JEE MAIN - Physics (2004)

1
An electromagnetic wave of frequency $$v=3.0$$ $$MHz$$ passes from vacuum into a dielectric medium with permittivity $$ \in = 4.0.$$ Then
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(A)
wave length is halved and frequency remains unchanged
2
The maximum number of possible interference maxima for slit-separation equal to twice the wavelength in Young's double-slit experiment, is :
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(B)
five
3
The work function of a substance is $$4.0$$ $$eV.$$ The longest wavelength of light that can cause photo-electron emission from this substance is approximately.
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(A)
$$310$$ $$nm$$
4
A radiation of energy $$E$$ falls normally on a perfectly reflecting surface. The momentum transferred to the surface is
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(B)
$$2E/c$$
5
According to Einstein's photoelectric equation, the plot of the kinetic energy of the emitted photo electrons from a metal $$Vs$$ the frequency, of the incident radiation gives as straight the whose slope
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(D)
is the same for the all metals and independent of the intensity of the radiation
6
The binding energy per nucleon of deuteron $$\left( {{}_1^2\,H} \right)$$ and helium nucleus $$\left( {{}_2^4\,He} \right)$$ is $$1.1$$ $$MeV$$ and $$7$$ $$MeV$$ respectively. If two deuteron nuclei react to form a single helium nucleus, then the energy released is
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(A)
$$23.6\,\,MeV$$
7
An $$\alpha $$-particle of energy $$5$$ $$MeV$$ is scattered through $${180^ \circ }$$ by a fixed uranium nucleus. The distance of closest approach is of the order of
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(A)
$${10^{ - 12}}\,cm$$
8
A piece of copper and another of germanium are cooled from room temperature to $$77K,$$ the resistance of
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(D)
copper decreases and germanium increases
9
The manifestation of band structure in solids is due to
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(B)
Pauli's exclusion principle
10
The angle of incidence at which reflected light is totally polarized for reflection from air to glass (refractive index $$n$$) is :
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(D)
$${\tan ^{ - 1}}\left( n \right)$$
11
When $$p$$-$$n$$ junction diode is forward biased then
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(A)
both the depletion region and barrier height are reduced
12
A current $$i$$ ampere flows along an infinitely long straight thin walled tube, then the magnetic induction at any point inside the tube is
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(B)
zero
13
Four charges equal to -$$Q$$ are placed at the four corners of a square and a charge $$q$$ is at its center. If the system is in equilibrium the value of $$q$$ is
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(B)
$${Q \over 4}\left( {1 + 2\sqrt 2 } \right)$$
14
A charged oil drop is suspended in a uniform field of $$3 \times {10^4}$$ $$v/m$$ so that it neither falls nor rises. The charge on the drop will be (Take the mass of the charge $$ = 9.9 \times {10^{ - 15}}\,\,kg$$ and $$g = 10\,m/{s^2}$$)
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(C)
$$3.3 \times {10^{ - 18}}\,C$$
15
An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii are in the ratio of $${4 \over 3}$$ and $${2 \over 3}$$, then the ratio of the current passing through the wires will be
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(B)
$$1/3$$
16
The resistance of the series combination of two resistances is $$S.$$ When they are jointed in parallel the total resistance is $$P.$$ If $$S = nP$$ then the Minimum possible value of $$n$$ is
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(C)
$$4$$
17
The total current supplied to the circuit by the battery is
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(A)
$$4A$$
18
Thermistors are usually made of
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(A)
metal oxides with high temperature coefficient of resistivity
19
Time taken by a $$836$$ $$W$$ heater to heat one litre of water from $$10{}^ \circ C$$ to $$40{}^ \circ C$$ is
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(A)
$$150$$ $$s$$
20
In a meter bridge experiment null point is obtained at $$20$$ $$cm$$, from one end of the wire when resistance $$X$$ is balanced against another resistance $$Y.$$ If $$X < Y$$, then where will be the new position of the null point from the same end, if one decides to balance a resistance of $$4$$ $$X$$ against $$Y$$
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(C)
$$50$$ $$cm$$
21
The thermo $$emf$$ of a thermocouple varies with temperature $$\theta $$ of the hot junction as $$E = a\theta + b{\theta ^2}$$ in volts where the ratio $$a/b$$ is $${700^ \circ }C.$$ If the cold junction is kept at $${0^ \circ }C,$$ then the neutral temperature is
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(D)
No neutral temperature is possible for this termocouple.
