# Electric Charges And Fields Questions

We provide electric charges and fields practice exercises, instructions, and a learning material that allows learners to study outside of the classroom. We focus on electric charges and fields skills mastery so, below you will get all questions that are also asking in the competition exam beside that classroom.

#### List of electric charges and fields Questions

Question NoQuestionsClass
1Which of the following assertions are
correct?
This question has multiple correct options
A. ( A ) neutron can decay to a proton only inside a nucleus.
B. ( A ) proton can change to a neutron only inside a nucleus.
C. An isolated neutron can change into a proton.
D. An isolated proton can change into a neutron.
12
2A large sheet of uniform charge passes
through a hypothetical spherical
surface. The figure shows principle
section of situation. The electric flux
through the spherical surface is given
by
( ^{mathbf{A}} cdot frac{pi R^{2} sigma}{epsilon_{0}} )
B. ( frac{2 pileft(R^{2}-x^{2}right) sigma}{epsilon_{0}} )
( c )
( D )
12
3Four identical pendulums are made by attaching a small ball of mass 100 g on a ( 20 mathrm{cm} ) long thread and suspended from the same point. Now each ball is given charge ( Q ) so that balls move away from each other with each thread
making an angle of ( 45^{circ} ) from the vertical. The value of ( Q ) is close to ( left.frac{1}{4 pi epsilon_{0}}=9 times 10^{9} text { in Sl units }right) )
A . ( 1 mu C )
в. ( 1.5 mu ) С
( c cdot 2 mu c )
D. 2.5 ( mu ) C
12
4A uniform nonconducting rod of mass ( mathrm{m} ) and length ( l, ) with charge density ( lambda ) as shown in figure, is burged at the midpoint at origin so that it can rotate in a horizontal plane without any friction. A uniform electric field E exists
parallel to x-axis in the entire region. Calculate the period of small oscillations of the rod
12
5Two conducting spheres of radii ( r_{1} ) and
( r_{2} ) are equally charged. The ratio of their
potentials is :
A ( cdot r_{1} / r_{2} )
в. ( r_{2} / r_{1} )
( mathbf{c} cdot r_{1}^{2} / r_{2}^{2} )
( mathbf{D} cdot r_{2}^{2} / r_{1}^{2} )
12
6Electrical charge can be transferred from a charged object to another through
A. vacuum
B. air
c. insulator
D. conductor
12
7A cube has sides of length ( L=0.2 mathrm{m} ). It is placed with one corner at the origin as shown in figure.The electric field is uniform and given by ( overrightarrow{boldsymbol{E}}= ) ( (2.5 N / C) dot{I}-(4.2 N / C) j . ) Find the
electric flux through the entire cube.
12
8Consider the charge configuration and
a spherical Gaussian surface as shown
in the figure. When calculating the flux of the electric field over the spherical surface, the electric field will be?
( mathbf{A} cdot ) Due to ( q_{2} )
B. Only due to the positive charges
c. Due to all the charges
D. Due to ( +q_{1} ) and ( -q )
12
9Two point charges ( +q ) and ( +q ) are fixed at ( (a, 0,0) ) and ( (-a, 0,0) . ) A third point charge ( -q ) is at origin. State whether its equilibrium is stable, unstable or neutral if it is slightly displaced along
( boldsymbol{x}- ) axis.
A . Stable
B. Unstable
c. Neutral
D. Data insufficient
12
10There are how many kinds of charges?
A. one
B. Two
c. Three
D. Four
12
11A charge ( Q ) is placed at the corner of a cube. The electric flux through all the faces of the cube is
( mathbf{A} cdot Q / varepsilon_{0} )
в. ( Q / 6 varepsilon_{0} )
c. ( Q / 8 varepsilon_{0} )
D. ( Q / 3 varepsilon_{0} )
12
12Eight dipoles of charges of magnitude ( e )
are placed inside a cube. The total
electric flux coming out of the cube will
be
( A cdot frac{8 e}{varepsilon_{0}} )
В. ( frac{16 e}{varepsilon_{0}} )
( c cdot frac{e}{varepsilon_{0}} )
D. zero
12
13The angle between the dipole moment and electric field at any point on the equatorial plane is :
A ( cdot 0^{circ} )
B. 90
c. ( 180^{circ} )
D. ( 45^{circ} )
12
14A point charge ( +Q ) is placed at point 0 as shown in the figure. Is the potential difference ( V_{A}-V_{B} ) positive, negative
or zero?
12
15Two short dipoles moment P are placed
at two corners of a square as shown in the figure. What is the ratio of magnitudes of electric field at two
points 0 and ( A ? )
( A cdot 2 )
B. ( 2 sqrt{2} )
( c )
D. ( sqrt{2} )
12
16Which of the following is an electrica insulator:
A. Aluminium
B. Gold
c. Rubber
D. None of these
12
17( boldsymbol{epsilon}_{0} ) is known as the
A. electrical permeability of free space
B. electrical permittivity of free space
C. magnetic permeability of free space
D. None of these
12
18A particle of mass ( mathrm{m} ) and charge ( boldsymbol{q} ) is thrown in a region where uniform gravitational field and electric field are present. The path of particle :
This question has multiple correct options
A. may be straight line
B. may be a circle
c. may be a parabola
D. may be a hyperbola
12
19An electric dipole of moment p is kept along an electric field E. The work done
in rotating it from an equilibrium
position by an angle ( boldsymbol{theta} ) is :
( A cdot P E(1-cos theta) )
B. PE(1 – ( sin theta ) )
c. ( P E cos theta )
D. PE sin ( theta )
12
20An electric filament bulb can be worked
from
A. DC supply only
B. AC supply only
c. Battery supply only
D. All above
12
21A moving charge produces.
A. Only electric field
B. Only magnetic field
C. Both electric and magnetic fields
D. Neither the electric field nor the magnetic field
12
22A sure test of electrification is:
A . attraction
B. repulsion
c. friction
D. induction
12
23A particle having a charge of ( 10 mu C ) and
mass ( 1 mu g ) moves in a horizontal circle of radius ( 10 mathrm{cm} ) under the influence of a
magnetic field of 0.1 T. When the particle
is at a point ( P, ) a uniform electric field is
switched on so that the particle starts
moving along the tangent with uniform
velocity. The electric field is
A. ( 0.1 mathrm{V} / mathrm{m} )
B. 1.0 ( mathrm{V} / mathrm{m} )
c. ( 10.0 mathrm{V} / mathrm{m} )
D. ( 100 mathrm{V} / mathrm{m} )
12
24Two coaxial coils are very close to each
other and their mutual inductance is 5
( mathrm{mH} ). If a current ( 50 sin 500 r ) is passed in
one of the coils then the peak value of induced e.m.f. in the secondary coil will
be?
A . ( 5000 v )
в. ( 500 v )
( c .150 v )
D. 125v
12
25Electric intensity due to a charged sphere at a point outside the sphere decreases with
A. increase in charge on sphere
B. increase in dielectric constant
c. decrease in the distance from the centre of sphere
D. decrease in square of distance from the centre of sphere
12
26Which of the following statements are
true:
A: Charge cannot exist without mass but mass can exist without charge
B: Charge is invariant but mass varies
with velocity
C: Charge is conserved but mass alone
may not be conserved
( A cdot A, B, C ) are true
B. A, B, C are not true
c. ( A, B ) are only true
D. ( A, B ) are false, ( C ) is true
12
27If the magnitude of intensity of electric
field at a distance ( x ) on axial line and at
a distance ( y ) on equational line on a given dipole are equal, then ( x: y ) is ?
12
28An electric dipole is held in a uniform
electric field.
(i) Show that the net force acting on it is
zero
(ii) The dipole is aligned parallel to the field. Find the work in rotating it through the angle of ( 180^{circ} )
12
29Which of the following is not a unit of charge?
A. coulomb
B. ampere-second
c. microcoulomb
D. ampere/second
12
30An infinite number of charges each
equal to ( q ) are placed along the ( x ) -axis at ( boldsymbol{x}=mathbf{1}, boldsymbol{x}=mathbf{2}, boldsymbol{x}=mathbf{4}, boldsymbol{x}=mathbf{8} ) and ( mathbf{s} mathbf{o} ) on
Find the potential and electric field at the point ( x=0 ) due to this set of
charges.
A ( cdot_{5 k q}, frac{4 k g}{3} )
в. ( 2 k q, frac{4 k g}{3} )
c. ( _{3 k q}, frac{4 k g}{3} )
D. ( 7 k q, frac{4 k g}{4} )
12
31The bob of a pendulum is positively charged. Another identical charge is placed at the point of suspension of the pendulum. The time period of pendulum
A. increases
B. decreases
c. becomes zero
D. remains same
12
32Rub a piece of ebonite across a piece of
animal fur. What happens?
A. the fur has a slightly positive charge and the ebonite is slightly negative
B. the fur has a slightly positive charge and the ebonite is also slightly positive
C. the fur has a slightly negative charge and the ebonite is also slightly negative
D. the fur has a slightly negative charge and the ebonite is slightly positive
12
33Consider two concentric spherical
metal shells of radii ‘a’ and b> a. The
outer shell has charge ( Q, ) but the inner shell has no charge,Now,the inner shell is grounded. This means that the inner
shell will come at zero potential and that electric fields lines leave the outer
hell and end on the inner shell.
12
34State the effect on the divergence of the leaves of a gold leaf electroscope on bringing a negatively charged rod near it if the electroscope is negatively
charged:
A. Divergence decreases
B. Divergence increases
c. Divergence remains same
D. can’t say
12
35An electron is projected from a distance
( d ) and with initial velocity ( u ) parallel to a uniformly charged flat conducting plate
as shown. It strikes the plate after
travelling a distance ( ell ) along the direction of projection. The surface
charge density of the conducting plate is equal to
A ( cdot frac{2 d varepsilon_{0} m u^{2}}{e ell^{2}} )
B. ( frac{2 d varepsilon_{0} m u}{e ell^{2}} )
c. ( frac{d varepsilon_{0} m u^{2}}{e ell} )
D. ( frac{d varepsilon_{0} m u}{e l} )
12
36How will you determine the electric field
a any point along the axial line of an electric dipole.
12
37(a) Which physical quantity has its ( mathrm{S} ) I unit ( (1) mathrm{Cm}(2) mathrm{N} / mathrm{C} )
(b) Two point charges ( q ) and ( -q ) is placed at a distance ( 2 a ) apart. Calculate the
electric field at a point ( P ) is situated at a distance r along the perpendicular bisector of the line joining the charges. What is the electric field when ( r>> ) a?
Also, give the direction of electric field
w.r.t. electric dipole moment?
12
38The electric potential ( V ) at any point
( (x, y, z) ) in space is given by ( V=3 x^{2} )
where ( x, y, z ) are all in metre. The
electric field at the point ( (1 m, 0,2 m) ) is
A ( cdot 6 V m^{-1} ) along negative ( x ) -axis
B. ( 6 V m^{-1} ) along positive ( x ) -axis
C. ( 12 mathrm{Vm}^{-1} ) along negative ( x ) -axis
D. ( 12 mathrm{Vm}^{-1} ) along positive ( x ) -axis
E. ( 8 mathrm{Vm}^{-1} ) along negative ( x ) -axis
12
39Two point charges ( +3 mu C ) and ( +8 mu C ) repel each other with a force of ( 40 N . ) If a
charge of ( -5 mu C ) is added to each of them, the force between them will become:
A ( .-10 N )
B. ( 10 N )
( c .20 N )
D. ( -20 N )
12
40The law that describes the force as
directly proportional to magnitude of charges and inversely proportional to the distance between the charges is
known as:
A. Newton’s law
B. Coulomb’s law
c. Gauss’s law
D. Ohm’s law
12
41If the electric field at points In between,
and is ( K sigma / varepsilon_{0} . ) Find ( mathrm{K} ? )
12
42Ordinary rubber is an insulator. But the
special rubber tyres of aircrafts are made slightly conducting. Why is this
necessary?
12
43An electric dipole of diploe moment ( overrightarrow{boldsymbol{p}} ) placed in uniform electric field ( overrightarrow{boldsymbol{E}} ) has
minimum potential energy when angle between ( vec{p} ) and ( overrightarrow{boldsymbol{E}} )
( ^{A} cdot frac{pi}{2} )
B. zero
c. ( pi )
D. ( frac{3 pi}{2} )
12
44A body is brought near to a negatively charged gold leaf electroscope. If the divergence of leaves increases. What is the nature of charge on the body?
A. Positive
B. Negative
c. No charge
D. cant say
12
45From the schematic electric field lines,
we can infer that
A. the left charge is higher in magnitude than the right
one
B. the left charge is lower in magnitude than the right one
c. the left charge is equal in magnitude to the right one
D. None of these
12
46A ball of radius R carries a positive charge whose volume charge density depends only on the distance r from the ball’s centre as: ( rho=rho_{0}left(1-frac{r}{R}right) ) where
( rho_{0} ) is constant. Assume ( epsilon ) as the
permittivity of the ball.
Then the magnitude of the electric field as a function of the distance r outside
the ball is given by :
A. ( quad E=frac{rho_{0} R^{3}}{8 epsilon r^{2}} )
в. ( quad E=frac{rho_{0} R^{3}}{12 r r^{2}} )
c. ( _{E=frac{rho_{0} R^{3}}{16 epsilon^{2}}} )
D. ( quad E=frac{rho_{0} R^{3}}{24 r^{2}} )
12
47What is the net charge on an neutral
atom?
A. positive
B. negative
c. zero
D. none of these
12
48A negative charged object reples another charged object kept close to it. What is the nature of the charge on the other object?
A. positive
B. negative
c. both
D. none
12
49A charged glass rod will get discharged
on
A. connecting it to the earth
B. connecting it to another glass rod
c. breaking the ends of the rod
D. Any of the above
12
50Determine the electric field everywhere
outside the sphere at a distance ( r(>> )
( boldsymbol{a}) ) from the centre
A ( cdot E=frac{Q}{4 pi epsilon_{0} r^{2}} )
B. ( quad E=frac{Q}{4 pi epsilon_{0} r} )
c. ( quad E=frac{Q}{4 pi epsilon_{0} a^{2}} )
D. ( quad E=frac{Q}{4 pi epsilon_{0} a} )
12
51An electric dipole of momentum ( vec{p} ) is placed in a uniform electric field. The dipole is rotated through a very smal angle from equilibrium and is released. Prove that it executes simple harmonic motion with frequency ( f=frac{1}{2 pi} sqrt{frac{p E}{1}} )
Where, ( I= ) moment of inertia of the
dipole.
12
52Three long wires with same current placed at three corners of an equilateral triangles as shown in figure then the magnetic field at the centre of the
triangle will be (side length of
triangle is a)
12
53A pith ball of mass ( 9 times 10^{-5} k g ) carries a
charge of ( 5 mu C ). What must be charge on
another pith ball placed directly ( 2 mathrm{cm} ) above the pith ball such that they are held in equilibrium?
A . ( 3.2 times 10^{-11} C )
B . ( 7.84 times 10^{-12} C )
c. ( 1.2 times 10^{-13} C )
D. ( 1.6 times 10^{-19} C )
12
54As one penetrates through uniformly charged conducting sphere, what happens to the electric field strength:
A. decreases inversely as the square of the distance
B. decreases inversely as the distance
c. becomes zero
D. increases inversely as the square of distance
12
55Three points charges are placed at the
corners of an equilateral triangle of side
( L ) shown in the figure.
This question has multiple correct options
A. The potential at the centroid of the triangle is zero
B. The electric field at the centroid of the triangle is zero
C. The dipole moment of the system is ( sqrt{2} q L )
D. The dipole moment of the system is ( sqrt{3} q L )
12
56There are two charges ( +2 mu C ) and ( – )
( 3 mu C . ) The ratio of forces acting on them
will be
A .2: 3
B. 1: 1
c. 3: 2
D. 4: 9
12
57Two free positive charges ( 4 q ) and ( q ) are
at a distance ( l ) apart. What charge ( Q ) is needed to achieve equilibrium for the entire system and where should it be
placed from charge ( q ? )
( left.^{mathbf{A}} cdot Q=frac{4}{9} q quad text { (negative at } frac{l}{3}right) )
( left.^{mathrm{B}} Q=frac{4}{9} q quad text { (positive at } frac{l}{3}right) )
( left.^{mathrm{c}} Q=q quad text { (positive at } frac{l}{3}right) )
( left.^{mathrm{D}} Q=q quad text { (negative at } frac{l}{3}right) )
12
58Fig. shows a point charge of ( 0.5 times 10^{-6} )
( mathrm{C} ) at the center of the spherical cavity of
radius ( 3 c m ) of a piece of metal. The
electric field at :
This question has multiple correct options
A. A (2cm from the charge) is 0
B. A (2 cm from the charge) is ( 1.125 times 10^{7} mathrm{NC}^{-1} )
C. B ( ( 5 mathrm{cm} ) from the charge ) is 0
D. B (5cm from the charge) is ( 1.8 times 10^{6} mathrm{NC}^{-1} )
12
59Which of the following is/are bad conductors of heat?

This question has multiple correct options
A. Glass
B. Aluminium
c. Iron
D. woodd

