to a body which raises its temperature by $${1^ \circ }C$$ is
答え
(B)
thermal capacity
33
Which of the following is more close to a black body?
答え
(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
答え
(C)
decrease
35
Cooking gas containers are kept in a lorry moving with uniform speed. The temperature of the gas molecules inside will
答え
(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 $${47^ \circ }C?$$
答え
(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
答え
(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
答え
(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
答え
(B)
$$T/\sqrt n $$
40
In a simple harmonic oscillator, at the mean position
答え
(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
答え
(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
答え
(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
答え
(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
答え
(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
答え
(B)
$$y = - a\,\sin \,\left( {\omega t + kx} \right)$$
46
When temperature increases, the frequency of a tuning fork
答え
(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
答え
(A)
$$0.1$$ $$V$$
48
If there are $$n$$ capacitors in parallel connected to $$V$$ volt source, then the energy stored is equal to
答え
(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
答え
(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
答え
(D)
$$ - Q/4$$
51
If an ammeter is to be used in place of a voltmeter, then we must connect with the ammeter a
答え
(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
答え
(C)
$$mgR$$
53
Identify the pair whose dimensions are equal
答え
(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
答え
(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
答え
(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?
答え
(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
答え
(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
答え
(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
答え
(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
答え
(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 $$C$$?
答え
(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 :
答え
(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
答え
(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?
答え
(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
答え
(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
答え
(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)
答え
(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?
答え
(D)
zero
69
If suddenly the gravitational force of attraction between Earth and a satellite revolving around it becomes zero, then the satellite will
答え
(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
答え
(D)
$${{GMm} \over {6R}}$$