22
The electrochemical equivalent of a metal is $${3.35109^{ - 7}}$$ $$kg$$ per Coulomb. The mass of the metal liberated at the cathode when a $$3A$$ current is passed for $$2$$ seconds will be
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(C)
$$19.8 \times {10^{ - 7}}\,kg$$
23
A material $$'B'$$ has twice the specific resistance of $$'A'.$$ A circular wire made of $$'B'$$ has twice the diameter of a wire made of $$'A'$$. Then for the two wires to have the same resistance, the ratio $${l \over B}/{l \over A}$$ of their respective lengths must be
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(D)
$$2$$
24
The Kirchhoff's first law $$\left( {\sum i = 0} \right)$$ and second law $$\left( {\sum iR = \sum E} \right),$$ where the symbols have their usual meanings, are respectively based on
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(D)
conservation of charge, conservation of energy
25
Curie temperature is the temperature above which
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(A)
a ferromagnetic material becomes paramagnetic
26
A long wire carries a steady current. It is bent into a circle of one turn and the magnetic field at the centre of the coil is $$B.$$ It is then bent into a circular loop of $$n$$ turns. The magnetic field at the center of the coil will be
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(B)
$${n^2}\,B$$
27
The magnetic field due to a current carrying circular loop of radius $$3$$ $$cm$$ at a point on the axis at a distance of $$4$$ $$cm$$ from the centre is $$54\,\mu T.$$ What will be its value at the center of loop?
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(C)
$$250\,\mu T$$
28
The length of a magnet is large compared to its width and breadth. The time period of its oscillation in a vibration magnetometer is $$2s.$$ The magnet is cut along its length into three equal parts and these parts are then placed on each other with their like poles together. The time period of this combination will be
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(B)
$${2 \over 3}\,\,s$$
29
Two long conductors, separated by a distance $$d$$ carry current $${I_1}$$ and $${I_2}$$ in the same direction. They exert a force $$F$$ on each other. Now the current in one of them is increased to two times and its direction is reversed. The distance is also increased to $$3d$$. The new value of the force between them is
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(A)
$$ - {{2F} \over 3}$$
30
The materials suitable for making electromagnets should have
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(B)
low retentivity and low coercivity
31
In an $$LCR$$ series $$a.c.$$ circuit, the voltage across each of the components, $$L,C$$ and $$R$$ is $$50V$$. The voltage across the $$L.C$$ combination will be :
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(D)
$$0$$ $$V$$ (zero)
32
Alternating current can not be measured by $$D.C.$$ ammeter because
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(A)
Average value of current for complete cycle is zero
33
A coil having $$n$$ turns and resistance $$R\Omega $$ is connected with a galvanometer of resistance $$4R\Omega .$$ This combination is moved in time $$t$$ seconds from a magnetic field $${W_1}$$ weber to $${W_2}$$ weber. The induced current in the circuit is
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(B)
$$ - {{n\left( {{W_2} - {W_1}} \right)} \over {5\,\,Rt}}$$
34
In a uniform magnetic field of induction $$B$$ a wire in the form of a semicircle of radius $$r$$ rotates about the diameter of the circle with an angular frequency $$\omega .$$ The axis of rotation is perpendicular to the field. If the total resistance of the circuit is $$R,$$ the mean power generated per period of rotation is
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(B)
$${{{{\left( {B\pi {r^2}\omega } \right)}^2}} \over {8R}}$$
35
In a $$LCR$$ circuit capacitance is changed from $$C$$ to $$2$$ $$C$$. For the resonant frequency to remain unchaged, the inductance should be changed from $$L$$ to
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(A)
$$L/2$$
36
A metal conductor of length $$1$$ $$m$$ rotates vertically about one of its ends at angular velocity $$5$$ radians per second. If the horizontal component of earth's magnetic field is $$0.2 \times {10^{ - 4}}T,$$ then the $$e.m.f.$$ developed between the two ends of the conductor is
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(B)
$$50\mu V$$
37
A plano convex lens of refractive index $$1.5$$ and radius of curvature $$30$$ $$cm$$. Is silvered at the curved surface. Now this lens has been used to form the image of an object. At what distance from this lens an object be placed in order to have a real image of size of the object
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(C)
$$20$$ $$cm$$
38
A light ray is incident perpendicularly to one face of a $${90^ \circ }$$ prism and is totally internally reflected at the glass-air interface. If the angle of reflection is $${45^ \circ }$$, we conclude that the refractive index $$n$$
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(B)
$$n > \sqrt 2 $$
39
Two spherical conductors $$B$$ and $$C$$ having equal radii and carrying equal charges on them repel each other with a force $$F$$ when kept apart at some distance. A third spherical conductor having same radius as that $$B$$ but uncharged is brought in contact with $$B,$$ then brought in correct with $$C$$ and finally removed away from both. The new force of repulsion between $$B$$ and $$C$$ is
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(D)
$$3$$ $$F/8$$
40
Spherical balls of radius $$R$$ are falling in a viscous fluid of viscosity $$\eta $$ with a velocity $$v.$$ The retarding viscous force acting on the spherical ball is
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(B)
directly proportional to both radius $$R$$ and velocity $$v$$
41
A particle moves in a straight line with retardation proportional to its displacement. Its loss of kinetic energy for any displacement $$x$$ is proportional to
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(C)
$${x^2}$$
42
A uniform chain of length $$2$$ $$m$$ is kept on a table such that a length of $$60$$ $$cm$$ hangs freely from the edge of the table. The total mass of the chain is $$4$$ $$kg.$$ What is the work done in pulling the entire chain on the table?