12
60( A ) and ( B ) are two identical spherical
charged bodies which repel each other with force ( F, ) kept at a finite distance apart A third uncharged sphere of the same size is brought in contact with sphere ( mathrm{B} ) and removed. It is then kept at mid-point of ( A ) and ( B ) find the magnitude of force on ( mathbf{C} )
( A cdot F / 2 )
B. F/8
( c cdot F )
D. zero
12
61A region in space has a total charge ( Q )
distributed spherically such that the
volume charge density ( rho(r) ) is given by
( boldsymbol{rho}(boldsymbol{r})=boldsymbol{3} boldsymbol{a} boldsymbol{r}(boldsymbol{2} boldsymbol{R}) )
for ( r leq frac{R}{2} )
( boldsymbol{rho}(boldsymbol{r})=boldsymbol{a}left[mathbf{1}-left(frac{r}{R}right)^{2}right] quad ) for ( frac{R}{2} leq r leq )
( boldsymbol{R} )
( rho(r)=0 )
for ( r>R )
Find the electric field at ( rholeft(frac{R}{2}<x<Rright) )
12
62Three small spheres, each carrying a
charge ( q ) are placed on the circumference of a circle of radius ( R )
forming an equilateral triangle. If we
place another charge ( Q ) at the center of the circle, then the force on ( Q ) will be
A. zero
В. ( frac{1}{4 pi epsilon_{0}} times frac{q Q}{R^{2}} )
c. ( frac{1}{4 pi epsilon_{0}} times frac{2 q Q}{R^{2}} )
D. ( frac{1}{4 pi epsilon_{0}} times frac{3 q Q}{R^{2}} )
12
63The total flux passing through the cube
is
A ( .-0.135 N m^{2} C^{-1} )
B . ( -0.054 N m^{2} C^{-1} )
¿. ( 0.081 N m^{2} C^{-} )
D. zer
12
64012
65The net charge inside an isolated system is
A. conserved
B. variable
c. zero
D. infinite.
12
668
asic
placed at a point ( O . ) The arrows show
the direction of the magnetic moment.
The other arrows show different
positions (and orientations of the
magnetic moment) of another identical
magnetised needle ( Q ). The dotted line
represent a circle centre at the
midpoint of ( boldsymbol{P} )
Which configuration in this system
corresponds to stable equilibrium?
( mathbf{A} cdot P Q_{1}, P Q_{3} )
B. ( P Q_{3}, P Q_{5} )
( mathbf{c} cdot P Q_{2}, P Q_{4} )
D. ( P Q_{2}, P Q_{3} )
12
67Five point charges, each of value ( +q ) are placed on five vertices of a regular hexagon of side L. What is the magnitude of the force on a point charge of value -q placed at the centre of the hexagon?12
68If a soap bubble, having radius ( r, ) is
charged to a charge density ( sigma ) and its
increased to ( R ), then ( R ) equals to
( [T ) is the surface tension]
A ( cdot R=frac{9 varepsilon_{0} T}{sigma^{2}} )
в. ( quad R=frac{8 varepsilon_{0} T}{sigma^{2}} )
c. ( R=frac{10 varepsilon_{0} T}{sigma^{2}} )
D. ( R=frac{11 varepsilon_{0} T}{sigma^{2}} )
12
69A point charge ( q ) is palced on vertex of right circular cone. the semi-vertical
angle of cone
A. ( frac{q}{epsilon_{0}} )
в. ( frac{q}{2 epsilon_{0}} )
c. ( frac{q}{3 epsilon_{0}} )
D. ( frac{q}{4 epsilon_{0}} )
12
70A solid non conducting sphere charged
in such a way that in it as we move away from the centre, the electric field
decreases then which of the following statement is correct :
A. the sphere in uniformly charged
B. the potential at surface is less than that at its centre
c. the potential at surface is more than that at its centre
D. the potential at surface may be less than that at its centre
12
71Two plastic drinking straws are vigorously rubbed with a piece of wool
Then they are brought near each other as shown above. What observation con
you make?
A. They attract eachother
B. They repel eachother
c. nothing will happen
D. can’t say
12
72If one penetrates a uniformly charged spherical cloud, electric field strength
A. Decreases directly as the distance from the centre
B. Increases directly as the distance from the centre
c. Remains constant
D. None of the above
12
73A gold leaf electroscope is given a positive charge so that its leaves diverge. How is the divergence of leaves affected, when a glass rod rubbed with
silk is rolled on the disc of
electroscope?
A. divergence increases
B. divergence decreases
c. divergence remains same
D. can’t say
12
74When a glass rod is rubbed with silk,
the charge acquired by the silk is :
A. negative
B. positive
c. partly positive and partly negative
D. none of these
12
75The electric potential due to a dipole at a point on the perpendicular bisector of its length is :
A. maximum
B. minimum
c. 0
D. None of these
12
76A dipole is placed in a shell as shown
Find the electric flux emerging out of
the shell and in a hypothetical sphere of
A. ( frac{2 q}{8} )
В ( cdot frac{q}{varepsilon_{0}}, frac{-q}{varepsilon_{0}} )
c. ( frac{-q}{varepsilon_{0}}, frac{q}{varepsilon_{0}} )
0.0
12
77It is required to hold equal charges, ( boldsymbol{q} ) in
equilibrium at the corners of a square. What charge when placed at the centre
of the square will do this?
12
78The gold leaves of a gold-leaf electroscope are enclosed in a glass
bottle
A. to protect the gold leaves from drafts of air.
B. to protect the gold leaves from rusting.
c. To protect the gold leaves from wear and tear.
D. All of the above
12
79Four point charges ( Q, q, Q ) and ( q ) are
placed at the corners of a square of side
( a^{prime} ) as shown in the figure.
Find the
(a) resultant electric force on a charge
( Q, ) and
(b) potential energy of this system.
12
80Assertion
Electron revolves around a positively charged nucleus like a planet revolves around the sun.
Reason
The force acting in both the cases is of
same kind.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
81Three concentric spherical metallic shells ( A, B ) and ( C ) of radii ( a, b ) and ( c(c>b )
a) have charge densities ( sigma,-sigma ) and ( sigma ) respectively.The potential of shell B is :
A ( cdot(a+b+c) frac{sigma}{varepsilon_{0}} )
B ( cdotleft(frac{a^{2}}{b}-b+cright) frac{sigma}{varepsilon_{0}} )
( ^{mathbf{c}} cdotleft(frac{a^{2}}{c}-frac{b^{2}}{c}+cright) frac{sigma}{varepsilon_{0}} )
D. ( frac{sigma c}{varepsilon_{0}} )
12
82density ( +sigma ) and ( -sigma ) are parallel to each other as show in figure. Electric field at
the
This question has multiple correct options
A. points to the left or to the right of the sheets is zero.
B. midpoint between the sheets is zero.
C. midpoint of the sheets is ( sigma / varepsilon_{0} ) and is directed towards right
D. midpoint of the sheets is ( 2 sigma / varepsilon_{0} ) and is directed towards right
12
83In the figure shown below the
conducting shell ( A ) having radius ( R ) is
given charge ( Q ) initially. The shell ( A ) is connected to shell ( B ) of radius ( 2 R ) via
switch ( S ) and a conducting wire. The
switch ( S ) is closed at ( t=0, ) then charge density on the shell ( B ) is (Assuming separation between ( boldsymbol{A} ) and
( B ) is very very large)
( A )
в. ( frac{Q}{24 pi R^{2}} )
c. ( frac{Q}{12 pi R^{2}} )
D. ( frac{Q}{6 pi R^{2}} )
12
84When a piece of polythene is rubbed with wool, a charge of ( -2 times 10^{-7} C ) is
developed on polythene. What mass is transferred to polythene?
( mathbf{A} cdot 5.69 times 10^{-19} k g )
B . ( 2.25 times 10^{-19} k g )
( mathbf{c} cdot 9.63 times 10^{-19} k g )
D. ( 11.38 times 10^{-19} mathrm{kg} )
12
85In identical mercury droplets charged to the same potential ( V ) coalesce to form a single bigger drop. The potential of the new drop will be:
A ( cdot frac{V}{n} )
в. ( n V )
c. ( N V^{2} )
D. ( frac{2}{n^{3} V} )
12
86Three identical small balls, each of
mass ( 0.1 mathrm{g}, ) are suspended at one point on silk thread having a length of ( 1= ) 20cm. What charges should be imparted to the balls for each thread to
form an angle of ( alpha=30^{circ} ) with the
vertical?
12
87A charge ( Q ) is placed at a distance ( a / 2 )
above the centre of the square surface
of edge a as shown in the figure. The
electric flux through the square surface
is :
A ( cdot frac{Q}{3 epsilon_{0}} )
в. ( frac{Q}{6 epsilon_{0}} )
c. ( frac{Q}{2 epsilon_{0}} )
D. ( frac{Q}{epsilon_{0}} )
12
88Electric potential on the surface of a
hollow conducting sphere is V. The electric potential is ( frac{V}{2} ) at a distance
A ( cdot frac{R}{2} ) inside the sphere
B. ( frac{R}{2} ) from the surface of the sphere and outside it
C. ( 2 mathrm{R} ) from the centre of the sphere
D. ( 2 mathrm{R} ) from the surface of the sphere and outside it
12
89A charge ( Q ) is distributed over two concentric hollow spheres of radii ( r ) and
( R(R>r) ) such that their surface
densities are equal. The charge on smaller and bigger shells are:
A. ( frac{Q r^{2}}{r^{2}+R^{2}} ) and ( frac{Q R^{2}}{r^{2}+R^{2}}, ) respectively
в. ( Qleft(1+frac{r^{2}}{R^{2}}right) ) and ( Qleft(1+frac{R^{2}}{r^{2}}right) ), respectivel
( ^{mathrm{c}} Qleft(1-frac{r^{2}}{R^{2}}right) ) and ( Qleft(1-frac{R^{2}}{r^{2}}right) ), respectivel
D. ( frac{Q R^{2}}{r^{2}+R^{2}} ) and ( frac{Q r^{2}}{r^{2}+R^{2}}, ) respectively
12
90A point charge ( 50 mu C ) is located in the
( x-y ) plane at the position vector ( vec{r}_{0}= ) ( (2 hat{i}+3 hat{j}) m . ) The electric field at the
point of position vector ( vec{r}= ) ( (8 hat{i}-5 hat{j}) m, ) in vector from is equal to:
A ( cdot 900(-3 hat{i}+4 hat{j}) V / m )
B ( cdot 90(3 hat{i}-4 hat{j}) V / m )
c. ( 9(-3 hat{i}+4 hat{j}) V / m )
D. ( 900(3 hat{i}-4 hat{j}) V / m )
12
91Which among the following is an example of polar molecule?
( A cdot O_{2} )
в. ( H_{2} )
c. ( N_{2} )
D. нс
12
92There is an electric field ( boldsymbol{E} ) in ( boldsymbol{X} )
=direction. If work done in moving a
charge ( 0.2 C ) through a distance of ( 2 m )
along a line making an angle of 60 degree with ( X ) -axis is 4.0 joule, what
is the value of ( boldsymbol{E} ) ?
A. ( sqrt{3} ) newton per coulomb
B. 4 newton per coulomb
c. 5 newton per coulomb
D. None of these
12
93Lightning is a phenomenon
A. Electromagnetic
B. Current electricity
c. Electrochemical
D. Electrostatic
12
(i) An electrostatic field line is a
continuous curve. That is, a field line
cannot have sudden breaks. Why is it
so?
(ii) Explain why two field lines never
cross each other at any point.
12
95A charged particle is in the electric field experiences a electric force. All particles which are given below are kept in the electric field of same strength. Which of the following particles would experience the greatest electric force?
A. proton
B. electron
c. alpha particle
D. neutron
E. photon
12
96A charged body is brought near a positively charged gold leaf electroscope. The divergence of its leaves increases. If the same body is brought near a negatively charged gold leaf electroscope, what will be the effect
on divergence of its leaves?
12
97Two point charge ( Q ) and ( -3 Q ) are placed at some distance apart. If the electric field at the location of ( Q ) is ( vec{E} ), the field at the location of ( -3 Q ) is:
A. ( vec{E} )
в. ( -vec{E} )
c. ( +frac{vec{E}}{3} )
D. ( -frac{vec{E}}{3} )
12
98A charged particle is released from rest in a region of steady and uniform electric and magnetic field which are parallel to each other. The nature of light
A . circle
B. Parabola
c. Straight line
D. Helix
12
99An electric dipole of moment ( overrightarrow{boldsymbol{p}} ) is placed at the origin along the ( x ) -axis. The angle made by electric field with ( x ) axis at a point ( P, ) whose position vector makes an angle ( theta ) with ( x ) -axis, is (where ( left.tan alpha=frac{1}{2} tan thetaright) )
( A cdot alpha )
B. ( theta )
( c cdot theta+alpha )
D. ( theta+2 alpha )
12
100Two identical charges of magnitude ( +mathrm{Q} ) are fixed as shown.A third charge – ( Q )
is placed mid way between them at point P. Then small displacements of – Q are made in the directions indicated by
arrows. The -Q is stable with respect to displacement .
( odot ) (out of the What is and
A . I and III
B. I and
c. ॥ and ( I V )
D. III and ( v )
E. stable for any small displacement
12
101Three equal charges, each having a
magnitude of ( 2.0 times 10^{-6} C ) are placed
at the three corners of a right angled triangle of sides ( 3 mathrm{cm}, 4 mathrm{cm} ) and ( 5 mathrm{cm} ) The force (in magnitude) on the charge
at the right angled corner is :
( A .50 N )
B . ( 26 N )
( mathbf{c} cdot 29 N )
D. 45.9 N
12
102If positively charged pendulum is oscillating in a uniform electric field as shown in figure. Its time period as compared to that when it was
uncharged:
A. will increase
B. will decreas
c. will not change
D. will first increase then decreas
12
103An infinite number of charges, each of
charge ( 1 mu C ) are placed on the ( x ) -axis with co-ordinates ( x=1,2,4,8, dots dots dots ) an charge of ( 1 mathrm{C} ) is kept at the origin, then what is the net force acting on ( 1 mathrm{C} ) charge
A. 9000 N
B. 12000 N
c. ( 24000 mathrm{N} )
D. 36000 N
12
104An electric dipole is placed near a positive charge. It will experience:
A. a torque only
B. a force only
c. both torque and force
D. it will depend on the orientation of the dipole with respect to the charge
12
105If a glass rod is rubbed on silk cloth and
then brought near the bits of paper it…..
then
A. Attracts
B. Repel
c. Both
D. None
12
106If the intensity of electric field at a distance ( x ) from the centre in axial
position of small electric dipole is equal
to the intensity at a distance ( y ) in
equatorial position, then
( mathbf{A} cdot x=y )
в. ( x=y / 2 )
C ( . y=x / 2^{2 / 3} )
D. ( y=x / 2^{1 / 3} )
12
107A particle having charge ( q ) and mass ( m ) is projected with velocity ( overrightarrow{boldsymbol{v}}=2 hat{mathbf{i}}-mathbf{3} hat{mathbf{j}} )
in a uniform electric field ( overrightarrow{boldsymbol{E}}=boldsymbol{E}_{0} cdot hat{boldsymbol{j}} )
Change in momentum ( |Delta bar{p}| ) during any
time interval ( t ) is given by:
A ( cdot sqrt{q E_{0} t} )
в. ( q E_{0} )
c. ( frac{q E_{0} t}{m} )
D. zero
12
108Electric force ( quad ) on the nature of
the medium between the charges.
A. depends
B. does not depend
c. sometimes depends
D. None of these
12
109Three positive charge each of magnitude ( Q ) are placed at the corner of the equilateral tringle. The value of charges placed at the centroid of the triangle such that system must be in equilibrium is
( ^{A} cdot frac{+Q}{sqrt{3}} )
в. ( frac{-Q}{sqrt{3}} )
c. ( frac{-2 Q}{sqrt{3}} )
D. ( frac{+2 Q}{sqrt{3}} )
12
110Explain the principle of a device that can build up high voltage of the order of few million volts

Draw a schematic diagram and explain the working of this device Is there any restriction on the upper
limit of high voltage set up in this machine? Explain.
OR
(a) Define electric flux. Write its S.
units
(b) Using Gauss’s law, prove that the electric field at a point due to a uniformly charge infinite plane sheet is independent of the distance from it
(c) How is the field directed if (i) the
sheet is positively charged,(ii) negatively charged?

12
111Figure shows a closed surface which intersects a conducting sphere. If a positive charge is placed at point ( P ), find the sign of flux passing through the curved surface S.12
112In case of conductors and insulators, if an electric field is applied then conduction current density ( (vec{J}) ) is:
This question has multiple correct options
A. in the direction of electron flow
B. in the direction of proton flow.
c. in the direction of electric field
D. against the direction of electric field
12
113Differentiate between conductors and
insulators (any two points).
12
114The electric field in the region ( r<a ) is
( boldsymbol{E}=frac{boldsymbol{Y} boldsymbol{Q} boldsymbol{r}}{boldsymbol{a}^{3}} . ) Find ( boldsymbol{Y} ? )
12
115Gaussian surface obtains a measure
of the electric charge within the surface
A. depending how that internal charge is configured.
B. no matter how that internal charge is configured.
C. and may sometimes depend how that internal charge is configured
D. None of these
12
116The potential at a distance R/2 from the centre of a conducting sphere will be:-
A. 0
В. ( frac{Q}{8 pi epsilon_{E} R} )
c. ( frac{Q}{4 pi epsilon_{c} R} )
D. none of these
12
117Coulomb of charge contains
( overline{mathbf{2 5}} )
electrons
( mathbf{A} cdot 10^{15} )
В. ( 10^{18} )
( c cdot 10^{20} )
D. None of these
12
118If we rotate the dipole of moment ( p )
placed in an electric field ( boldsymbol{E} ) from an ( boldsymbol{theta}_{mathbf{1}} )
to ( theta_{2} ), the work done by the external force is
A ( cdot p Eleft(cos theta_{2}-cos theta_{1}right) )
B . ( p Eleft(cos theta_{1}-cos theta_{2}right) )
c. ( p Eleft(sin theta_{2}-sin theta_{1}right) )
D・ ( p Eleft(sin theta_{1}-sin theta_{2}right) )
12
119Which of the following is not a property of electric lines of force?
A. Lines of force start from positive charge and terminate at negative charge
B. Lines of force always intersect
c. The tangent to a line of force at any point gives the direction of the electric field(E) at that point
D. The number of lines per unit area, through a plane at right angles to the lines, is proportional to the magnitude of elctric field(E)
12
120In the basic ( C s C l ) crystal structure,
( C s^{+} ) and ( C l^{-} ) ions are arranged in a bcc
configuration as shown in the figure. The net electrostatic force exerted by
the eight ( C s^{+} ) ions on the ( C l^{-} ) ion is :
( ^{A} cdot frac{1}{4 pi varepsilon_{0}} frac{4 e^{2}}{3 a^{2}} )
B. ( frac{1}{4 pi varepsilon_{0}} frac{16 e^{2}}{3 a^{2}} )
c. ( 1 frac{32 e^{2}}{3 a^{2}} )
( D )
12
121Assertion
Heart can be assumed as electric
dipole.
Reason
Its ELOF are just same like a normal
dipole.
A. Both Assertion and Reason are correct and Reason is
the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
122Consider a uniformly charged sphere that has a total charge of ( Q ) that has a
radius of ( R ). What is the electrostatic
potential difference, ( Delta V ), between the
centre of the sphere and the surface of
the sphere?
A ( cdot frac{4 k_{e} q}{R} )
в. ( frac{2 k_{e} q}{R} )
c. ( frac{k_{e} q}{R} )
D. ( frac{k_{e q}}{2 R_{q}} )
12
123Positive and negative point charges of equal magnitude are kept at ( left(0,0, frac{a}{2}right) ) and ( left(0,0, frac{-a}{2}right) )
respectively. The work done by the electric field when another positive
point charge is moved from ( (-a, 0,0) ) to ( (0, a, 0) ) is
A. Positive
B. Negative
c. zero
D. Depends on the path connecting the initial and final positions
12
124In a charged spherical conductor id radius ( 10 mathrm{cm} ) has potential ( V ) at point
distant ( 5 c m ) from its center, then the
potential at a point ( 15 mathrm{cm} ) away from the
center will be then
A. ( 3 V )
в. ( frac{3}{2} V )
c. ( frac{2}{3} V )
D. ( frac{1}{3} v )
12
125Find the magnitude of charge appearing on each piece12
126Electric field lines are shown in Fig.
State whether the electric potential
is greater at A or B.
12
127A molecule has a permanent electric dipole moment of ( 5 times 10^{-30} C-m ). If it
is supposed to arise from net charge of
( +e ) and ( -e ) in the two regions of the
molecule, what is their separation?
12
128A system consists of a uniformly charged sphere of radius ( boldsymbol{R} ) and ( mathbf{a} ) surrounding medium filled by a charge
with the volume density ( rho=frac{alpha}{r}, ) where
( alpha ) is a positive constant and ( r ) is the
distance from the centre of the sphere.
Find the charge of the sphere for which the electric field intensity ( boldsymbol{E} ) outside the
sphere is independent of ( boldsymbol{R} )
( ^{mathrm{A}} cdot frac{alpha}{2 varepsilon_{0}} )
в. ( frac{2}{alpha varepsilon_{0}} )
( c cdot 2 pi alpha R^{2} )
D. None of these
12
129Assertion
Gaussian surface is considered
carefully.
Reason
The point where electric field to be
calculated should be within the surface.
A. Both Assertion and Reason are correct and Reason is
the correct explanation for Assertion.
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
C. Assertion is correct but Reason is incorrect.
D. Both Assertion and Reason are incorrect.
12
130If a charge ( -150 n C ) is given to a concentric spherical shell and a charge ( +50 n C ) is placed at its centre, then the
charge on inner and outer surface of the shell is
A. ( 50 n C, 100 n C )
в. ( -50 n C,-100 n C )
c. ( 50 n C, 200 n C )
D. ( -50 n C,-200 n C )
12
131Out of two copper spheres of the same
size, ( x ) is hollow while ( y ) is solid. If they
are charged at the same potential, what can be said about the charges on them?
A. Charge on both the spheres is zero
B. Charge on both the spheres is equal
c. sphere ( y ) will have more charge
D. sphere ( x ) will have more charge
12
132Calculate the electric potential at point
( R ) on the ( x- ) axis
A . 0
B. ( V=frac{q}{4 pi epsilon_{o} sqrt{a^{2}+y^{2}}} )
c. ( V=frac{q}{4 pi epsilon_{o}}left(frac{1}{x+a}-frac{1}{x-a}right) )
( V=frac{q}{4 pi epsilon_{o}}left(frac{1}{x+a}+frac{1}{x-a}right) )
12
133Coulomb’s law for electrostatic force
between two point charges and Newton’s law for gravitational force
between two stationary point masses, both have inverse-square dependence on the distance between the
charges/masses.
(a) Compare the strength of these forces by determining the ratio of their magnitudes (i) for an electron and a proton and (ii) for two protons.
(b) Estimate the accelerations of electron and proton due to the
electrical force of their mutual
attraction when they are ( 1 A )
( left.mathbf{1 0}^{-mathbf{1 0}} boldsymbol{m}right) ) apart? ( left(boldsymbol{m}_{boldsymbol{p}}=mathbf{1 . 6 7} timesright. )
( left.mathbf{1 0}^{-mathbf{2 7}} mathbf{k g}, boldsymbol{m}_{e}=mathbf{9 . 1 1} times mathbf{1 0}^{-mathbf{3 1}} mathbf{k g}right) )
12
134A body has a charge of one coulomb. The
number of excess (or lesser) electrons
on it from its normal state will be :
( A cdot infty )
B . ( 1.6 times 10^{-19} )
( mathbf{c} cdot 1.6 times 10^{19} )
D. ( 6.25 times 10^{18} )
12
135Charge 1 attracts Charge ( 2, ) Charge 2 repels Charge ( 3, ) and Charge 3 attracts Charge 4. Which of the following option must hold good for the given condition of four point charges?
A. Charge 1 attracts Charge 4
B. Charge 2 attracts Charge 3
c. charge 1 repels Charge 3
D. charge 2 repels Charge 4
E. charge 1 repels charge 4
12
136A flat square sheet of charge (side 50 ( mathrm{cm} ) carries a uniform surface charge density. An electron 0.5 cm from a point near the center of the sheet experiences a force of ( 1.8 times 10^{-12} N ) directed away
from the sheet. Determine the total
charge on the sheet
12
137Find the electric field in the region
labelled 3
( A cdot 0 )
B ( cdot k_{e} frac{q}{r^{2}} )
( c cdot 2 k_{e} frac{q}{r^{2}} )
( mathrm{D} cdot 3 k_{e} frac{q}{r^{2}} )
12
138Electric field produced due to an infinitely long straight uniformly charged wire at perpendicular distance of ( 2 c m ) is ( 3 times 10^{8} N C^{-1} ). Then, linear
charge density on the wire is
( left(K=9 times 10^{9} S I quad text { unit }right) )
A ( cdot 3.33 frac{mu C}{m} )
в. ( 333 frac{mu C}{m} )
c. ( quad 666 frac{mu C}{m} )
D. ( 6.66 frac{mu C}{m} )
12
139The magnetic flux through a coil perpendicular to the plane is varying according to the relation ( varphi= )
( left(5 t^{3}+4 t^{2}+2 t-5right) ) wb. Calculate the
induced current through the coil at ( t= )
2 sec, if the resistance of the coil is ( 5 Omega )
12
140A point charge q of mass ( mathrm{m} ) is located at the center of a ring having radius ( mathrm{R} ) and charge Q.When it is displaced slightly, the point charge accelerates along the x-axis to infinity, the ultimate speed of
the point charge:-
A ( cdot sqrt{frac{2 K Q q}{m R}} )
в. ( sqrt{frac{K Q q}{m R}} )
c. ( sqrt{frac{K Q q}{2 m R}} )
D. zero
12
141Charging by friction is used to develop charges on
A. metals
B. conductors
c. insulators
D. Non of these
12
142Udxidı Canıt ILyplicaliy ustu IUI CdNIE
and satellite tv) has its signal run on a
copper wire surrounded by an insulator which is surrounded by the ground wire,
as opposed to the typical side by side
configuration.
What is the most logical reason for
this?
A. The energy held in the electric field between the inside wire and the outside allow for a clearer signal.
B. The outside wire prevents any magnetic field from the inside wire from leaking out of the wire
C. The outside wire prevents electric fields from interfering with the signal in the inside wire
D. The overall resistance of the wire is reduced using this configuration.
12
143Two small blocks of charges ( 5 mu C ) and
( 3 mu C ) are kept on a rough surface ( (mu= )
0.5) at a separation of 0.1 m. Find the
separation between the blocks when
they come to rest.
A . ( 0.27 mathrm{m} )
в. 0.6 т
c. ( 0.72 m )
D. 1.27 m
12
144Assertion
Acceleration of charged particle in nonuniform electric field does not depend on velocity of charge particle.
Reason
Charge is an invariant quantity. That is amount of charge on particle does not depend on frame of reference.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
145( n ) charged drops, each of radius ( r ) and
charge ( q, ) coalesce to form a big drop of
radius ( R ) and charge ( Q . ) If ( V ) is
the electric potential and ( boldsymbol{E} ) is the electric field at the surface of a drop,
then :
A ( cdot E_{text {big}}=n^{2 / 3} E_{text {small}} )
B. ( V_{text {big}}=n^{1 / 3} V_{text {small}} )
C. ( E_{text {small}}=n^{2 / 3} E_{text {big}} )
D. ( V_{text {big}}=n^{2 / 3} V_{text {small}} )
12
146Two equations are given below:
A) ( oint overline{boldsymbol{E}} cdot boldsymbol{d} overline{boldsymbol{A}}=frac{boldsymbol{Q}}{boldsymbol{E}_{0}} )
B) ( oint overline{boldsymbol{B}} cdot boldsymbol{d} overline{boldsymbol{A}}=mathbf{0} )
A. A – Ampere’s law B – Gauss law for electricity
B. A – Gauss law for electric fields B – Gauss law for magnetic fields
C . A – Faraday law B-Gauss law for electric fields
D. Both (A) and
12
147Show that the equilibrium is unstable.12
148A positively charged ball hangs from a silk thread. We put a positive test
charge ( q_{0} ) at a point and measure ( F / q_{0} ) then it can be predicted that the electric field strength E.
( A cdot>F / q_{0} )
в. ( =F / q )
c. ( <F / q_{0} )
D. Cannot be estimated
12
149A soild sphere of radius ( boldsymbol{R}_{1} ) and volume
charge density ( rho=frac{rho_{0} o}{r} ) is enclosed by a
hollow sphere of radius ( R_{2} ) with
negative surface charge density ( sigma ), such
that the total charge in the system is
zero. ( rho_{0} ) is a positive constant and ( r ) is the distance from the center of the
sphere.Then the ratio ( boldsymbol{R}_{2} / boldsymbol{R}_{1} ) is
( A cdot sigma / rho_{o} )
B. ( sqrt{2 sigma} / rho_{o} )
c. ( sqrt{rho_{-} o} / quad 2 sigma )
D. ( rho_{o} / sigma )
12
150Three charger ( q . Q ) and ( 4 q ) are placed in
a straight, line of length ( L ) at points
distant ( 0, L / 2 ) and ( L ) respectively from one end in other to make the net force
on ( q ) zero the charge ( Q ) must be eqyal to:
A. ( -q )
в. ( 2 q )
c. ( -frac{q}{2} )
D. ( q )
12
151A gold leaf electroscope can be used to:
A. detect the presence of charge only
B. test the kind of charge only
C. measure the charge only
D. detect the presence of charge and test the kind of charge
12
152The angle between electric dipole moment ( P ) and the electric field ( E ) when
the dipole is in stable equilibrium is
A . 0
B. ( frac{pi}{4} )
( c cdot frac{pi}{2} )
D. ( pi )
12
153(a) Write Gauss’ law for magnetism in the form of Maxwell’s equation.
(b) Write the value of ( frac{1}{sqrt{mu_{0} varepsilon_{0}}} )
12
154toppr
the force acting on particle ( A ? )
( mathbf{A} )
( B )
( mathbf{C} )
D.
( E )
12
155An imbalance of electric charges within or on the surface of a material is
A. current electricity
B. an electromagnetic wave
c. static electricity
D. None of these
12
156An electroscope has a charged rod brought near it, but not touching, and
the leaves open, Fig.I. Then a ground wire is attached to the electroscope and the leaves close, Fig. II. Finally, the ground wire and then the rod are
removed. It is determined that the
electroscope leaves have a net positive charge. Determine the charge of the rod and leaves in Fig. 1:
A. The rod has a net positive charge while the leaves have net negative charge
B. The rod has a net negative charge while the leaves have a net positive charge
c. Both have a negative charge
D. It is impossible to determine with the given information
12
157Two electric lines of force never
intersect.
A . True
B. False
12
158State whether given statement is True or False

Innermost electrons are free to move:
A. True
B. False

12
159Two point charges ( q_{1} ) and ( q_{2} ) are fixed at position vectors ( 4 hat{i} ) and ( 3 hat{j} ) respectively.
If a third charge ( q_{3} ) is in electrostatic equilibrium, then the position vector of
( q_{3} ) may be :
This question has multiple correct options
A . ( 2 hat{i}+1.5 hat{j} )
B . ( -2 hat{i}+4.5 hat{j} )
c. ( 4 hat{i}+3 hat{j} )
D. ( 3 hat{i}+4 hat{j} )
12
160If the dipole is place in a non-uniform
electric field an angle ( theta, ) in addition
tarque
A. Experiences a force
B. Experiences a repulsive force
c. No any kind of force
D. Neither attractive nor repulsive force
12
161An ebonite rod held in hand can be
charged by rubbing with flannel but a copper rod cannot be charged like this. Why?
12
162Charge ( Q, 2 Q ) and ( 4 Q ) are uniformly
distributed in three dielectric solid
spheres 1,2 and 3 of ( operatorname{radii} R / 2, R ) and
( 2 R ) respectively, as shown in figure. If
magnitudes of the electric field at point
( P ) at a distance ( R ) from the centre of
spheres 1,2 and 3 are ( E_{1}, E_{2} ) and ( E_{3} )
respectively, then
( mathbf{A} cdot E_{1}>E_{2}>E_{3} )
B ( cdot E_{3}>E_{1}>E_{2} )
( mathbf{c} cdot E_{2}>E_{1}>E_{3} )
( mathbf{D} cdot E_{3}>E_{2}>E_{1} )
12
163A tube of length L is filled completely with an incompressible liquid of mass M and closed at both the ends. The tube
is then rotated in a horizontal plane about one of its ends with a uniform
angular velocity ( omega . ) The force exerted by the liquid at the other ends is:-
A ( cdot frac{M L omega^{2}}{2} )
B. ( frac{M L^{2} omega}{2} )
c. ( M L omega^{2} )
D. ( frac{M L^{2} omega^{2}}{2} )
12
164A work of ( 200 J ) is done in moving a charge of ( -5 C ) from infinity to a
particular point in an electrostatic field The potential of this point is………..
( mathbf{A} cdot-20 V )
в. ( -25 V )
c. ( -30 V )
D. ( -40 V )
12
165If ( vec{E}=3 hat{i}+4 hat{j}-5 hat{k}, ) calculate the
electric flux through a surface of area 50 units in z-x plane
12
166A charge ( q ) is to be distributed on two conducting spheres. What should be the value of the charges on the spheres so that the repulsive force between them is maximum when they are placed at a fixed distance from each other in air?
A ( cdot frac{q}{2} ) and ( frac{q}{2} )
в. ( frac{q}{4} ) and ( frac{3 q}{4} )
c. ( frac{q}{3} ) and ( frac{2 q}{3} )
D. ( frac{q}{5} ) and ( frac{4 q}{5} )
12
167Two copper spheres of the same radii,
one hollow and the other solid, are
charged to the same potential, then
A. hollow sphere holds more charge
B. solid sphere holds more charge
c. both hold equal charge
D. we cant say
12
168Two infinitely large sheets having
charge densities ( sigma_{1} ) and ( sigma_{2} ) respectively
( left(sigma_{1}>sigma_{2}right) ) are placed near each other
separated by distance ( d . A ) charge ( q ) is placed in between two plates such that there is no effect on charge distribution on plates. Now this charge is moved at
an angle of ( 45^{circ} ) with the horizontal
towards plate having charge density ( sigma_{2} ) by distance ( a(a<d) . ) Find work done
by electric field in the process.
12
169The dimensional formula for electric
flux is
A ( cdotleft[M L^{3} I^{-1} T^{-3}right. )
B ( cdotleft[M^{2} L^{2} I^{-1} T^{-2}right] )
C . ( left[M L^{3} I^{1} T^{-3}right] )
( mathbf{D} cdotleft[M L^{-3} I^{-1} T^{-3}right] )
12
170A spherical conducting shell of inner
radius ( r_{1} ) and outer radius ( r_{2} ) has a
charge ( Q . A ) charge ( -q ) is placed at the
center of the shell. The surface of the
shell will be
A ( cdot frac{q}{4 pi r_{1}^{2}} ) and ( frac{Q}{4 pi r_{2}^{2}} )
В. ( frac{-q}{4 pi r_{1}^{2}} ) and ( frac{Q+q}{4 pi r_{2}^{2}} )
c. ( frac{q}{4 pi r_{1}^{2}} ) and ( frac{Q-q}{4 pi r_{2}^{2}} )
D. 0 and
12
171The electric field strength produced at a point some distance away from a source charge does NOT depend on:
A. The magnitude of the source charge
B. The sign of the source charge
c. The distance from the source charge
D. The nature of the medium surrounding the source charge
E. None of the above
12
172The process due to which an uncharged body acquires electric charges when held near a charged body is called:
A. conduction
B. induction
c. convection
D. none of these
12
173A sample of HCl gas is placed in an electric field of ( 2.5 times 10^{4} N C^{-1} ). The
dipole moment of each HCl molecule is
( 3.4 times 10^{-30} mathrm{Cm} . ) Find the maximum
torque that can act on a molecule.
12
174Give three properties of electric charge.12
175( Q ) amount of electric charge is present
on the surface of a sphere having radius
( boldsymbol{R} ). Then electrical potential energy of this system is
( mathbf{A} cdot frac{K Q^{2}}{R^{2}} )
в. ( frac{K Q^{2}}{R} )
c. ( frac{1}{2} frac{K Q^{2}}{R} )
D. ( frac{1}{2} frac{K Q^{2}}{R^{2}} )
12
176Examples of non-conductors include
A. sulphur
B. phosphorus.
c. wood
D. all of these.
12
177State whether true or false.
Ebonite is a good conductor of electricity.
A. True
B. False
12
178A gold leaf electroscope is given a positive charge so that its leaves diverge. How is the divergence of leaves affected, when a negatively charged rod is brought near its disc?
A. divergence increases
B. divergence decreases
c. divergence remains same
D. can’t say
12
179A metal sphere of radius ( 1 mathrm{cm} ) is given a charge of ( 3.14 mu C . ) Find the electric
intensity at a point ( 1 mathrm{m} ) from the center
of the sphere.
12
180The coulombic force of attraction
between two charges increases with increase in the distance of separation between them.
A. True
B. False
12
181A charge ( q ) is moving with a velocity ( bar{v}_{1}= ) 1 ìm / ( s ) at a point in a magnetic field and experiences a force ( overline{boldsymbol{F}}_{mathbf{1}}=boldsymbol{q}[-mathbf{1} hat{boldsymbol{j}}+ )
( mathbf{1} hat{boldsymbol{k}}] boldsymbol{N} . ) If the charge is moving with a
velocity ( bar{v}_{2}=1 hat{j} m / s ) at the same point
it experiences a force ( overline{boldsymbol{F}}_{2}=boldsymbol{q}[mathbf{1} hat{boldsymbol{i}}-mathbf{1} hat{boldsymbol{k}}] boldsymbol{N} )
The magnetic induction ( bar{B} ) at that
point is
( mathbf{A} cdot(hat{i}+hat{j}+hat{k}) W b / m^{2} )
B ( cdot(hat{i}-hat{j}+hat{k}) W b / m^{2} )
( mathbf{c} cdot(-hat{i}+hat{j}-hat{k}) W b / m^{2} )
D. ( (hat{i}+hat{j}-hat{k}) W b / m^{2} )
12
182The electric field in a region is radially outwards and has a magnitude ( boldsymbol{E}=boldsymbol{K} boldsymbol{r} )
The charge contained in a sphere of radius ( a ) is :
A. ( K 4 pi varepsilon_{0} a^{2} )
В ( cdot quad K frac{4}{3} pi varepsilon_{0} a^{3} )
c. ( K 4 pi varepsilon_{0} a^{3} )
D. none of these
12
183Two conducting spheres of radii ( r_{1} ) and
( r_{2} ) are charged such that they have the same electric field on their surfaces.
The ratio of the electric potential at
their centres is :
A. ( sqrt{frac{r_{1}}{r_{2}}} )
в. ( frac{r_{1}}{r_{2}} )
c. ( frac{r_{1}^{2}}{r_{2}^{2}} )
D. none of the above
12
184The constant ( k ) in Coulomb’s law
depends upon
A. nature of medium
B. system of units
c. intensity of charge
D. both (a) and (b)
12
185An electric dipole is placed at the origin and is directed along the ( x ) -axis. At a point ( P, ) far away from the dipole,the electric field is parallel to the y-axis. OP makes an angle ( theta ) with the ( x ) -axis. Then,
A ( cdot tan theta=sqrt{3} )
B. ( tan theta=sqrt{2} )
( mathbf{c} cdot tan theta=1 )
D. ( tan theta=frac{1}{sqrt{2}} )
12
186Two infinitely long parallel conducting plates having surface charge densities ( +sigma ) and ( -sigma ) respectively, are separated
by a small distance. The medium
between the plates is vacuum. If ( varepsilon_{0} ) is
the dielectric permittivity of vacuum
then the electric field in the region between the plates is:
A. 0 volt ( / m )
в. ( sigma / 2 varepsilon_{0} ) volt ( / mathrm{m} )
c. ( sigma / varepsilon_{0} ) volt ( / mathrm{m} )
D. ( 2 sigma / varepsilon_{0} ) volt ( / mathrm{m} )
12
187The electric potential due to a small electric dipole at a large distance ( r )
from the centre of the dipole is
proportional to :
( A )
B. 1 /
c. ( 1 / r^{2} )
D. ( 1 / r^{3} )
12
188The electric flux emerging through the
closed surface ( S_{1} ) shown in figure which
intersects the spherical conductor ( boldsymbol{S} )
due to the presence of a positive charge
very near to conductor is:
A. Positive
B. Negative
c. zero
D. None of the above
12
189The test charge used to measure
electric field at a point should
be
A. infinitely large
B. vanishingly small
c. negative
D. zero
12
190A small conducting sphere of radius ( r ) is Iying concentrically with a bigger
hollow conducting sphere of radius ( boldsymbol{R} )
The bigger and smaller spheres are
charged with ( Q ) and ( q ) respectively
( (Q>q) . ) The two spheres are insulated
from one another. The potential difference between the spheres will be :
A ( cdot frac{1}{4 pi epsilon_{0}}left(frac{q}{r}-frac{Q}{R}right) )
В. ( frac{1}{4 pi epsilon_{0}}left(frac{q}{r}-frac{q}{R}right) )
( ^{mathbf{C}} cdot frac{1}{4 pi epsilon_{0}}left(frac{q}{r}+frac{Q}{R}right) )
D. ( frac{1}{4 pi epsilon_{0}}left(frac{q}{R}-frac{Q}{r}right) )
12
191A dipole of dipole moment ‘p’ is placed in non-uniform electric field along ( x ) axis. Electric field is increasing at the
rate of ( 1 ~ V m^{-1} . ) The force on dipole is:
( mathbf{A} cdot mathbf{0} )
в. ( 2 p )
c. ( p / 2 )
D.
12
192As shown in fig. if a charge ( +q ) is
carried from a point ( boldsymbol{A}left(boldsymbol{r}, mathbf{1} mathbf{3 5}^{circ}right) ) to point
( Bleft(r, 45^{circ}right) . ) If dipole moment is ( p ) then the
work done by the external agent is then
going to be
A . 0
В. ( frac{q p}{4 pi epsilon_{0} r^{2}} )
( c cdot frac{1}{4 pi epsilon_{0}} frac{sqrt{2} q p}{r^{2}} )
D. ( frac{1}{4 pi epsilon} frac{q p}{r^{2}} )
12
193A body has a total charge of ( 6.4 times 10^{-19} )
coulomb. It is :
A. possible
B. not possible
c. may or may not be possible
D. Data insufficient
12
194An inclined plane of length ( 5.60 m )
making an angle of ( 45^{circ} ) with the horizontal is placed in an uniform electric field ( boldsymbol{E}=mathbf{1 0 0} boldsymbol{V m}^{-1} . ) A particle
of mass ( 1 k g ) and charge ( 10^{-2} C ) is allowed to slide down from rest position
from maximum height of slope. If the
coefficient of friction is ( 0.1, ) the time
taken by the particle to reach the bottom is
( mathbf{A} cdot 1 s )
B. ( 1.41 s )
c. ( 2 s )
D. None of these
12
195Compute the electric flux through a square surface of edges ( 2 l ) due to a
charge ( +Q ) whose geometric centre is located on the ( x ) -axis at a
perpendicular distance ( l ) from the
centre of the square.
A ( cdot frac{Q}{epsilon_{0}} )
в. ( frac{Q}{2 epsilon_{0}} )
c. ( frac{Q}{4 epsilon_{0}} )
D. ( frac{Q}{6 epsilon_{0}} )
12
196Electric field intensity at points in between and outside two thin separated parallel sheets of infinite dimension with like charges of same surface charge density ( (sigma) ) are and
respectively
A ( cdot sigma / epsilon_{0}, sigma / epsilon_{0} )
в. ( 0, sigma / epsilon_{0} )
( c .0,0 )
D. ( sigma / varepsilon_{0}, 0 )
12
197A hemispherical body is placed in a uniform electric field E. What is the flux
linked with the curved surface if the
field is perpendicular to the curved surface at every points as in figure.
A ( cdot phi=E 4 pi R^{2} )
В. ( phi=E 2 pi R^{2} )
c. ( phi=E 7 pi R^{2} )
D. ( phi=E 9 pi R^{2} )
12
198A dipole consisting of ( +10 n C ) and ( -10 n C ) separated by a distance of ( 2 mathrm{cm} ) oscillates in an electric filed of strength ( 60,000 mathrm{Vm}^{-1} . ) The frequency of its
oscillation is (Moment of inertia about the axis of oscillations is ( 3 times 10^{-10} mathrm{kgm}^{2} ) ):
A . ( 20.2 mathrm{Hz} )
в. ( 25.4 mathrm{Hz} )
c. ( 31.38 H z )
D. ( 37.1 mathrm{Hz} )
12
199Two points ( A ) and ( B ) are located at distance of ( 100 mathrm{cm} ) from on electric
dipole. A is sn axial point while B is in perpendicular bisector. The electric field intensity at ( A ) is ( vec{E} ). Then the intensity at B will be
( A cdot vec{E} )
в. ( 2 vec{E} )
( c cdot-vec{E} )
D. ( -frac{vec{E}}{2} )
12
200000