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(B)
$$3.6$$ $$J$$
43
A force $$\overrightarrow F = \left( {5\overrightarrow i + 3\overrightarrow j + 2\overrightarrow k } \right)N$$ is applied over a particle which displaces it from its origin to the point $$\overrightarrow r = \left( {2\overrightarrow i - \overrightarrow j } \right)m.$$ The work done on the particle in joules is
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(B)
$$+7$$
44
A body of mass $$' m ',$$ acceleration uniformly from rest to $$'{v_1}'$$ in time $${T}$$. The instantaneous power delivered to the body as a function of time is given by
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(B)
$${{mv_1^2t} \over {T^2}}$$
45
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
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(A)
its kinetic energy is constant
46
A machine gun fires a bullet of mass $$40$$ $$g$$ with a velocity $$1200m{s^{ - 1}}.$$ The man holding it can exert a maximum force of $$144$$ $$N$$ on the gun. How many bullets can he fire per second at the most?
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(D)
Three
47
One solid sphere $$A$$ and another hollow sphere $$B$$ are of same mass and same outer radii. Their moment of inertia about their diameters are respectively $${I_A}$$ and $${I_B}$$ such that
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(A)
$${I_A} < {I_B}$$
48
A solid sphere is rotating in free space. If the radius of the sphere is increased keeping mass same which on of the following will not be affected ?
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(B)
Angular momentum
49
A satellite of mass $$m$$ revolves around the earth of radius $$R$$ at a height $$x$$ from its surface. If $$g$$ is the acceleration due to gravity on the surface of the earth, the orbital speed of the satellite is
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(D)
$${\left( {{{g{R^2}} \over {R + x}}} \right)^{1/2}}$$
50
Suppose the gravitational force varies inversely as the n^th power of distance. Then the time period of a planet in circular orbit of radius $$R$$ around the sun will be proportional to
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(C)
$${R^{\left( {{{n + 1} \over 2}} \right)}}$$
51
If $$g$$ is the acceleration due to gravity on the earth's surface, the gain in the potential energy of an object of mass $$m$$ raised from the surface of the earth to a height equal to the radius $$R$$ of the earth is
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(C)
$${1 \over 2}mgR$$
52
The time period of an earth satellite in circular orbit is independent of
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(C)
the mass of the satellite
53
A wire fixed at the upper end stretches by length $$l$$ by applying a force $$F.$$ The work done in stretching is
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(D)
$${{Fl} \over 2}$$
54
If two soap bubbles of different radii are connected by a tube
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(A)
air flows from the smaller bubble to the bigger
55
If the temperature of the sun were to increase from $$T$$ to $$2T$$ and its radius from $$R$$ to $$2R$$, then the ratio of the radiant energy received on earth to what it was previously will be
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(D)
$$64$$
56
One mole of ideal monatomic gas $$\left( {\gamma = 5/3} \right)$$ is mixed with one mole of diatomic gas $$\left( {\gamma = 7/5} \right)$$. What is $$\gamma $$ for the mixture? $$\gamma $$ Denotes the ratio of specific heat at constant pressure, to that at constant volume
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(C)
$$3/2$$
57
Two thermally insulated vessels $$1$$ and $$2$$ are filled with air at temperatures $$\left( {{T_1},{T_2}} \right),$$ volume $$\left( {{V_1},{V_2}} \right)$$ and pressure $$\left( {{P_1},{P_2}} \right)$$ respectively. If the value joining the two vessels is opened, the temperature inside the vessel at equilibrium will be
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(A)
$${T_1}{T_2}\left( {{P_1}{V_1} + {P_2}{V_2}} \right)/\left( {{P_1}{V_1}{T_2} + {P_2}{V_2}{T_1}} \right)$$
58
Which of the following statements is correct for any thermodynamic system ?