What
12
201The electric field of a plane polarized electromagnetic Wave in free space at time ( t=0 ) i given by an expression ( overrightarrow{boldsymbol{E}}(boldsymbol{x}, boldsymbol{y})=10 hat{j} cos [(boldsymbol{6} boldsymbol{x}+boldsymbol{8} boldsymbol{z})] )
The magenetic field ( vec{B}(x, z, t) ) is given by ; (c is the velocity of light will be:
A ( cdot frac{1}{c}(4 hat{k}+8 hat{i}) cos [(2 x-8 z+20 c t)] )
B ( cdot frac{1}{c}(6 hat{k}-8 hat{i}) cos [(6 x+8 z-10 c t)] )
c. ( frac{1}{c}(5 hat{k}+8 hat{i}) cos [(6 x+8 z-80 c t) )
D ( cdot frac{1}{c}(4 hat{k}-8 hat{i}) cos [(6 x+8 z+70 c t)] )
12
202Electric ield on the axis of small electric dipole at a distance ( r ) is ( vec{E}_{1} ) and ( vec{E}_{2} ) at ( a ) distance ( 2 mathrm{r} ) on a line of perpendicular dissector. Then
( ^{mathbf{A}} cdot vec{E}_{2}=-frac{vec{E}_{1}}{8} )
( mathbf{c} cdot underset{E_{2}}{overrightarrow{4}}=-frac{vec{E}_{1}}{_{1}} )
12
203The electric flux over the surface of a
sphere if it is charged with ( 10 mu C ) is
A ( cdot 36 pi times 10^{4} quad N m^{2} / C )
B . ( 36 pi times 10^{-4} quad N m^{2} / C )
( begin{array}{ll}text { C. } 36 pi times 10^{6} & text { N } m^{2} / Cend{array} )
D. ( 36 pi times 10^{-6} quad mathrm{Nm}^{2} / mathrm{C} )
12
204A cubical region of side a has its centre
at the origin. It encloses three fixed point charges,- -q ( a t(0,-a / 4,0),+3 q ) at (0,0,0) and ( -q ) at ( (0,+a / 4,0) . ) Choose the correct
option(s):

This question has multiple correct options
A. The net electric flux crossing the plane ( x=+a / 2 ) is equal to the net electric flux crossing the plane ( x=-a / 2 )
B. The net electric crossing the plane ( y=+a / 2 ) is more than the net electric flux crossing the plane ( y=-a / 2 )
C. The net electric flux crossing the entire region is ( frac{q}{varepsilon_{0}} )
D. The net electric flux crossing the piane ( z=+a / 2 ) is equal to the riet electric flux crossing the piane ( x= ) ( +a / 2 )

12
205Find the location of charge on the
conducting shell.
( mathbf{A} cdot+2 Q ) on the inner surface at ( r=a, Q ) on the outer
surface of the conductor at ( r=b )
B. ( -2 Q ) on the inner surface at ( r=a, Q ) on the outer
surface of the conductor at ( r=b )
C. ( +2 Q ) on the inner surface at ( r=a, 3 Q ) on the outer
surface of the conductor at ( r=b )
D. ( -2 Q ) on the inner surface at ( r=a, 3 Q ) on the outer
surface of the conductor at ( r=b )
12
206Which of the following is a good conductor of heat?
A. steel
B. Glass
c. wood
D. Rubber
12
207A charge ( q_{o} ) is distributed uniformly on a ring of radius R. A sphere of equal
radius R isconstructed with its centre
on the circumference of the ring. Find the electric flux through the surface of
the sphere.
A ( cdot frac{q_{0}}{3 varepsilon_{0}} )
в. ( frac{q_{0}}{2 varepsilon_{0}} )
c. ( frac{2 q_{0}}{varepsilon_{0}} )
D. ( frac{4 q_{0}}{3 varepsilon_{0}} )
12
208State and explain coulomb’s inverse
square law
12
209The force of attraction between two
charges ( 8 mu C ) and ( 0.2 N . ) Find the
distance of separation.
A. 412 meter
B. 1.2 meter
c. 120 meter
D. 0.12 meter
12
210Two concentric, thin metallic spherical
shells of radii ( R_{1} ) and ( R_{2}left(R_{1}>R_{2}right) ) bear
charges ( Q_{1} ) and ( Q_{2} ) respectively. Then the
potential at radius ‘r’ between ( R_{1} ) and ( R_{2} )
will be ( frac{1}{4 pi epsilon_{0}} ) times
A ( cdot frac{Q_{1}+Q_{2}}{r} )
В ( cdot frac{Q_{1}}{R_{1}}+frac{Q_{2}}{r} )
c. ( frac{Q_{1}}{R_{1}}+frac{Q_{2}}{R_{2}} )
D. ( frac{Q_{1}}{R_{2}}+frac{Q_{2}}{R_{2}} )
12
211An electric dipole of length ( 20 mathrm{cm} ) having ( pm 3 times 10^{-3} C ) charge placed at ( 60^{circ} ) with
respect to a uniform electric field
experiences a torque of magnitude ( 6 N m . ) The potential energy of the dipole
is
A. ( -2 sqrt{3} J )
( J )
B. ( 5 sqrt{3} J )
c. ( -2 sqrt{2} J )
D. ( 3 sqrt{5} )
12
212State whether true or false:
Gauss law is applicable only when there is a symmetric distribution of charge.
A. True
B. False
12
213A single electron has change ( |e|= )
( mathbf{1 . 6} times mathbf{1 0}^{-19} mathbf{C} . ) If the current passing
through a conducting wire is ( 0.32 A ) how many electrons would pass through
the wire In one hour?
A. ( 7.2 times 10^{20} )
В. ( 7.2 times 10^{21} )
c. ( 7.2 times 10^{19} )
D. ( 2 times 10^{18} )
12
214How many electronic charges form 1
coulomb?
A. ( 9.1 times 10^{-31} )
B . ( 1.6 times 10^{18} )
c. ( 62.5 times 10^{17} )
D. ( 1.76 times 10^{11} )
12
215A particle with mass 2.0 mg and charge ( 3.0 mu C ) is in a region with uniform electric field of ( (mathbf{3} hat{boldsymbol{i}}+boldsymbol{4} hat{boldsymbol{j}}) boldsymbol{N} / boldsymbol{C} ). The
acceleration of the particle will be:
A ( cdot(3 hat{i}+4 hat{j}) m / s^{2} )
B ( cdot(1.5 hat{i}+2 hat{j}) m / s^{2} )
( mathbf{c} cdot(4.5 hat{i}+6 hat{j}) m / s^{2} )
D. ( (2 hat{i}+3 hat{j}) m / s^{2} )
12
216A point charge ( Q ) is located at the center of the hollow spherical conductor of
the conductor being uncharged initially The potential at the inner surface will
be
A ( cdot K Qleft[frac{1}{R_{1}}+frac{1}{R_{2}}right] )
В ( cdot K Qleft[frac{1}{R_{1}}-frac{1}{R_{2}}right] )
c. ( K Qleft[frac{1}{R_{2}}-frac{1}{R_{1}}right] )
D. None of these
12
217A point charge ( q ) is located at the point ( (0,0,-a) . ) Consider a hemispherical surface of radius ‘a’ with its centre at
the origin and ( z geq 0 . ) The modulus of the electric flux through the hemispherical
surface is:
A ( cdot q / €_{0} )
B ( cdot q /left(2 sqrt{2} in_{0}right) )
( ^{mathbf{c}} cdotleft(1-frac{1}{sqrt{2}}right) q / epsilon_{0} )
D ( left(1-frac{1}{sqrt{2}}right) q /left(2 in_{0}right) )
12
218Why do insulators take larger time to
heat up?
A. They need more heat per every degree Celsius rise in temperature
B. They need more energy per every degree Celsius rise in temperature
C. They need more to perform more work per every degree Celsius rise in temperature.
D. They need more heat per every degree Farenheit rise in temperature
12
219If a dipole of dipole moment ( vec{p} ) is placed in a uniform electric field ( vec{E} ), then
torque acting on it is given by :
( mathbf{A} cdot vec{tau}=vec{p} cdot vec{E} )
В . ( vec{tau}=vec{p} times vec{E} )
C ( cdot vec{tau}=vec{p}+vec{E} )
D . ( vec{tau}=vec{p}-vec{E} )
12
220Infinite charges of magnitude ( q ) each
are lying at ( boldsymbol{x}=mathbf{1}, mathbf{2}, mathbf{4}, mathbf{8}, dots dots dots ) metre on
X-axis. The value of intensity of electric
field at point ( x=0 ) due to these
charges will be
A ( cdot 12 times 10^{9} q N / C )
в. zero
c. ( 6 times 10^{9} q N / C )
D. ( 4 times 10^{9} q N / C )
12
221Two concentric thin metallic spheres of
radii ( boldsymbol{R}_{1} ) and ( boldsymbol{R}_{2}left(boldsymbol{R}_{1}>boldsymbol{R}_{2}right) ) bear charges
( Q_{1} ) and ( Q_{2} ) respectively. Then the
potential at a radius ( r ) between ( R_{1} ) and
( boldsymbol{R}_{2} ) will be ( 1 / 4left(pi varepsilon_{0}right) ) times:
A. ( frac{Q_{1}+Q_{2}}{4} )
в. ( frac{Q_{1}}{R_{1}}+frac{Q_{2}}{r} )
c. ( frac{Q_{1}}{R_{1}}+frac{Q_{2}}{R_{2}} )
D. ( frac{Q_{1}}{R_{2}}+frac{Q_{2}}{R_{1}} )
12
222A conducting sphere is negatively charged. Which of the following
statements is true?
A. The charge is uniformly distributed throughout the entire volume
B. The charge is located at the center of the sphere
c. The charge is located at the bottom of the sphere because of gravity
D. The charge is uniformly distributed on the surface of the sphere
12
223In which position ( (A, B, C, text { or } D) ) of
second charge, the flux of the electric
field through the hemisphere remains uncharged? Explain.
12
224Electrostatic induction is used to
charge
A. Conductors
B. Semiconductors
c. Insulators
D. All of the above
12
225Two positive charges ( boldsymbol{q}_{1}=20 C ) and
( q_{2}=6 C ) are separated by diameter of
3 ( m ). Then what is the force produced by
them?
( A cdot 80 N )
B. ( 53.3 N )
( c .56 N )
D. ( 72.5 N )
12
226Two charged capacitors, have their outer plates fixed and inner plates connected by a spring of force constant
( k^{prime} . ) The charge on each capacitor is ( q ) Find the extension in the spring at equilibrium.
( ^{A} cdot frac{q^{2}}{2 A epsilon_{0} k} )
в. ( frac{q^{2}}{4 A epsilon_{6} k} )
c. ( frac{q^{2}}{A epsilon_{6} k} )
D. Zero
12
unırormiy aıstrıbutea tnrougnout ırs
volume

Which of the following expressions
gives the electric field strength at point
( P, ) a point that lies inside the sphere
and is a distance ( r ) from the center of
the sphere?
( ^{mathrm{A}} cdot_{E}=frac{Q r}{4 pi epsilon_{0} R^{3}} )
B. ( quad E=frac{Q}{4 pi epsilon_{0} r^{2}} )
c. ( E=0 ) (Point ( P ) is inside of a conductor.
‘D ( quad E=frac{3 Q r}{4 pi epsilon_{0} R^{3}} )
( E=frac{3 Q}{4 pi epsilon_{0} r^{3}} )

12
228How many megacoulombs of positive
charge are in 1.00 mol of neutral
molecular hydrogen ( operatorname{gas}left(boldsymbol{H}_{2}right) )
12
229The electric field in a region of space is given by ( mathrm{E}=5 mathrm{i}+2 mathrm{j} ) N/C. The electric flux
due to this field through an area ( 2 m^{2} )
lying in the YZ plane, in S.l unit, is
A . 10
B. 20
c. ( 10 sqrt{2} )
D. ( 2 sqrt{29} )
12
230State whether the following statements are True or False.
If ( mathrm{E}=0, ) at all points of a closed surface, The electric flux through the surface is zero.
A. True
B. False
12
231An infinitely long cylinder of radius
( mathrm{R}=2 mathrm{cm} ) carries a uniform charge density
( =18 mu mathrm{C} / mathrm{m} 3 )
Calculate the electric field at distance
( r=1 mathrm{cm} )
from the axis of the cylinder.
A. The magnitude of electric field intensity at the ( x x ) axis of charged body is ( left(frac{p r^{2}}{2 epsilon_{0} d}right) )
B. The magnitude of electric field intensity at the ( x x ) axis of charged body is zero.
C. The magnitude of electric field intensity at the yy axis of charged body is ( left(frac{p d^{2}}{2 epsilon_{0}}right) )
D. The magnitude of electric field intensity at the ( x x ) any point in the cavity is ( frac{p^{2}}{2 epsilon_{0}} d )
12
232The total flux passing through the cube
is:
( mathbf{A} cdot(B+C+D) L^{2} )
B . ( 2(B+C+D) L^{2} )
( mathbf{c} cdot 6(B+C+D) L^{2} )
D. zero
12
233A polythene piece rubbed with wool is
found to have a negative charge of ( 3 x ) ( mathbf{1 0}^{-mathbf{7}} mathbf{C} )
(a) Estimate the number of electrons
transferred (from which to which?)
(b) Is there a transfer of mass from wool
to polythene?
12
234Mud houses are cooler in summer and
warmer in winter because
A. mud is a good conductor of heat
B. mud is a superconductor of heat
c. mud is a bad conductor of heat
D. none of these
12
235A negatively charged particle is situated on a straight line joining two other stationary particles each having charge ( +q . ) The direction of the motion
of the negatively charged particle will
depend on:
A. the magnitude of charge
B. the position at which it is situated
c. both magnitude of charge and its position.
D. the magnitude of ( +q )
12
236Fill in the blanks.
A field normal to the plane of a circular
wire ( n ) turns and radius r which carries
a current I is measured on the axis of
the coil at small h distance h from the
centre of the coil. This is smaller than
the field at the centre by a friction
A ( cdot_{3} frac{3 h^{2}}{2 r^{2}} )
B. ( frac{h^{2}}{2 r^{2}} )
c. ( frac{4 h^{2}}{2 r^{2}} )
D. ( frac{3 h^{2}}{2 r^{2}} )
12
237Find the electric field at ( z>0.5 d )
( mathbf{A} cdot E=0 )
B ( cdot E=-frac{sigma}{epsilon_{0}} hat{k} )
( mathbf{c} cdot E=frac{sigma}{epsilon_{0}} hat{k} )
D・ ( E=-frac{sigma}{2 epsilon_{n}} hat{k} )
12
238Figure shows a uniformly charged
hemisphere of radius R. It has a volume
charge density p. If the electric field at
point ( 2 R, ) above its center is ( E, ) then
what is the electric field at the point ( 2 R )
below its center?
( mathbf{A} cdot rho R / 6 varepsilon_{0}+E )
( mathbf{B} cdot rho R / 12 varepsilon_{0}-E )
( mathbf{c} cdot-rho R / 6 varepsilon_{0}+E )
( mathbf{D} cdot rho R / 12 varepsilon_{0}+E )
12
239The work done to move a charge on an equipotential surface is?
A . Infinity
B. Less than 1
c. Greater than 1
D. zero
12
240If the distance between two equal points charges is doubled and their individual charges are also doubled,
what would happen to the force between them?
12
241Identify the correct statement:
A. Electrostatic forces are much weaker than the gravitational forces.
B. Electrostatic forces are much stronger than the gravitational forces.
C . Electrostatic forces are comparable to the gravitational forces
D. All of the above
12
242Calculate the electrostatic force of
attraction between a proton and an electron in a hydrogen atom. The radius of the electron orbit is ( 0.05 mathrm{nm} ) and
charge on the electron is ( 1.6 times 10^{-9} C )
12
243In the diagram shown, the leaves of the electroscope diverge when a positively charged rod is brought near the knob of an uncharged electroscope. The leaves diverge because:
A. They are both negatively charged
B. They are both positively charged
c. One is positive and one is negative
D. One leaf is neutral and one is positive
E. Both leaves are neutral
12
244What is the direction of the electric field
directly south of a positive point charge due to the point charge?
A. North
B. South
( c . ) East
D. west
E. Down
12
245Mica is a ( _{—} ) conductor of electricity
A. good
c. positive
D. None of the above
12
246When a glass rod is rubbed with a silk cloth, charges appear on both. A similar phenomenon is observed with many other pairs of bodies. Explain how this observation is consistent with the law
of conservation of charge.
12
247ABCD is a square of 1 metre side of a
non-conducting material. Four metallic spheres of 4,5,8 and ( 10 mathrm{cm} ) diameters are placed at the four corners. All of
them are connected by a fine metallic wire and charge of 540 units is imparted to the system. The potential at the centre of the square is :
(in cgs system)
A ( cdot frac{540 sqrt{2}}{400} )
B. ( frac{540 sqrt{2}}{200} )
c. ( frac{540 sqrt{2}}{100} )
D. ( frac{540 sqrt{2}}{10} )
12
248A negatively charged body has
A. an excess of protons
B. an excess of electrons
C . an excess of photons
D. an deficiency of electrons
12
249Prove that potential at point on transverse (equatorial) position of electric dipole is zero.12
250The force between two short electric
dipole placed on the same axis at a distance ( R, ) varies as?
( mathbf{A} cdot R^{-1} )
B. ( R^{-2} )
( c cdot R^{-3} )
D. ( R^{-4} )
12
251The breakdown electric intensity for air is
( 3 times 10^{6} mathrm{V} / mathrm{m} . ) The maximum charge that
can be held by a sphere of radius ( 1 mathrm{mm} ) is
A ( .0 .33 C )
в. 0.33 пС
( c .3 .3 C )
D. ( 3.3 mu C )
12
252When a woman with long hair puts her hands on a Van de Graaff Generator
large conducting sphere with a conveyor belt delivering charge to it) her hair stands on end. Which of the
following best explains this phenomenon?
A. Like charges attract
B. Like charges repel
c. Her hair will not stand on end
D. Her body is conducting a current to the ground
E. The Van de Graff generator makes a magnetic field that draws her hair up on end
12
253An electric dipole of moment ‘p’ is placed in an electric field of intensity ‘E’. The dipole acquires a position such that the axis of the dipole makes an angle ( theta ) with the direction of the field. Assuming that the potential energy of the dipole to be zero when ( =90^{0}, ) the torque and the
potential energy of the dipole will respectively be
A. ( p E sin theta, p E cos theta )
B. ( p E sin theta,-2 p E cos theta )
c. ( p E sin theta, 2 p E cos theta )
D. ( p E cos theta,-p E cos theta )
12
254The magnitude of electric field intensity E, such electron, placed in the field, would experience an electric force equal to its weight is :
A ( cdot 5.6 times 10^{-7} N C^{-1} )
B . ( 5.6 times 10^{-8} N C^{-1} )
c. ( 5.6 times 10^{-10} N C^{-1} )
D. ( 5.6 times 10^{-11} mathrm{NC}^{-1} )
12
255When a glass rod is rubbed with silk
cloth, it acquires charge because:
A. Electrons are added to it
B. Electrons are removed from it
c. Protons are added to it
D. Protons are removed from it
12
256A proton (mass ( 1.67 times 10^{-27} mathrm{kg} ) ) on striking a neutron (mass nearly equal to the proton ) forms a deutron. What would be the velocity of the deutron if it is formed by a proton moving left with a velocity of ( 7.0 times 10^{6} mathrm{m} / mathrm{s} ) and a neutron
moving right with a velocity of ( 4.0 times 10^{6} ) ( mathrm{m} / mathrm{s} )
12
257The concept of solid angle is a natural extension of a ( underline{text { angle to }} ) dimensions.
( A ). plane, two
B. line, three
c. plane, three
D. line, two
12
258A body of mass ( mathrm{M} ) and charge q is
suspended from a string. When slightly displaced, it oscillates with period T. If a uniform electric field acts vertically downwards, then the new time period
will be:
A ( cdot T^{prime}=T )
в. ( T^{prime}T )
D. cannot be predicted
12
259A line formly changed eonducting sphere of ( 24 m ) diameter has a surface
change density of ( 80.0 mu c / m^{2} )
(i) Find the charge on the sphere
(ii) What is the total electric flux learning the surface of the sphere?
A ( cdot 1.447 times 10^{-3} c, 1.63 times 10^{8} frac{N m^{2}}{C} )
В. ( _{2.447} times 10^{-3} c, 1.63 times 10^{8} frac{N m^{2}}{C} )
c. ( _{1.447} times 10^{-3} c, 2.63 times 10^{8} frac{N m^{2}}{C} )
D. ( 41.447 times 10^{-3} c, 1.63 times 10^{8} frac{N m^{2}}{C} )
12
260Point charge ( q_{0} ) is placed inside a cone of base radius ‘R’, x distance below
centre of the top surface as shown in figure.Find electric flux related to
curved surface of the cone:-
A ( cdot frac{q}{2 varepsilon_{0}} )
в. ( frac{q}{varepsilon_{0}}-frac{q}{2 varepsilon_{0}}left(1-frac{x}{sqrt{R^{2}+x^{2}}}right) )
c. ( frac{q}{varepsilon_{0}}left(1-frac{x}{sqrt{R^{2}+x^{2}}}right) )
D. ( frac{q}{varepsilon_{0}} timesleft(frac{x}{sqrt{R^{2}+x^{2}}}right) )
12
261An electron at rest gives rise to only
A. Magnetic field
B. Electric field
C. Both electric and magnetic field
D. Neither electric field nor magnetic field
12
262spheres of radii ‘a’ and ‘b’, respectively(see figure), has volume charge density ( rho=frac{A}{r}, ) where ( A ) is a
constant and ( r ) is the distance from the
centre. At the centre of the spheres is a
point charge ( Q . ) The value of ( A ) such that
the electric field in the region between
the spheres will be constant, is :
A ( cdot frac{Q}{2 pi a^{2}} )
В. ( frac{Q}{2 pileft(b^{2}-a^{2}right)} )
c. ( frac{2 Q}{pileft(a^{2}-b^{2}right)} )
( D cdot frac{2 Q}{pi^{2}} )
12
263A circle, having radius “r” has line charge distribution over its
circumference having linear charge
density ( lambda=lambda_{0} cos ^{2} theta . ) Calculate the
total electric charge residing on the
circumference of the circle.
( left[int_{0}^{2 pi} cos ^{2} theta d theta=piright] )
12
264Four charges are rigidly along the Y axis as shown. A positive charge approaches the system along the X axis with initial
speed just enough to cross the origin. Then its total energy at the origin is
A. zero
B. positive
C . negative
D. data insufficient
12
265If ( g_{E} ) and ( g_{M} ) are the accelerations due
to gravity on the surfaces of the Earth and the Moon respectively and if Millikan’s oil drop experiment could be performed on the two surfaces, one will find the ratio (electronic charge on the Moon/ electronic charge on the Earth) to be:
A . 1
B.
( mathbf{c} cdot g_{E} / g_{M} )
D. ( g_{M} / g_{E} )
12
266A small electric dipole is placed at origin with its axis being directed along the positive x-axis. The direction of
electric field due to the dipole at a point ( (1 mathrm{m}, sqrt{2} mathrm{m}, 0) ) is along the:
A . z-axis
B. y-axis
c. x-axis
D. line ( y=x )
12
267An infinitely long wire is kept along z-
axis from ( z=-infty ) to ( z=+infty, ) having
uniform linear charge density ( frac{10}{9} n C / m . ) The electric field ( vec{E} ) at point ( (6 mathrm{cm}, 8 mathrm{cm}, 10 mathrm{cm}) ) will be:
( A cdot(160 i+120 j+200 k) N / C )
B. (200 k) N/C
( c cdot(160 i+120 j) N / c )
D. ( (120 mathrm{i}+160 mathrm{j}) mathrm{N} / mathrm{C} )
12
268Cups are not made of metals. The
reason is:
A. Metals are good conductors
c. Metals are expensive
D. None of the above
12
269Select the odd one out w.r.t. conduction
of heat (gold, silver, copper, asbestos)
A . asbestos
B. gold
c. silver
D. copper
12
270Eight dipoles of charges of magnitude ( q ) are placed inside a cube. Then, the total electric flux coming out of the cube will be
A ( cdot frac{8 q}{epsilon} )
в. ( frac{16 q}{epsilon} )
c. ( underline{q} )
D.
12
271Find the electric field both inside the
shell at a distance ( r ) from the centre.
( ^{A} cdot frac{Q}{4 pi epsilon_{0} a^{2}} )
в. ( frac{Q r}{4 pi epsilon_{0} a^{2}} )
c. ( frac{Q}{4 pi epsilon_{0} a^{3}} )
D. ( frac{Q r}{4 pi epsilon_{0} a^{3}} )
12
272Inspite of mutual repulsion between the
protons and no electric force between
neutrons, a number of protons and
neutrons do stay together to form stable nuclei. Which of the following are
reasons for this?
1. Another type of force, called nuclear
force works between these particles
when they are very close to each other
2. The neutrons keep the protons apart so that there is no repulsion between them
3. The nuclear force is always attractive
and does not depend on the charge of
the particles
Select the correct answer from the
codes given.
( A cdot 2 ) and 3 only
B. 1 and 2 only
c. 1,2 and 3
D. 1 and 3 only
12
273What is the angle between the electric
dipole moment and the electric field due to it on the axial line?
A ( cdot 0^{circ} )
B. ( 90^{circ} )
( c cdot 180^{circ} )
D. none of these
12
274Two identical charged spheres suspended from a common point by two massless strings of length I are initially a distance ( d(d<<I) ) apart because of their mutual repulsion. The charge begins to leak from both the spheres at a constant rate. As a result the charges approach each other with a velocity v. Then as a function of distance ( x )
between them
A ( . v propto x^{-1 / 2} )
B. ( v propto x^{-1} )
( mathbf{C} cdot v propto x^{1 / 2} )
D. ( v propto x )
12
275Choose the correct statement.
A. Polar molecules have permanent electric dipole moment.
B. ( C O_{2} ) molecule is a polar molecule.
C ( . H_{2} O ) is a non-polar molecule.
The dipole field at large distances falls of as ( frac{1}{r^{2}} )
12
276Two point charges ( q ) and ( -q ) are separated by a distance 2l, Find the flux of electric field strength vector across the circle of radius ( mathrm{R} ) placed with its centre coinciding with the midpoint of line joining the two charges in the perpendicular plane.12
277The device, which can be used to detect whether an object is charged, is:
A. telescope
B. microscope
c. electroscope
D. none of the above
12
278A point charge ( q ) is kept at a distance of 2R from centre of an uncharged spherical shell of radius R. The potential at centre of the shell due to charges induced on shell is
A ( cdot frac{q}{4 pi E_{0} R} )
В ( cdot frac{q}{4 pi E_{0} 2 R} )
c. ( frac{-q}{4 pi E_{0} R} )
D. zero
12
279A hollow cylinder has a charge ( q )
coulomb within it. If ( phi ) is the electric flux in units of voltmeter associated
with the curved surface ( B ), the flux
linked with the plane surface ( A ) in units
of voltmeter will be
A ( cdot frac{q}{epsilon_{0}}-phi )
B ( cdot frac{1}{2}left(frac{q}{epsilon_{0}}-phiright) )
c. ( frac{q}{2 epsilon_{0}} )
D. ( frac{phi}{3} )
12
280A uniform vertical electric field ( boldsymbol{E} ) is
established in the space between two large parallel plates. A small conducting sphere of mass ( boldsymbol{m} ) is suspended in the field from a string of
length ( L ). If the sphere is given ( a+q ) charge and the lower plate is charged positively, the period of oscillation of this pendulum is :
( ^{mathrm{A}} cdot 2 pi sqrt{frac{L}{g}} )
в. ( 2 pi sqrt{frac{L}{g+frac{q E}{m}}} )
c. ( _{2 pi} sqrt{frac{L}{g-frac{q E}{m}}} )
D. ( 2 pi sqrt{frac{L}{left(g^{2}+left(frac{q E}{m}right)^{2}right)^{1 / 2}}} )
12
281Let ( boldsymbol{E}_{1}(boldsymbol{r}), boldsymbol{E}_{2}(boldsymbol{r}) ) and ( boldsymbol{E}_{3}(boldsymbol{r}) ) be the
respective electric fields at a distance from a point charge ( Q, ) an infinitely long wire with constant linear charge density
( lambda, ) and an infinite plane with uniform
surface charge density ( sigma . ) If ( E_{1}left(r_{0}right)= )
( E_{2}left(r_{0}right)=E_{3}left(r_{0}right) ) at a given distance ( r_{0} )
then :
A ( cdot Q=4 sigma pi r_{0}^{2} )
B. ( r_{0}=frac{lambda}{2 pi sigma} )
c. ( E_{1}left(frac{r_{0}}{2}right)=2 E_{2}left(frac{r_{0}}{2}right) )
D. ( E_{2}left(frac{r_{0}}{2}right)=4 E_{3}left(frac{r_{0}}{2}right) )
12
282An electric dipole has the magnitude of its charge as ( q ) and its dipole moment is
p. It is placed in a uniform electric field
E. If its dipole moment is along the direction of the field, the force on it and
its potential energy are respectively:
A. q. E and p. E
B. zero and minimum
c. q. E and maximum
D. 2q. E and minimum
12
283Consider a uniform electric field ( boldsymbol{E}= )
( 3 times 10^{3} hat{i} N / C . ) What is the flux of this
field through a square of ( 10 mathrm{cm} ) on a side whose plane is parallel to the yz plane?
A ( cdot 30 mathrm{Nm}^{2} / mathrm{C} )
В. ( 40 mathrm{Nm}^{2} / mathrm{C} )
c. ( 50 N m^{2} / C )
D. ( 60 mathrm{Nm}^{2} / mathrm{C} )
12
284An electron is moving in a uniform
horizontal electric field. If the
acceleration of electron is ( 45^{circ} )
downward to the horizontal, then the field intensity in newton/coloumb will
be
12
285Two equal charges are separated by a
distance ( d . A ) third charge placed on a
perpendicular bisector at ( x ) distance will experience maximum coulomb force when :
A ( cdot x=frac{d}{sqrt{2}} )
B. ( x=frac{d}{2} )
c. ( _{x}=frac{d}{2 sqrt{2}} )
D. ( _{x}=frac{d}{2 sqrt{3}} )
12
286Consider a hemispherical surface of
radius ( r, ) a positive point charge ( q ) is kept at the centre of hemisphere. The electric flux through this hemisphere is
A . zero
в. ( frac{q}{varepsilon_{0}} )
c. ( frac{q}{2 varepsilon_{0}} )
D. ( frac{2 q}{varepsilon_{0}} )
12
287The figure shows the electric field lines
a round a conductor.
(a) At which of the four points is the
field strongest?
(b) At which point is there a negative
charge?
12
288Mark the correct options
A. Gauss law is valid only for unsymmetrical charge distributions
B. Gauss law is valid only for charge placed in vacuum
C. The electric field calculated by Gauss law is the field due to the charges outside the Gaussian surface
D. The flux of the electric field through a closed surface due to all the charges is equal to the flux due to the charges enclosed by the surface
12
289Net charge within an imaginary cube drawn in a uniform electric field is
always zero. Is this statement true or false.
12
290An electric dipole as shown is free to
move and rotate.lt will
A. Rotate clock – wise and move to the left
B. Rotate anti clock wise and move to the right
C. Rotate clock wise and move to the right
D. Rotate anticlockwise and move to the left
12
291Positive electric flux indicates that
electric lines of force are directed
A. outwards
B. inwards
c. either (a) or (b)
D. none of these
12
292A linear charge having linear charge
density ( lambda ), penetrates a cube diagonally
and then it penetrate a sphere diametrically as shown. What will be the ration of flux coming out of cube and
sphere.
( ^{A} cdot frac{1}{2} )
в. ( frac{2}{sqrt{3}} )
c. ( frac{sqrt{3}}{2} )
( D )
12
293The gold leaf electroscope is charged so that its leaves somewhat diverge. If ( X ) rays are incident on the electroscope
then
A. the divergence will decrease
B. the divergence of leaves will remain unchanged
c. the gold leaves will melt
D. the divergence will increase
12
294What happens when some charge is placed on a soap bubble?
c. The bubble collapses
D. None of these
12
295A closed surface S is constructed
around a conducting wire connected to
a battery and switch (Fig) As the switch
is closed, the free electrons in the wire
start moving along the wire. In any time
interval, the number of electrons
entering the closed surface ( S ) is equal to
the number of electrons leaving it. After
closing the switch, the flux of the
electric field through the closed surface
will :
This question has multiple correct options
A. increase
B. decrease
C. remain unchanged
D. be zero
12
296A hollow spherical conducting shell of
inner radius ( r_{1} ) and other radius ( r_{2} ) has
a charge ( Q . A ) charge ( -q ) is placed at the centre of the sphere. The surface charge densities on the inner and outer
surfaces of the sphere will be
respectively:-
( ^{mathbf{A}} cdot frac{q}{4 pi r_{1}^{2}} ) and ( frac{q}{4 pi r_{2}^{2}} )
В ( cdot frac{-q}{4 pi r_{1}^{2}} ) and ( frac{Q+q}{4 pi r_{2}^{2}} )
c. ( frac{q}{4 pi r_{1}^{2}} ) and ( frac{Q-q}{4 pi r_{2}^{2}} )
D. ( _{text {O and }} frac{Q-q}{4 pi r_{2}^{2}} )
12
297Calculate the charge on a body if ( 10^{5} ) electrons have been added to it
( mathbf{A} cdot-1.6 times 10^{-14} C )
В. ( 1.6 times 10^{-14} C )
c. ( 1.6 times 10^{14} C )
D. ( -1.6 times 10^{14} C )
12
298Derive the expression for torque acting on a dipole ( boldsymbol{tau}=boldsymbol{P} . boldsymbol{E} sin boldsymbol{theta} )12
299Negative electric flux indicates that electric lines of force are directed
A. outwards
B. inwards
c. either (a) or (b)
D. none of these
12
300Relative permittivity of water is ( 81 . ) If ( epsilon_{w} )
and ( epsilon_{0} ) are permittivities of water and
vacuum respectively, then :
A ( cdot epsilon_{0}=9 epsilon_{w} )
В . ( epsilon_{0}=81 epsilon_{w} )
( mathbf{c} cdot epsilon_{w}=9 epsilon_{0} )
D. ( epsilon_{w}=81 epsilon_{0} )
12
301Figure represents a negatively charged
gold leaf electroscope. Of the parts ( A, B ) C, D and E, state whether they are an
insulator or a conductor:
( A cdot A, B ) and ( E ) are conductors while ( D ) and ( C ) are insulators
B. B, D and E are conductors while A and C are insulators
( c . A, D ) and ( E ) are insulators while ( B ) and ( C ) are conductors
D. A, Dand E are conductors while B and C are insulators
12
302Gravitational force
of the medium between the charges.
A. depends
B. does not depend
c. sometimes depends
D. None of these
12
303Electric flux through a surface of area
( 100 m^{2} ) lying in the xy plane is (in ( V ) -m) if ( overrightarrow{boldsymbol{E}}=hat{boldsymbol{i}}+sqrt{mathbf{2}} hat{boldsymbol{j}}+sqrt{mathbf{3} hat{boldsymbol{k}}} )
A. 100
B. 141.4
c. 173.2
D. 200
12
304Which of the following statement is NOT
true?
A. lightning and spark from wollen clothing are essentially the same phenomena.
B. when you rub a plastic scale on your dry hair, it acquires a charge.
C. charge acquired by a glass rod when it is rubbed with silk is called as negative charge
D. static charges are called so, because they donot move by themselves
12
305The potential energy for a force field ( overrightarrow{boldsymbol{F}} ) is given by ( U(x, y)=sin (x+y) )
Magnitude of the force acting on the particle of mass ( m ) at ( left(0, frac{pi}{4}right) ) is
( A )
B. ( sqrt{2} )
c. ( frac{1}{sqrt{2}} )
D.
12
306A charge ( q ) is placed at the corner of a cube of side ( a ). The electric flux passing
through the cube is :
A ( cdot frac{q}{a varepsilon_{0}} )
в. ( frac{q}{varepsilon_{0} a^{2}} )
c. ( frac{q}{4 pi varepsilon_{0} a^{2}} )
D. ( frac{q}{24 varepsilon_{0}} )
12
307Two point charges ( +q ) and ( -q ) are placed at a distance ( x ) apart. A third charge is placed in such a way so that all the three charges are in equilibrium.
Then :
A. unknown charge is ( -4 q / 9 )
B. unknown charge is ( -9 q / 4 )
c. it should be at ( (x / 3) ) from smaller charge between them
D. none of the above
12
3084 charges are placed each at a distance
a’ from origin. The dipole moment of
configuration is :
A ( cdot 2 q a hat{j} )
в. ( 3 q a hat{j} )
( mathbf{c} cdot 2 a q[hat{i}+hat{j}] )
( 0 . ) none
12
309The charge on a body is +1 C. Find the number of electrons in excess or deficit
on the body.
A ( cdot 6.25 times 10^{1} ) coulomb
B. ( 6.25 times 10^{-18} ) coulomb
c. ( 6.25 times 10^{-1} ) coulomb
D. ( 6.25 times 10^{18} ) coulomb
12
310Four equal electric charges are arranged at the four corners of a square of side ( a . ) Out of these four charges, two
charges are positive and placed at the ends of one diagonal. The other two charges are positive and placed at the ends of the other diagonal. The energy of
the system is:
This question has multiple correct options
A. Negative
B. Positive
( ^{mathrm{C}} ). ( _{text {Less than }} frac{1}{4 pi varepsilon_{0}}left(frac{2 q^{2}}{a}right) )
Deater than ( frac{1}{4 pi varepsilon_{0}}left(frac{2 q^{2}}{a}right) )
12
311Two metal spheres ( A ) and ( B ) of exactly same mass are given equal positive and negative charges respectively. Their masses after charging:
A. Remains unaffected
B. Mass of ( A> ) mass of B
c. Mass of ( A< ) mass of ( B )
D. Nothing can be said
12
312Determine the electric dipole moment
of the system of three charges,placed on the vertices of an equilateral triangle as shown in the figure:
A ( cdot(q l) frac{hat{i}+hat{j}}{sqrt{2}} )
В ( cdot sqrt{3} q l frac{hat{j}-hat{i}}{sqrt{2}} )
( mathbf{c} .-sqrt{3} q l hat{j} )
D. ( 2 q l hat{j} )
12
313Drive an expression for Electric field due to an Electric dipole at a point on the axial line.12
314( mathrm{Q}(mathrm{charge})=? )
( mathbf{A} cdot n / e )
B. ( n e )
( c cdot e / n )
D. All
12
315How many point charges of same magnitude are required to constitute an electric dipole?12
316Two particles of charges and masses
( left(+q_{1}, m_{1}right) ) and ( left(-q_{2}, m_{2}right) ) are released at
two different points in a uniform electric field E established in free
space. If their separation remains unchanged find the separation ( l ) between them
12
317Identify the correct statement:
A. The electric potential on bigger sphere is higher
B. The electric potential on bigger sphere is lower
C. The electric potential on the two spheres is equal
D. None of these
12
318An early model for an atom considered
it to have a positively charged point
nucleus of charge ( Z e ), surrounded by a
uniform density of negative charge upto a radius ( R ). The atom as a whole is
neutral. The electric field at a distance ( r )
from the nucleus is ( (r<R) )
A ( cdot frac{Z e}{4 pi epsilon_{0}}left[frac{1}{r^{2}}-frac{r}{R^{3}}right] )
В ( cdot frac{Z e}{4 pi epsilon_{0}}left[frac{1}{r^{2}}-frac{r}{R^{2}}right] )
c. ( frac{Z e}{4 pi epsilon_{0}}left[frac{1}{R^{3}}-frac{r}{r^{2}}right] )
D. ( frac{Z e}{4 pi epsilon_{0}}left[frac{1}{R^{3}}+frac{r}{r^{2}}right] )
12
319A silver wire of ( 1 mathrm{mm} ) diameter has a
charge of 90 coulombs flowing in 1 hours and 15 minutes. Silver contains
12
320In above shown figure, a point charge ( +mathrm{Q} ) is fixed in position and five points are near the charge. An electric field is created by a point charge, then find out the point where the magnitude of the electric field would be least :
( A )
B. B
( c cdot c )
( D )
E.
12
321Force between two charges separated by a certain distance in air is ( mathrm{F} ). If each charge is doubled and the distance
between them is also doubled, force
would be
A. ( F )
в. ( 2 F )
( c cdot frac{F}{2} )
D. ( 3 F )
12
322The electric flux through the curve
surface of a cone. Due to a charge ( Q )
placed at its mouth,
A. ( phi=0 )
в. ( phi>frac{Q}{2_{varepsilon}} )
c. ( _{phi>frac{Q}{varepsilon_{0}}} )
D. ( phi=frac{Q}{z_{0}} )
12
323If a conductor has a potential ( V neq 0 )
and there are no charges anywhere else outside, then
A. there must be charges on the surface or inside itself
B. there cannot be any charge in the body of the conductor
c. there must be charges only on the surface
D. there must be charges inside the surface
12
324When an electron is moving parallel to
the conductor carrying current as
shown we get
A. region A has strong field
B. region B has weak field
C. region C has strong field
D. electron will move towards conductor
12
325If an electric dipole is placed inside a sphere filled with water, then among the following which statement is correct?
A. Water does not permit electric flux to enter into space
B. Electric flux entering into sphere is equals to electric flux leaving the sphere
c. Electric flux is coming towards the sphere
D. Electric flux is coming out of sphere
12
326Electric lines of force about a negative
point charge are:
A . circular, anti-clockwise
B. circular, clockwise
12
327The energy of a charged conductor is
given by the expression:
( mathbf{A} cdot q^{2} / 2 c )
B. ( q^{2} / c )
( mathbf{c} cdot 2 q c )
D. ( q / 2 c^{2} ),where q is charges on the conductor,c is its capacity
12
328A positive charge ( +Q ) is fixed at a point
A. Another positively charged particle of mass ( mathrm{m} ) and charge ( +mathrm{q} ) is projected from a point B with velocity u as shown in the figure. The point B is at a large distance from ( A ) and at a large distance d from the line AC. The initial velocity is parallel to the line AC. The point ( C ) is at very large distance from A. Find the minimum distance (in meter) of ( +q )
from ( +Q ) during the motion. ( [text { take } Q q= )
( left.4 pi epsilon_{0} m u^{2} dright] )
A. ( d(1+sqrt{2}) )
B . ( d(sqrt{2}-1) )
c. ( frac{d}{(1+sqrt{2})} )
D. ( frac{d}{(sqrt{2}-1)} )
12
329Two uniformly charged plates are pictured above, with four evenly spaced points shown along a horizontal lines between the plates.What is the correct
rank of strength of the electric field at the points, greatest first?
A. 1,2,3,4
B. 4, 3, 2,1
C. The electric field strength is the same at all points
D. 1 and 4 tie, 2 and 3 tie
( mathrm{E} cdot 2 ) and 3 tie, 1 and 4 tie
12
330( boldsymbol{R} ) that carries a charge uniformly
distributed throughout its volume. The
volume charge density is ( rho . ) A Gaussian
sphere of radius ( a ) is imagined that is
concentric to the charged sphere.