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(B)
Internal energy and entropy and state functions
59
The temperature of the two outer surfaces of a composite slab, consisting of two materials having coefficients of thermal conductivity $$K$$ and $$2K$$ and thickness $$x$$ and $$4x,$$ respectively, are $${T_2}$$ and $${T_1}\left( {{T_2} > {T_1}} \right).$$ The rate of heat transfer through the slab, in a steady state is $$\left( {{{A\left( {{T_2} - {T_1}} \right)K} \over x}} \right)f,$$ with $$f$$ equal to
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(D)
$${1 \over 3}$$
60
The bob of a simple pendulum executes simple harmonic motion in water with a period $$t,$$ while the period of oscillation of the bob is $${t_0}$$ in air. Neglecting frictional force of water and given that the density of the bob is $$\left( {4/3} \right) \times 1000\,\,kg/{m^3}.$$ What relationship between $$t$$ and $${t_0}$$ is true
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(A)
$$t = 2{t_0}$$
61
The total energy of particle, executing simple harmonic motion is
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(A)
independent of $$x$$
62
A particle at the end of a spring executes $$S.H.M$$ with a period $${t_1}$$. While the corresponding period for another spring is $${t_2}$$. If the period of oscillation with the two springs in series is $$T$$ then
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(B)
$${T^2} = t_1^2 + t_2^2$$
63
A particle of mass $$m$$ is attached to a spring (of spring constant $$k$$) and has a natural angular frequency $${\omega _0}.$$ An external force $$F(t)$$ proportional to $$\cos \,\omega t\left( {\omega \ne {\omega _0}} \right)$$ is applied to the oscillator. The time displacement of the oscillator will be proportional to
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(B)
$${1 \over {m\left( {\omega _0^2 - {\omega ^2}} \right)}}$$
64
The displacement $$y$$ of a particle in a medium can be expressed as, $$y = {10^{ - 6}}\,\sin $$ $$\left( {100t + 20x + {\pi \over 4}} \right)$$ $$m$$ where $$t$$ is in second and $$x$$ in meter. The speed of the wave is
Одговорити
(B)
$$5\,m/s$$
65
A charge particle $$'q'$$ is shot towards another charged particle $$'Q'$$ which is fixed, with a speed $$'v'$$. It approaches $$'Q'$$ upto a closest distance $$r$$ and then returns. If $$q$$ were given a speed of $$'2v'$$ the closest distances of approaches would be
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(D)
$$r/4$$
66
Two masses $${m_1} = 5kg$$ and $${m_2} = 4.8kg$$ tied to a string are hanging over a light frictionless pulley. What is the acceleration of the masses when left free to move? $$\left( {g = 9.8m/{s^2}} \right)$$
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(C)
$$0.2\,\,m/{s^2}$$
67
Which one of the following represents the correct dimensions of the coefficient of viscosity?
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(A)
ML^-1T^-1
68
A ball is released from the top of a tower of height h meters. It takes T seconds to reach the ground. What is the position of the ball in $${T \over 3}$$ seconds?
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(A)
$${{8h} \over 9}$$ meters from the ground
69
If $$\overrightarrow A \times \overrightarrow B = \overrightarrow B \times \overrightarrow A $$, then the angle beetween A and B is
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(C)
$$\pi $$
70
A projectile can have the same range 'R' for two angles of projection. If T₁ and T₂ be the time of flights in the two cases, then the product of the two time of flights is directly proportional to
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(A)
R
71
Which of the following statements is FALSE for a particle moving in a circle with a constant angular speed?
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(B)
The acceleration vector is tangent to the circle.
72
An automobile travelling with speed of 60 km/h, can brake to stop within a distance of 20 m. If the car is going twice as fast, i.e 120 km/h, the stopping distance will be
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(D)
80 m
73
A ball is thrown from a point with a speed ν₀ at an angle of projection θ. From the same point and at the same instant person starts running with a constant speed $${{{v_0}} \over 2}$$ to catch the ball. Will the person be able to catch the ball? If yes, what should be the angle of projection θ?
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(C)
Yes, $$60^\circ $$
74
A block rests on a rough inclined plane `making an angle of $${30^ \circ }$$ with the horizontal. The coefficient of static friction between the block and the plane is $$0.8.$$ If the frictionless force on the block is $$10$$ $$N,$$ the mass of the block (in $$kg$$) is $$\left( {take\,\,\,g\, = \,10\,\,m/{s^2}} \right)$$
Одговорити
(C)
$$2.0$$