If ( a>R, ) what is the charge enclosed in
the Gaussian surface?
( mathbf{A} cdot Q_{e n c}=4 pi rho R^{2} )
( ^{mathbf{B}} Q_{e n c}=frac{4}{3} pi rho a^{3} )
( mathbf{c} cdot Q_{e n c}=4 pi rho a^{2} )
( mathrm{D} )
( E cdot Q_{e n c}=pi rho a^{2} )

12
331For the electrostatic charge system as
shown in Fig. 3.121 , find
a. The net force on electric dipole, and
b. Electrostatic energy of the system
12
332All free electric charges can be
( (e=operatorname{single} ) unit of charge i.e. the
magnitude of charge on electron
This question has multiple correct options
A. odd multiples of ( e )
B. fractional multiples of ( e )
c. even multiples of ( e )
D. negative multiples of ( e )
12
333A 10 pF parallel plate capacitor is charged with a ( 4.0 mathrm{V} ) battery. While the capacitor is still connected to the battery, a dielectric slab ( ( k=5.0 ) ) is inserted between the plates to
completely fill the gap. How much electric potential energy is stored in the capacitor after inserting the dielectric?
begin{tabular}{l}
A ( .5 .3 times 10^{-10} J ) \
hline
end{tabular}
В . ( 4.0 times 10^{-10} mathrm{J} )
c. ( 4.6 times 10^{-10} J )
D. ( 5.6 times 10^{-10} mathrm{J} )
12
334Charge density is a measure of electric charge per unit volume of
space,
A. in one dimension
B. in two dimensions
c. in three dimensions
D. All of the above
12
335( A ) and ( B ) are two hollow metal spheres
of radii ( 50 c m ) and ( 1 m ) carrying charges
( 0.6 mu C ) and ( 1 mu C ) respectively. They are connected externally by a conducting wire. Now the charge flows from :
A. ( A ) to ( B ) till the charges become equal
B. ( A ) to ( B ) till the potentials become equal
c. ( B ) to ( A ) till the charges become equal
D. ( B ) to ( A ) till the potentials become equal
12
336topp ( E )
( Q ) туре уоиг question
3
12
337彥光 ( (infty) )
( frac{x+14}{x+1} )
( frac{x}{10} )
12
338An infinitely large thin plane sheet has
a uniform surface charge density ( +sigma ) Obtain the expression for the amount of work done in bringing a point charge ( q ) from infinity to a point, distant ( r, ) in front of the charged plane sheet.
12
339The mass of proton is 1836 times that of an electron. An electron and a proton are
projected into a uniform electric field in a direction perpendicular to the field with equal initial kinetic energies, then:
A. the electron trajectory is less curved than the proton trajectory
B. the proton trajectory is less curved than the electron trajectory
c. both trajectories are equally curved
D. both trajectories will be straight
12
340The electric field for ( boldsymbol{R}_{1}<boldsymbol{r}<boldsymbol{R}_{2} ) is
( operatorname{given} operatorname{by} boldsymbol{E}=frac{Q}{boldsymbol{X} boldsymbol{pi} varepsilon_{0} r^{2}}left[frac{r^{3}-boldsymbol{R}_{1}^{3}}{R_{2}^{3}-boldsymbol{R}_{1}^{3}}right] . ) Find ( mathbf{X} ? )
12
341Mark out the correct options.
A. The total charge of the universe is constant
B. The total positive charge of the universe is constant.
C. The total negative charge of the universe is constant
D. The total number of charged particles in the universe is constant
12
342Three charged particles are in equilibrium under their electrostatic forces only:
This question has multiple correct options
A. The particles must be collinear
B. All the charges cannot have the same magnitude
c. All the charges cannot have the same sign
D. The equilibrium is unstable
12
343Which of the following statements is
not true about electric field lines?
A. Electric field lines start from positive charge and end at negative charge
B. Two electric field lines can never cross each other
C. Electrostatic field lines do not form any closed loops
D. Electric field lines cannot be taken as continuous
curve
12
344mass ( m ) is hanging in front of a large non-conducting sheet having surface charge density ( sigma ). If suddenly a charge ( +q ) is given to the bob ( & ) it is released
from the position shown in figure. The maximum angle through which the string is deflected from vertical is ( x tan ^{-1}left(frac{sigma q_{0}}{2 varepsilon_{0} m g}right) . ) Find ( x )
12
345is the electrical charges generated by rubbing.
A. electricity
B. static charge
( c . ) both a and ( b )
D. none of the above
12
346and ( C ) have radii ( a, b ) and ( c(a<b<c) )
and surface charge densities on them
( operatorname{are} sigma,-sigma, ) and ( sigma ) respectively. The
values of ( boldsymbol{V}_{boldsymbol{A}} ) and ( boldsymbol{V}_{boldsymbol{B}} ) will be:
A ( cdot frac{sigma}{epsilon_{0}}(a-b+c), frac{sigma}{epsilon_{0}}left(frac{a^{2}}{b}-b+cright) )
B ( cdot frac{sigma}{epsilon_{0}}(a-b+c), frac{sigma}{epsilon_{0}} frac{a^{2}}{c} )
c. ( frac{sigma}{epsilon_{0}}(a+b-c), frac{sigma}{epsilon_{0}}left(frac{a^{2}}{c}-b+cright) )
( stackrel{sigma}{epsilon_{0}}left(frac{a^{2}}{c}-frac{b^{2}}{c}+cright), frac{sigma}{epsilon_{0}}(a-b+c) )
12
347A small metal sphere carrying charge
( +Q ) is located at the centre of a spherical cavity in a large uncharged metallic
spherical shell. Write the charges on the
inner and outer surfaces of the shell.
Write the expression for the electric
field at the point ( P_{1} ) is ( E=frac{x Q}{4 pi epsilon_{0} r_{1}^{2}} . ) Then
the value of ( x ) is :
12
348A electric dipole having charge ( q ) and
( -q ) are placed at distance ( ^{prime} d^{prime} ) is in
equilibrium in a uniform electric filed ( boldsymbol{E} )
Each charge has mass ‘ ( m^{prime} . ) If dipole is displayed by small angle. Then its angular frequency of oscillation is:
A ( cdot sqrt{frac{3 q E}{m d}} )
в. ( sqrt{frac{q E}{2 m d}} )
c. ( sqrt{frac{2 q E}{m d}} )
D. ( sqrt{frac{2 q E}{3 m d}} )
12
349A uniformly charged non-conducting thin hemispherical shall is shown in
figure. What is correct direction of net
electric field at any point on its open
plane surface?
( A )
B. 2
( c cdot 3 )
D. 4
12
350A point charge ( q ) is situated at a
distance ( r ) on axis from one end of a
thin conducting rod of length ( L ) having a
charge ( Q ) (Uniformly distributed along its length). The magnitude electric force between the two is
A ( cdot frac{k q^{2}}{r(r+L)} )
в. ( frac{K Q q}{r^{2}} )
c. ( frac{K Q q}{r(r-L)} )
D. ( frac{K Q q}{r(r+L)} )
12
351The flux passing through the surface ( S_{5} )
will be
( mathbf{A} cdot-0.135 N m^{2} C^{-} )
B. ( -0.054 N m^{2} C^{-1} )
( c cdot 0.081 N m^{2} C^{-1} )
) ( 0.054 N m^{2} C^{-1} )
12
352Determine ( V ) for ( r<R )
A ( cdot frac{rho}{6 epsilon_{0}}left(3 R^{2}right) )
В. ( frac{rho}{6 epsilon_{0}}left(r^{2}right) )
c. ( frac{rho}{6 epsilon_{0}}left(3 R^{2}-r^{2}right. )
D. ( frac{rho}{6 epsilon_{0}}left(3 R^{2}+r^{2}right) )
12
353Which of the following is an insulator?
A. woodd
B. Iron
c. carbon
D. Silver
12
354A charged oil drop is suspended in 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 ( =mathbf{9 . 9} times mathbf{1 0}^{-mathbf{1 5}} ) and ( boldsymbol{g}=mathbf{1 0} )
A . ( 3.3 times 10^{-18} mathrm{C} )
B . ( 3.2 times 10^{-18} mathrm{C} )
c. ( 1.6 times 10^{-18} mathrm{C} )
D. ( 4.8 times 10^{-18} mathrm{C} )
12
355A charge q is accelerated through a potential difference V. It is then passed normally through a uniform magnetic field, where it moves in a circle of
radius r. The potential difference required to move it in a circle of radius
( 2 r ) is?
A . 2 v
B. 4 v
c. ( 1 v )
D. 3
12
356State whether true or false.
A jute string can be used to make a circuit instead of metal wires,
A. True
B. False
12
357Two metal plates having a potential difference of ( 800 mathrm{V} ) are ( 2 mathrm{cm} ) apart. It is
found that a particle of mass ( 1.96 times ) ( 10^{-15} K g ) remain suspended in the
region between the plates. The charge on the particle must be:
( A cdot 3 e )
B. ( 4 e )
( c cdot 6 e )
D. ( 8 e )
12
358A solid conducting sphere having a charge ( Q ) is surrounded by an uncharged concentric conducting hollow spherical
shell. Let the potential difference between the surface of the solid sphere and that of the outer surface of the hollow shell be
( V . ) If the shell is now given a charge of ( 3 Q )
the new potential difference between the same two surfaces is :
A. ( V )
B. 2 ( V )
( c cdot 4 v )
D. ( -2 V )
12
359Find the magnitude of a charge which produces an electric field of strenght is
( 18 times 10^{3} N C^{-1} ) at a distance of ( 5 mathrm{m} ) in
air.
A. ( 50 mu c )
B. ( 100 mu c )
( c cdot 25 mu c )
D. 250 muc
12
360uniformly distributed charge ( Q ). The rod
has been bent in a ( 120^{circ} ) circular arc of
radius ( r . ) In terms of ( Q ) and ( r, ) what is
the electric field ( vec{E} ) due to the rod at
point ( boldsymbol{P} ? )
A ( quad vec{E}=frac{3 sqrt{3} lambda}{8 pi^{2} epsilon_{0} r^{2}} hat{i} ) where ( lambda=frac{2 Q}{3 pi r} )
B ( quad vec{E}=frac{3 sqrt{3} lambda}{8 pi^{2} epsilon_{0} r^{2}} hat{i} ) where ( lambda=frac{3 Q}{2 pi r} )
C ( quad vec{E}=frac{3 sqrt{3} lambda}{8 pi^{2} epsilon_{0} r^{2}} hat{j} ) where ( lambda=frac{2 Q}{3 pi r} )
D ( quad vec{E}=frac{3 sqrt{3} lambda}{8 pi^{2} epsilon_{0} r^{2}} hat{j} ) where ( lambda=frac{3 Q}{2 pi r} )
12
361Two bodies are changed by rubbing one
against the other. During the process,
one becomes positively charged while
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.
12
362If two bodies ( A ) and ( B ) (A bigger in size than ( mathrm{B} ) ) are rubbed together, then :
A. A and B get equal and opposite charges
B. A and B get equal and similar charges
c. A gets more charge than B, but of opposite kind
D. A gets less charge than B, but of same kind
12
363In free space, a particle A of charge ( 1 mu C ) is held fixed at a point P. Another particle B of the same charge and mass ( 4 mu g ) is kept at a distance of 1 mm from
P. if ( mathrm{B} ) is released, then its velocity at a distance of ( 9 mathrm{mm} ) from ( mathrm{P} ) is :
( left[text { Take } frac{1}{4 pi varepsilon_{0}}=9 times 10^{9} N m^{2} C^{-2}right] )
A ( .2 .0 times 10^{3} mathrm{m} / mathrm{s} )
в. ( 3.0 times 10^{4} mathrm{m} / mathrm{s} )
c. ( 1.5 times 10^{2} m / s )
D. ( 1.0 m / s )
12
364‘The charge on a body cannot be
( mathbf{A} cdot e )
B.
c. ( 1.5 e )
D. all the above
12
365A plane area of ( 100 mathrm{cm}^{2} ) is placed in uniform electric field of ( 100 N / C ) such that the angle between area vector and
electric field is ( 60^{circ} . ) The electric flux
over the surface is
A . ( 0.5 mathrm{wb} )
B. ( 5 mathrm{Wb} )
( c cdot 1 w b )
D.
12
366Materials which allow larger currents to flow through them are called:
A. insulators
B. conductors
c. semiconductors
D. alloys
12
367Calculate the electric field intensity required to just support a water drop let
of mass ( 10^{-7} k g ) and having a charge of ( +4.0 times 10^{-13} C )
12
368An electric dipole of moment ‘p’ is placed in an electric field of intensity ‘E’. The dipole acquires a position such that the axis of the dipole makes an angle 0 with the direction of the field. Assuming that the potential energy of the dipole to be zero when ( theta=90^{0} ), the torque and
the potential energy of the dipole will respectively be:
A. ( p E sin theta, 2 p E cos theta )
B. ( p E cos theta,-p E sin theta )
c. ( p E sin theta,-p E cos theta )
D. ( p E sin theta,-2 p E cos theta )
12
369The number of electric field lines
( operatorname{crossing} ) an area ( Delta S ) is ( n_{1} ) when ( Delta vec{S} | vec{E}_{1} )
while the number of field lines
crossing the same area is ( n_{2} ) when ( Delta overrightarrow{boldsymbol{S}} ) makes an angle of ( 30^{circ} ) with ( vec{E} ). Then
A ( cdot n_{1}=n_{2} )
в. ( n_{1}>n_{2} )
c. ( n_{1}<n_{2} )
D. cannot say anything
12
370Coulomb’s law relates two charges and
distance between them describing the electric force as being:
A. proportional to the sum of the charges
B. inversely proportional to the distance between charges
C. proportional to the product of the charges and inversely proportional to the distance
D. proportional to the product of the charges and inversely proportional to the square of the distance
12
371Use Gauss’s law to show that due to a
uniformly charged spherical shell of radius ( mathrm{R} ), the electric field at any point
situated outside the shell at a distance
r from its centre is equal to the electric field at the same point, when the entire charge on the shell were concentrated
at its centre. Also plot the graph showing the variation of electric field
with ( r, ) for ( r leq R ) and ( r geq R )
12
372Figure shows tracks of three charged particles in a uniform electrostatic field. Give the signs of the three charges.Which particle has the highest charge to mass ratio?12
373Three charges ( 4 q, Q ) and ( q ) are in straight line in the position o, ( 1 / 2 ) and I respectively the resultant force on q will be
A.
B.
( c cdot-1 )
D. 0.5
12
374An ebonite rod rubbed with fur and a
glass rod rubbed with silk cloth are brought nearer to each other. Then :
A. They will attract each other
B. They will repel each other
C. Nothing will happen to them
D. They will get heated up
12
375When we touch a steel rod and a paper
simultaneously, we feel that the rod is
colder because:
A. iron being a good conductor conducts more heat from our body
B. paper being a good conductor conducts more heat from our body
C. more heat flows from the iron to our body
D. more heat flows from the paper to our body
12
376A small conducting sphere of radius ( a )
carrying a charge ( +Q, ) is placed inside
an equal and oppositely charged conducting shell of radius ( b )
such that their centers coincide.
Determine the potential at a point
which is at a distance ( c ) from center
such that ( a<c<b )
A. ( k(Q / c+Q / b) )
в. ( k(Q / a+Q / b) )
c. ( k(Q / a-Q / b) )
D. ( k(Q / c-Q / b) )
12
377An electric dipole ( pm 4 mu C ) is kept at coordinate points (1,0,4) are kept at ( (2,-1,5), ) the electric field is given by ( vec{E}=20 hat{i} N C^{-1} . ) Calculate the torque on
the dipole.
12
37811
the highest charge?
( mathbf{A} )
( B )
( mathbf{C} )
D. Cannot be ascertained
12
379The existence of a negative charge on a body implies that it has:
A. lost some of its electrons
B. lost some of its atoms
c. acquired some electrons from outside
D. acquired some protons from outside
12
380Select the odd one out w.r.t. conduction
of heat (wood, paper, plastic, silver)
A . silver
B. woodd
c. paper
D. plastic
12
381The nucleus of helium atom contains
two protons that are separated by distance ( 3.0 times 10^{-15} ) m. The magnitude
of the electrostatic force that each
proton exerts on the other is:
A . ( 20.6 N )
B. 25.6 N
c. ( 15.6 N )
D. ( 12.6 N )
12
382A hollow metal sphere of radius ( R ) is
charged with a charge ( Q . ) The electric potential and intensity inside the sphere are respectively:
A ( cdot frac{Q}{4 pi epsilon_{0} R^{2}} ) and ( frac{Q}{4 pi epsilon_{0} R} )
B. ( frac{Q}{4 pi epsilon_{0} R} ) and zero
c. zero and sero
D. ( frac{4 pi epsilon_{0} Q}{R} ) and ( frac{Q}{4 pi epsilon_{0} R^{2}} )
12
383A positive charge q is placed in a spherical cavity made in a positively charged sphere. The centres of sphere and cavity are displaced by a small distance ( vec{l} ). Force on charge q is :
A . in the direction parallel to vector ( vec{l} )
c. in a direction which depends on the magnitude of charge density in sphere
D. direction can not be determined
12
384When an electron and a proton are
placed in an electric field
A. The electric forces acting on them are equal in magnitude as well as direction
B. Only the magnitudes of forces are same
C. Accelerations produced in them are same
D. Magnitudes of accelerations produced in them are same
12
385A short electric dipole (which consists
of two point charges ( +boldsymbol{q} ) and ( -boldsymbol{q} ) ) is
placed at the centre 0 and inside a
large cube (ABCDEFGH) of length L, as shown in figure. The electric flux,
emanating through the cube is:
( A cdot q / 4 pi varepsilon_{0} L )
B. zero
c. ( q / 2 pi varepsilon_{0} L )
D ( cdot q / 3 pi varepsilon_{0} L )
12
386Paper snippets attracted by a charged
CD is an example of
A. charging by induction
B. charging by conduction
c. charging by ionisation
D. charging by transmission
12
387Two infinite parallel metal planes, contain electric charges with charge densities ( +sigma ) and ( -sigma ) respectively and
they are separated by a small distance
in air. If the permittivity of air is ( epsilon_{0}, ) then
the magnitude of the field between the two planes with its direction will be:
A ( cdot sigma / epsilon_{0} ) towards the positively charge plane
B . ( sigma / epsilon_{0} ) towards the negatively charged plane
C ( cdot sigma /left(2 epsilon_{0}right) ) towards the positively charged plane
D. 0 and towards any direction
12
388Similar charges each other
whereas opposite charges each
other.
A. repel, attract
B. attract, repel
c. repel, repel
D. attract, attract
12
389Coulomb’s law states that the electric
force becomes weaker with increasing distance, Suppose that instead, the
electric force between two charged particles were independent of distance. In this case, would a neutral insulator
still be attracted towards the comb.
12
390Three charges are placed at the vertices
of an equilateral triangle of side a as shown in the figure. The force
experienced by the charge plced at the vertex ( A ) in a direction normal to ( B C ) is :
( A )
( mathbf{B} cdot-Q^{2}left(4 pi varepsilon_{0} a^{2}right) )
c. zero
( ^{mathrm{D}} cdot frac{Q^{2}}{left(2 pi varepsilon_{0} a^{2}right)} )
12
391A rubbed comb can lift paper pieces.
why?
12
392open end of a cylindrical vessel of
radius ( R ) and height ( 2 R ) as shown in figure. the flux of the electric field
through the surface (curved surface ( + )
base ) of the vessel is
( mathbf{A} cdot frac{Q}{varepsilon_{0}} )
B. ( frac{Q}{2 varepsilon_{text {d }}} )
( c cdot frac{Q}{4 varepsilon_{0}} )
D. ( frac{Q}{sqrt{5} varepsilon_{0}} )
12
393( n ) identical charged drops having charge
( q_{0}, ) potential ( V_{0}, ) capacity ( C_{0} ) and energy
( E_{0}, ) coalesce to form a big drop. The new
potential, charge, capacity, energy stored
will be:
B ( cdot frac{2}{n^{3}} V_{0} ; frac{q_{0}}{n_{0}} ; quad n^{frac{1}{3}} C_{0} ; quad n^{frac{3}{5}} U_{0} )
D. ( frac{2}{n^{3}} V_{0} ; frac{q_{0}}{n} ; n^{frac{2}{3}} C_{0} ; n^{frac{5}{3}} U_{0} )
12
394Gauss’s law follows
This question has multiple correct options
A. Coulomb’s law
B. Superposition principle
D. Quantisation principle
12
395An infinite parallel plane sheet of a metal is charged to charge density ( sigma ) coulomb per square metre in a medium of dielectric constant ( K . ) Intensity of electric field near the metallic surface
will be :
( ^{mathrm{A}} cdot_{E}=frac{sigma}{varepsilon_{0} K} )
в. ( _{E}=frac{sigma}{2 varepsilon_{0}} )
( ^{mathrm{c}}=_{E}=frac{sigma}{2 varepsilon_{varepsilon} K} )
D. ( _{E}=frac{K sigma}{2 varepsilon_{0}} )
12
396From below which is the example of insulators.
A. Metallic elements
B. Non Metallic elements
c. graphite
D. acqueous solution of salt
12
397If the charge density at each small drop
be ( sigma, ) then charge density in the larger drop is
A ( cdotleft[4 n^{1 / 3} sigmaright] )
B . ( left[n^{1 / 3} sigmaright] )
c. ( left[3 n^{1 / 3} sigmaright] )
D. ( left[2 n^{1 / 3} sigmaright] )
12
398A hollow dielectric sphere has ( R_{1} ) and
( R_{2} ) as its inner and outer radii. The total
charge carried by the sphere is ( +mathrm{Q} ) which is uniformly distributed throughout the dielectric sphere
between ( R_{1} ) and ( R_{2} ). The electric field
for ( R_{1}<r<R_{2} ) is given by :
( ^{A} cdot frac{Q}{4 pi r in R_{1}} )
в. ( frac{Q}{4 pi epsilon r_{2}} )
c. ( frac{Q}{4 pi in R_{1}^{2}} )
D. ( frac{Qleft(r^{3}-R_{1}^{2}right)}{4 pi in r^{2}left(R_{2}^{3}-R_{1}^{3}right)} )
12
399A molecule of a substance has a
permanent electric dipole moment of magnitude ( 10^{-30} mathrm{cm} . ) A mole of this substance is polarised by applying a strong electrostatic field of magnitude ( 10^{7} mathrm{V} m^{-1} ). the direction of the field is
changed by an angle ( 60 . ) The heat released by the substance In aligning its dipole along the new direction of the
field is:
A . – 6 J
B. -3 J
c. 3
( D .6 )
12
400The maximum Coulomb force that can
act on the electron due to the nucleus in
a hydrogen atom will be:-
A. ( 0.82 times 10^{-8} N )
N ( . . ~ )
В. ( 0.082 times 10^{-8} N )
c. ( 8.2 times 10^{-8} N )
D. ( 820 times 10^{-8} N )
12
401The electronic charge ‘e’ is the possible charge.
A. maximum
B. minimum
c. avarage
D. total
12
402You are provided with a negatively charged gold leaf electroscope. State and explain what happens when an ebonite rod rubbed with fur is brought near the disc of electroscope.
A. divergence increases
B. divergence decreases
c. divergence remains same
D. can’t say
12
403For the given situation irrespective of the magnitude of charge and their
separation it is found that total energy of the system (i.e. electric potential energy and their K.E.) is related to K.E. by the equation total energy = -kinetic energy ( (k) ) Which of the following gives the correct value of potential energy of the system?
A ( cdot frac{q^{2}}{4 pi varepsilon_{0} R} )
В. ( frac{q^{2}}{8 pi varepsilon_{0} R} )
( ^{mathbf{C}}-frac{q^{2}}{4 pi varepsilon_{0} R} )
( ^{mathrm{D}}-frac{q^{2}}{8 pi varepsilon_{0} R} )
12
404Find the net flux through the cylinder.
( mathbf{A} cdot-0.125 N m^{2} / C )
B. ( -0.25 N m^{2} / C )
( mathbf{C} cdot 0.25 N m^{2} / C )
D. ( 0.125 N m^{2} / C )
12
405If the electric field to the left of two
sheets is ( K sigma / varepsilon_{0} . ) Find K?
12
406Two small identical electrical dipoles
( A B ) and ( C D ) each of dipole moment ( vec{p} )
are kept at an angle of ( 120^{circ} ) as shown in
the figure. What is the resultant dipole moment of this combination ? If this
system is subjected to electric field ( (vec{E}) ) directed along ( +boldsymbol{X} ) direction, what will
be the magnitude and direction of the
torque acting on this?
12
407A pyramid has a square base of side ( a ) and four faces which are equilateral triangles. A charge ( Q ) is placed on the centre of the base of the pyramid. What is the net flux of electric field emerging from one of the triangular faces of the
pyramid?
A. 0
в. ( frac{Q}{8 epsilon_{0}} )
c. ( frac{Q a^{2}}{8 epsilon_{0}} )
D. ( frac{Q}{2 epsilon_{0}} )
12
408A thin spherical conducting shell of radius ( mathrm{R} ) has a charge ( mathrm{q} ). Another charge
Q is placed at the centre of the shell. The electrostatic potential at a point ( mathbf{P} ) which is at a distance ( frac{boldsymbol{R}}{mathbf{2}} ) from the centre of the shell is:
( ^{mathbf{A}} cdot frac{2 Q}{4 pi epsilon_{0} R}-frac{2 q}{4 pi epsilon_{0} R} )
В. ( frac{2 Q}{4 pi epsilon_{0} R}+frac{2 q}{4 pi epsilon_{0} R} )
c. ( frac{(q+Q)}{4 pi epsilon_{0} R}+frac{2}{R} )
D. ( frac{2 Q}{4 pi epsilon_{0} R} )
12
409toppr
of the electric filed ( |bar{E}(r)| ) and the
electric potential ( V(r) ) with the
distance ( r ) from the centre, is best
represented by which graph ?
4
3
( c )
( D )
12
410Two identical metallic spheres ( A ) and ( B ) of exactly equal masses are given equal positive and negative charge respectively. Then:
A. mass of ( A> ) Mass of B
B. mass of A <Mass of B
c. mass of ( A= ) Mass of B
D. mass of ( A geq ) Mass of B
12
411Number of electrons constituting ( 1 C )
electric charge is
A ( cdot 6.25 times 10^{18} ) electrons
B. ( 1.6 times 10^{-19} ) electrons
C. ( 6.25 times 10^{-19} ) electrons
D. ( 1.6 times 10^{-18} ) electrons
12
412What is the minimum possible amount of charge?
A. Electronic charge ( e )
B. Electronic charge ( 2 e )
C . Electronic charge ( frac{e}{2} )
D. Electronic charge ( frac{e}{sqrt{2}} )
12
413Find the charge on the inner surface of
the conducting concentric shell
( A cdot Q )
B. ( 2 Q )
( c .-2 Q )
D. ( -Q )
12
414Why is electrical wiring usually made
from copper?
A. Because copper is shiny
B. Because copper conducts electricity
c. Because copper is not magnetic
D. none of these
12
415Suppose the exact charge neutrality does not hold in a world and the electron
has a charge ( 1 % ) less in magnitude
than the proton. Calculate the Coulomb
force acting between two blocks of iron each of mass ( 1 k g ) separated by a distance of 1 m. The number of protons
in an iron atom ( =26 ) and ( 58 k g ) of iron
contains ( 6 times 10^{26} ) atoms.
12
416An electric dipole of momentum ( vec{p} ) is placed in a uniform electric field. The dipole is rotated through a very smal angle from equilibrium and is released. Prove that it executes simple harmonic motion with frequency ( f=frac{1}{2 pi} sqrt{frac{p E}{1}} )
Where, ( I= ) moment of inertia of the
dipole.
12
417A charge ( Q ) is placed at each of two
opposite corners of a square. A charge ( q )
is laced at each of the two opposite corners of the square. If the resultant electric field on ( Q ) is zero, then
( ^{mathbf{A}} cdot Q=-frac{q}{2 sqrt{2}} )
в. ( Q=-2 sqrt{2} q )
c. ( Q=-2 q )
12
418A charged body possesses
A. a positive charge
B. a negative charge
C. either a positive or a negative charge
D. no charge
12
419An electric dipole moment ( vec{P}=(2.0 hat{i}+ ) ( 3.0 hat{j}) mu ) is placed in a uniform electric field ( overrightarrow{boldsymbol{E}}=(mathbf{3 . 0 hat { boldsymbol { i } }}+mathbf{2 . 0 hat { boldsymbol { k } }}) times mathbf{1 0}^{mathbf{5}} mathbf{N} boldsymbol{C}^{-mathbf{1}} )
This question has multiple correct options
A . The torque that ( vec{E} ) exerts on ( mathrm{P} ) is ( (0.6 hat{i}-0.4 hat{j}-0.9 hat{k}) )
( mathrm{Nm} )
B. The potential energy of the dipole is 0.9 J
c. The potential energy of the dipole is 0.6
D. If the dipole is rotated in the electric field, the maximum potential energy of the dipole is 1.3
12
420The intensity of an electric field between the plates of a charged condenser of plate area ( A ) will be :
A ( . A /left(q varepsilon_{0}right) )
в. ( q A / varepsilon_{0} )
c ( cdot q /left(varepsilon_{0} Aright) )
D. none of these
12
421( A ) and ( B ) are two points on the axis and the perpendicular bisector respectively of an electric dipole. ( A ) and ( B ) are far away from the dipole and at equal distance from it. The field at ( A ) and ( B )
( operatorname{are} overrightarrow{boldsymbol{E}}_{boldsymbol{A}} ) and ( overrightarrow{boldsymbol{E}}_{boldsymbol{B}} )
( mathbf{A} cdot vec{E}_{A}=vec{E}_{B} )
B . ( vec{E}_{A}=2 vec{E}_{B} )
c. ( vec{E}_{A}=-2 vec{E}_{B} )
D・ ( left|E_{B}right|=frac{1}{2}left|E_{A}right|, vec{E}_{B} ) is perpendicular to ( vec{E}_{A} )
12
422Easy to shape materials like ceramics are used as
A. conductors
B. insulators
c. electrodes.
D. catalysts.
12
423Which of the following statement is NOT
true?
A. Lightning and spark from woolen clothing are essentially the same phenomena.
B. When you rub a plastic scale on your dry hair, it acquires a charge.
C. Charge acquired by a glass rod when it is rubbed with silk is negative charge.
D. Static charges are called so, because they do not move by themselves.
12
424Inside a neutral metallic spherical shell
a charge ( Q_{1} ) is placed, and outside the
shell, a charge ( Q_{2} ) is placed.
12
electric charges:
A. Two charges exert only electrical force on each other
B. Two charges exert only magnetic forces on each other.
C. Two charges interact electromagnetically.
D. Two charges interact either electrically or magnetically.
12
426What happens when some charge is placed on a soap bubble?
c. The bubble collapses
D. None of the above
12
427( x ) if the potential to which the outer
sphere is raised is ( x times 10^{3} V )
12
428A hollow metallic sphere of radius R is given a charge ( Q ). Then, the potential at the centre is
A. zero
в. ( frac{1}{4 pi epsilon_{0}} cdot frac{Q}{R} )
c. ( frac{1}{4 pi epsilon_{0}} cdot frac{2}{Q} R )
D. ( frac{1}{4 pi epsilon_{0}} cdot frac{Q}{2 R} )
12
429When the metal terminal of a gold-leaf electroscope is touched with a charged
object,
A. the gold leaves spread apart in a “v:
B. the gold leaves close together.
c. the gold leaves remain unaffected.
D. None of these
12
430A Gaussian surface in the figure is
shown by dotted line. The electric field
on the surface will be:
A. due to ( q_{1} ) and ( q_{2} ) only
B. due to ( q_{2} ) only
c. zero
D. due to all
12
431(a) Define electric dipole moment. Is it a
scalar or a vector?
Derive the expression for the electric field of a dipole at a point on the equatorial plane of the dipole.
(b) Draw the equipotential surface due to an electric dipole. Locate the points where the potential due to the dipole is
zero.
12
432Coulomb’s Law is true for
A ( . ) atomic distances ( left(=10^{-11} mathrm{m}right) )
B. nuclear distances ( left(=10^{-15} mathrm{m}right) )
C. charged as well as uncharged particles
D. all the distances
12
433Which one of the following is an insulator?
A. nichrome
B. graphite
c. human body
D. bakelite
12
434Charges ( Q_{1} ) and ( Q_{2} ) lie inside and outside respectively of a closed surface
S. Let ( mathrm{E} ) be the field at any point on ( mathrm{S} ) and
( phi ) be the flux of E over ( S )
This question has multiple correct options
A ( cdot ) If ( Q_{1} ) changes, both ( mathrm{E} ) and ( phi ) will change
B . If ( Q_{2} ) changes, E will change but ( phi ) will not change
C. If ( Q_{1}=0 ) and ( Q_{2} neq 0, ) then ( E neq 0 ) but ( phi=0 )
D. If ( Q_{1} neq 0 ) and ( Q_{2}=0, ) then ( mathrm{E}=0 ) but ( phi neq 0 )
12
435Both gravitational and electric forces
are
A. contact forces
B. central forces
c. attractive forces
D. repulsive forces
12
436Assertion
The effects of charge exchange are usually only noticed when at least one
of the surfaces has a high resistance to
electrical flow.
Reason
This is because the charges that transfer to or from the highly resistive
surface are more or less trapped there for a long enough time for their effects to be observed.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
437Let ( boldsymbol{E}_{a} ) be the electric field due to a
dipole in its axial plane distant ( ell ) and ( boldsymbol{E}_{boldsymbol{q}} ) be the field in the equatorial plane distant ( l^{1}, ) then the relation between ( E_{a} )
and ( boldsymbol{E}_{boldsymbol{q}} ) will be :
( mathbf{A} cdot E_{a}=4 E_{q} )
В . ( E_{q}=2 E_{a} )
( mathbf{c} cdot E_{a}=2 E_{q} )
D. ( E_{q}=3 E_{a} )
12
438The addition of electrons in an atom is
called
A. reduction
B. fusion
c. magnetization
D. None of these
12
439Two equal charges ‘ ( q ) ‘ of opposite sign are separated by a small distance ‘2a’. The electric intensity ‘ ( E ) ‘ at a point on the perpendicular bisector of the line joining the two charges at a very large distance
( ^{prime} r^{prime} ) from the line is :
A ( cdot frac{1}{4 pi varepsilon_{0}} frac{q a}{r^{2}} )
В. ( frac{1}{4 pi varepsilon_{0}} frac{2 q a}{r^{3}} )
c. ( frac{1}{4 pi varepsilon_{0}} frac{2 q a}{r^{2}} )
D. ( frac{1}{4 pi varepsilon_{0}} frac{q a}{r^{3}} )
12
440A circular loop of radius ( 2 mathrm{cm}, ) is placed in a time varing magnetic field with rate of ( 2 mathrm{T} / mathrm{sec} . ) Then induced electric
field in this loop will be
A. 0
B. 0. ( 02 mathrm{V} / mathrm{m} )
( c cdot 0.01 v / m )
D. ( 2 v / m )
12
441The cube as shown in Fig. has sides of
length ( L=10.0 mathrm{cm} . ) The electric field is
uniform, has a magnitude ( boldsymbol{E}=mathbf{4 . 0 0} times )
( 10^{3} N C^{-1}, ) and is parallel to the ( x y- )
plane at an angle of ( 37^{circ} ) measured from
the ( +x-a x i s ) towards the ( +y-a x i s )
Electric flux passing through surface ( boldsymbol{S}_{1} )
is
A ( .-24 N m^{2} C^{-1} )
B. ( 24 N m^{2} C^{-1} )
( mathbf{c} cdot 32 N m^{2} C^{-1} )
D. ( -32 N m^{2} C^{-1} )
12
442Units of electric flux are :
A ( cdot frac{N-m^{2}}{C^{2}} )
в. ( frac{N}{C^{2}-m^{2}} )
c. volt ( -m )
D. volt ( -m^{3} )
12
443Assertion
A charge ( q ) is placed on a height ( h / 4 )
above the centre of a square of side ( b )
The flux associated with the square is independent of side length.
Reason
Gauss’s law is independent of size of the Gaussian surface.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
444The solid angle subtended by the total
surface area of a sphere at the centre is
A . ( 4 pi )
в. ( 2 pi )
( c . pi )
D. ( 3 pi )
12
445Two concentric spherical shells of radii a and 1.2 a have charges ( +mathrm{Q} ) and ( -2 mathrm{Q} ) respectively. At what distance from centre potential will be same as that of centre?
A . 2 a
B. 1.5 a
c. 2.5 a
D. 3a
12
446Assertion
The electric potential due to an electric dipole at a point on the perpendicular bisector of the dipole axis is 0 .
Reason
Any point on the perpendicular bisector of the dipole axis is equidistant from the the two equal and opposite charges.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
447Which of the following statement(s)
is/are correct?
This question has multiple correct options
( mathbf{A} cdot ) If the electric field due to a point charge varies as ( r^{-25} ) instead of ( r^{-2} ), then the Gauss law will still be valid.
B. The Gauss law can be used to calculate the field distribution around an electric dipole.
C. If the electric field between two point charges is zero somewhere, then the sign of the two charges is the same.
D. The work done by the external force in moving a unit positive charge from point ( A ) at potential ( V_{A} ) to point ( B ) at potential ( V_{B} ) is ( left(V_{B}-V_{A}right) )
12
448An electric dipole is along a uniform
electric field. If it is deflected by ( 60^{circ} )
work done by the agent is ( 2 times 10^{-19} J )
Then the work done by an agent if it is
deflected by ( 30^{circ} ) further is:
A ( cdot 2.5 times 10^{-19} mathrm{J} )
В. ( 2 times 10^{-19} J )
c. ( 4 times 10^{-19} mathrm{J} )
D. ( 2 times 10^{-16} J )
12
449A balloon is negatively charged by rubbing and then clings to a wall. Does this mean that the wall is positively
charged ? why does the balloon eventually fall?
12
450Given a uniform electric field ( overrightarrow{boldsymbol{E}}=mathbf{5} times )
( mathbf{1 0}^{3} hat{mathbf{i}} mathbf{N} / mathbf{C}, ) find the flux of this field
through a square of ( 10 mathrm{cm} ) on a side whose plane is parallel to the ( boldsymbol{Y}-boldsymbol{Z} )
plane. What would be the flux through the same square if the plane makes a
( 30^{circ} ) angle with the ( \$ \$ X ) -axis?
12
451Materials that allow electrons to flow
through them are known as
A. Insulator
B. Conductors
c. Electrolytes
D. Bases
12
452A thin insulating ring of radius ( R ) has a
uniform linear charge density ( lambda ). Now a
charge ( Q_{0} ) is placed at centre of this ring. The increment in the stretching
force of the wire due to the charge ( Q_{0} )
is:
A. ( frac{Q_{0} lambda}{2 pi varepsilon_{Omega}} )
в. ( frac{Q_{0} lambda}{4 pi varepsilon_{0} R} )
c. ( frac{3 Q_{0} lambda}{8 pi varepsilon_{0} R} )
D. ( frac{3 Q_{0} lambda}{4 pi varepsilon_{0} R} )
12
453An ebonite rod rubbed with fur and a
glass rod rubbed with silk cloth are brought nearer to each other. Then
A. they will attract each other
B. they will repel each other
C. nothing will happen to them
D. they will get heated up
12
454An isosceles right angle triangle of side d is placed in a horizontal plane. A point charge ( mathrm{q} ) is placed at a distance ( mathrm{d} ) vertically above from one of the corner as shown in the figure. Flux of electric
field passing through the triangle is
A ( cdot frac{q}{36 varepsilon_{0}} )
в. ( frac{q}{18 varepsilon_{0}} )
c. ( frac{q}{24 varepsilon_{0}} )
D. ( frac{q}{48 varepsilon_{0}} )
12
455An oil drop, carrying six electronic
charges and having a mass of ( 1.6 times )
( 10^{-12} g, ) falls with some terminal
velocity in a medium. What magnitude of vertical electric field is required to make the drop move upward with the same speed as it was formerly moving downward with? Ignore buoyancy
A ( cdot 10^{5} N C^{-1} )
B . ( 10^{4} N C^{-1} )
c. ( 3.3 times 10^{4} N C^{-1} )
D. ( 3.3 times 10^{5} N C^{-1} )
12
456Fill in the blank.
Five point charges, each of value ( +boldsymbol{q} boldsymbol{C} ) are placed on five vertices of a regular hexagon of side ( L ) m. The magnitude of the force on the point charge of value ( -q C ) placed at the centre of the
hexagon is ( N )
12
457A neutral water molecule is placed in electic field ( boldsymbol{E}=mathbf{1 . 2 5} times mathbf{1 0}^{mathbf{4}} boldsymbol{N} / boldsymbol{C} . ) The
work done to rotate it by ( 180^{circ} ) is ( 2.5 times )
( 10^{-25} J . ) Find aproximate separation of
center of charges.
A. ( 0.625 times 10^{-9} mathrm{m} )
в. ( 0.65 times 10^{-10} mathrm{m} )
C ( .0 .75 times 10^{-10} mathrm{m} )
D. ( 0.625 times 10^{-10} m )
12
458The diagram shows four charges
( boldsymbol{q}_{1}, boldsymbol{q}_{2}, boldsymbol{q}_{3} ) and ( boldsymbol{q}_{4} ) all lying in the plane of
the page. The diagram also shows the dotted circle that represents the cross-
section of a spherical Gaussian surface
Point ( P ) is a single point on that surface Which of the charges contributes to the net electric flux through the sphere?
A ( cdot q_{1} ) and ( q_{3} )
B. ( q_{2} ) and ( q_{4} )
( mathbf{c} cdot q_{1} ) and ( q_{2} )
( mathbf{D} cdot q_{3} ) and ( q_{4} )
E ( . q_{1}, q_{2}, q_{3}, ) and ( q_{4} )
12
459The electric field outside the plates of
two oppositely charged plane sheets of charge density ( sigma ) is :
A ( cdot+frac{sigma}{2 varepsilon_{0}} )
В. ( -frac{sigma}{2 varepsilon_{0}} )
c. zero
D. ( frac{sigma}{varepsilon_{0}} )
12
460wo lutitical vedus, tach ndve d mass
( m ) and charge ( q . ) When placed in
a hemispherical bowl of radius ( boldsymbol{R} ) with
frictionless, non-conducting walls,
the beads move and at equilibrium they
are at a distance ( R ) apart (as shown in
figure). Determine the charge on each
( ^{mathbf{A}} cdotleft(frac{4 pi varepsilon_{0} m g R^{2}}{sqrt{3}}right)^{1 / 2} )
( ^{mathbf{B}}left(frac{2 pi varepsilon_{0} m g R^{2}}{sqrt{3}}right)^{1 / 2} )
( left(frac{4 pi varepsilon_{0} m g R^{2}}{sqrt{6}}right)^{1 / 2} )
( left(frac{pi varepsilon_{0} m g R^{2}}{sqrt{3}}right)^{1 / 2} )
12
461The amplitude of the electric field in a parallel beam of light of intensity ( 2.0 mathrm{Wm}^{-2} ) is:
A. ( 19.4 mathrm{N} / mathrm{C} )
B. 38.8 N/C
c. ( 4.85 mathrm{N} / mathrm{c} )
D. 77.9 N/C
12
462Who established the fact of animal
electricity?
A. Van de Graaff
B. Count Alessandro Volta
c. Gustav Robert Kirchhoff
D. Hans Christian Oersted
12
463A charge of magnitude ( Q ) is placed at
the origin. A second charge of
magnitude ( 2 Q ) is placed at the position ( boldsymbol{x}=boldsymbol{d} ) along the ( mathbf{x} ) -axis.

Other than infinitely far away, at what position on the ( x ) -axis will a positive test charge experience a zero net force?
A ( x=frac{d}{sqrt{2}} )
B. ( x=frac{d}{2 sqrt{2}} )
c. ( x=frac{d}{3} )
D. ( x=frac{d}{1+sqrt{2}} )
E. At no position other than infinitely far away will the positive test charge experience zero net force

12
464An insulating loop has one side charged positively and the other side charged negatively. An electron is placed in the middle of the loop. What would be the direction of the net force on the electron
due to the charges in the ring?
A. Toward the top of the loop
B. Toward the right of the loop
c. Toward the left of the loop
D. There is no net force on the loop
12
465Two short electric dipoles are placed as
shown. The energy of electric interaction between these dipoles will be:
( mathbf{A} )
B.
( mathbf{c} cdot frac{-2 k P_{1} P_{2} sin theta}{r^{3}} )
D.
12
466Two identical copper spheres carrying charges ( +Q ) and ( -9 Q ) separated by a certain distance has attractive force ( F )
If the spheres are allowed to rouch each
other and moved to distance of
separation ‘x’. So that the force between them becomes ( frac{4 F}{9} ). Then ( X ) is equal to
A. ( d )
B. ( 2 d )
( c cdot d / 2 )
D. ( 4 d )
12
467Gaussian surface measures the electric
field
A. parallel to the surface area
B. tangent to the surface area
c. perpendicular to the surface area
D. anti-parallel to the surface area
12
468Complete the following sentence : A rod is brought near the disc of a positively charged gold leaf electroscope. Ifthe divergence of leaves ( ldots, ) the rod is positively charged; if the divergence of leaves ……… the rod is negatively charged; if the divergence of leaves ( ldots ldots . ) the rod is uncharged.
A. decreases, decreases, decreases
B. increases, decreases, increases.
c. increases, increases, decreases
D. increases, decreases, decreases.
12
469Three point charges ( +boldsymbol{q},-boldsymbol{2} boldsymbol{q} ) and ( +boldsymbol{q} )
are placed at points ( (boldsymbol{x}=mathbf{0}, boldsymbol{y}=boldsymbol{a}, boldsymbol{z}= )
( mathbf{0}),(boldsymbol{x}=mathbf{0}, boldsymbol{y}=mathbf{0}, boldsymbol{z}=mathbf{0}) ) and ( (boldsymbol{x}= )
( boldsymbol{a}, boldsymbol{y}=mathbf{0}, boldsymbol{z}=mathbf{0}) ) respectively. The
magnitude and direction of the electric
dipole moment vector of this charge assembly are :
A . ( sqrt{2 q a} ) along ( +y ) direction
B. ( sqrt{2} q a ) along the line joining points ( (x=0, y=0, z= )
0) and ( (x=a, y=a, z=0) )
c. ( q a ) along the line joining points ( (x=0, y=0, z= )
0) and ( (x=a, y=a, z=0) )
D. ( sqrt{q} a ) along ( +x ) direction
12
470A small sphere of mass ( m ) and having charge ( q ) is suspended by a silk thread of length ( l ) in a uniform horizontal
electric filed. If it stands at a distance ( x )
from the vertical line from point of suspension, then magnitude of electric field is :
A. ( frac{m g}{q} )
в. ( frac{m g}{q} )
c. ( frac{m g x}{q sqrt{l^{2}-x^{2}}} )
D. ( frac{m g l}{q sqrt{x^{2}-l^{2}}} )
12
471Like charges each
other and unlike
charges each other:
A . repel, attract
B. attract, repel
c. repel, repel
D. attract, attract
12
472Coulomb’s Law agrees with
A. Newtons 3rd Law of Motion
B. Newtons 1st Law of Motion
C. Newtons 2 nd Law of Motion
D. All of the above
12
473Six charges are placed at the vertices of
a regular hexagon as shown in the
figure. Find the electric field on the line
passing through ( O ) and perpendicular
to the plane of the figure as a function
of distance ( x ) from point ( O )
A .
B. 4
( c .1 )
D. 2
12
474A spherical capacitor consists of two concentric spherical conductors of
inner one of radius ( R_{1} ) maintained at
potential ( V_{1} ) and the outer one of radius
( boldsymbol{R}_{2} ) at potential ( boldsymbol{V}_{2} . ) The potential at a
point ( p ) at a distance ( x ) from the centre
( left(R_{2}>x>R_{1}right) ) is:
A ( cdot frac{V_{1}-V_{2}}{R_{2}-R_{1}}left(x-R_{1}right) )
B. ( frac{V_{1} R_{1}left(R_{2}-xright)+V_{2} R_{2}left(x-R_{1}right)}{xleft(R_{2}-R_{1}right)} )
C ( cdot V_{1}+frac{V_{2} x}{R_{2}-R_{1}} )
D. ( frac{V_{1}+V_{2}}{R_{2}+R_{1}} x )
12
475toppr ( t )
( mathbf{A} )
B. Diagram B
( c )
D.
( E )
12
476Electric field intensity in free space at a
distance ‘ ( r^{prime} ) outside the charged
conducting sphere of radius ‘ ( boldsymbol{R}^{prime} ) in
terms of surface charge density ‘sigma’ is :
A ( cdot frac{sigma}{epsilon_{0}}left[frac{R}{r}right]^{2} )
В. ( frac{epsilon_{0}}{sigma}left[frac{R}{r}right]^{2} )
c. ( frac{R}{r}left[frac{sigma}{epsilon_{0}}right]^{2} )
D. ( frac{R}{sigma}left[frac{r}{epsilon_{0}}right]^{2} )
12
477The electric field in a certain region is acting radially outward and is given by ( E=A r . A ) charge contained in a sphere
of radius ‘a’ centered at the origin of the
field, will be given by :
A ( cdot 4 pi epsilon_{0} A a^{3} )
В ( cdot epsilon_{0} A a^{3} )
( mathbf{c} cdot 4 pi epsilon_{0} A a^{2} )
D. ( A epsilon_{0} a^{2} )
12
478A charged particle of mass ( 5 times 10^{-6} mathrm{kg} )
is held stationary in space by placing it
in an electric field of strength ( 10^{6} N C^{-1} ) directed vertically downwards. The charge of the particle is ( left(boldsymbol{g}=mathbf{1 0 m} boldsymbol{s}^{-mathbf{2}}right): )
A. ( -20 times 10^{-4} mu C )
B. ( -5 times 10^{-5} mu C )
c. ( 5 times 10^{-11} mu C )
D. ( 20 times 10^{-5} mu C )
12
479For which of the following dependences
of drift velocity ( v_{d} ) on electric field ( mathrm{E} ), is
Ohm’s law obeyed?
A ( cdot v_{d} propto E )
в. ( v_{d} propto E^{2} )
c. ( v_{d} propto sqrt{E} )
D. ( v_{d} propto frac{1}{E} )
12
480The point charges ( -5 n C, 10 n C ) and ( 12 n C ) are located at (0,0,0),(0,0,1) and (0,0,2) respectively. Find the total energy of the system.12
481Work done in turning dipole through an angle 60 is
A. zero
в. ( p E / 4 )
c. ( p E )
D. ( p E / 2 )
12
482A sample of HCl is placed in an electric
field of ( 2.5 times 10^{4} N C^{-1} . ) The dipole
moment of HCl is ( 3.4 times 10^{-30} mathrm{Cm} ). Find
the maximum torque that can act on a
molecule.
A ( cdot 7.6 times 10^{-26} mathrm{Nm} )
В. ( 4.3 times 10^{-26} mathrm{Nm} )
c. ( 6.5 times 10^{-26} mathrm{Nm} )
D. ( 8.5 times 10^{-26} mathrm{Nm} )
12
483Two spheres of equal mass ( A ) and ( B ) are
given ( +q ) and ( -q ) charge respectively then:
A. Mass of A increases.
B. Mass of B increases.
C. Mass of A remains constant.
D. Mass of B decreases.
12
484A thick shell with inner radius ( R ) and
outer radius ( 3 R ) has a uniform charge
density ( sigma c / m^{3} . ) It has a spherical cavity of radius ( R ) as shown in the figure. the
electric field at the centre of the cavity is
A . zero
в. ( 2 sigma R / varepsilon_{0} )
c. ( 3 sigma R / 4 varepsilon_{0} )
D. ( 7 sigma R / 12 varepsilon_{0} )
12
485Electric field inside the cavity of any conductor is
A . Infinite
B ( cdot vec{E}=frac{epsilon_{0}}{sigma} )
c. zero
D・ ( vec{E}=K frac{sigma}{epsilon_{0}} hat{n} )
12
486Four dipoles each one having magnitudes of charges ( pm mathrm{e} ) are placed inside a sphere. The total flux of ( vec{E} ) coming out of the sphere is :
A. zero
в. ( frac{4 e}{varepsilon_{0}} )
( c cdot frac{8 e}{varepsilon_{0}} )
D. None of these
12
487A charge q is situated at the centre of a square of side d. The electric field
intensity at the midpoint of a side is ( mathrm{E}_{1} )
and at one corner of the square is ( mathrm{E}_{2} )
Then, the ratio of ( E_{1} / E_{2} ) is :
A . 0.5
в. 0.7
c. 1
D.
12
488State whether the given statement is
True or False :

Gauss’ law is useful for the calculation
of electrostatic field when the system
doesn’t possess any symmetry.
A. True
B. False

12
489Gold leaf electroscope is used:
A. to measure the electric charge
B. to detect and test small electric charges
C . to produce electric current
D. to produce electric charges
12
490In the given figure distance of the point from A where the electric field is zero is
( mathbf{A} cdot 10 mathrm{cm} )
B. 33 cm
c. ( 20 mathrm{cm} )
D. None of these
12
491112
492A sphere has a charge of ( +50 C . ) The absolute potential at a point at
distance of ( 10^{-12} ) m from the sphere is:
(Radius of the sphere is ( left.<10^{-12} text {m }right) )
A . ( 4500 mathrm{V} )
B . ( 45 times 10^{23} mathrm{V} )
c. ( 4.5 times 10^{23} V )
D. ( 45 times 10^{24} V )
12
493toppr oGın
position ( x=12 mathrm{m} ) on the line.
A proton placed at any point on the line
between the two charges will
experience a net force due to the two
charges. The net force acting on the
proton is shown as a function of
position in the graph, where positive
values of force represent rightward
force.

What is the sign of each charge, and
which charge is stronger?
A. Charge 1 is positive, Charge 2 is positive, and the stronger charge is Charge 2 .
B. Charge 1 is negative, Charge 2 is positive, and the stronger charge is Charge 1
c. Charge 1 is positive, Charge 2 is negative, and the stronger charge is Charge 1.
D. Charge 1 is negative, Charge 2 is positive, and the stronger charge is Charge 2 .
E. Charge 1 is negative, Charge 2 is negative, and the stronger charge is Charge 1.

12
494In a certain region of space, the
potential is given by ( boldsymbol{V}=boldsymbol{k}left[mathbf{2} boldsymbol{x}^{2}-boldsymbol{y}^{2}+boldsymbol{z}^{2}right] . ) The electric field
at the point (1,1,1) has magnitude ( = )
A ( . k sqrt{6} )
в. ( 2 k sqrt{6} )
c. ( 2 sqrt{3} k )
D. ( 4 k sqrt{3} )
is
12
495A very long, solid insulating cylinder
with radius ( R ) has a cylindrical hole
with radius ( a ) bored along its entire
length. The axis of the hole is a distance
( b ) from the axis of the cylinder, where
( a<b<R ) (as shown in figure). The
solid material of the cylinder has a uniform has a uniform volume charge
density ( rho . ) Find the magnitude and
direction of the electric field inside the
hole, and show that this is uniform over
the entire hole.
12
496A point charge of value ( 10^{-7} C ) is
situated at the centre of cube of ( 1 boldsymbol{m} )
side. The electric flux through its total
surface area is:
A. ( 113 times 10^{4} mathrm{Nm}^{2} / mathrm{C} )
в. ( 11.3 times 10^{4} mathrm{Nm}^{2} / mathrm{C} )
C. ( 1.13 times 10^{4} mathrm{Nm}^{2} / mathrm{C} )
D. none of these
12
497Charge is produced by friction
A. Stationary
B. No
c. Attractive
D. All
12
498Electric flux through a surface of area
100 ( m^{2} ) lying in the xy plane is (in ( V ) m) if ( overrightarrow{boldsymbol{E}}=hat{boldsymbol{i}}+sqrt{boldsymbol{2}} hat{boldsymbol{j}}+sqrt{boldsymbol{3}} hat{boldsymbol{k}} )
A. 100
B. 141.4
c. 173.2
D. 200
12
499What are electric lines of force? State
the properties of lines of force.
12
500An electric dipole will experience a net force when it is placed in
A . a uniform electric field
B. a non-uniform electric field
( c . ) both a and ( b )
D. None of these
12
501An electric dipole is placed in an electric field generated by a point charge. Then
A. net electric force on the diploe must be zero
B. net electric force on the diploe may be zero
c. torque on the dipole due to the field must be zero
D. torque on the dipole due to the field may be zero
12
502The Sl unit of electric flux is
A. ( N / C )
в. ( N m / C )
c. ( N m^{2} )
D. ( N m^{2} / C )
12
503State Coulomb’s law in electrostatics.12
504During charging by friction,
A. charge is created.
B. charged is destroyed.
c. charge is conserved.
D. None of these
12
505An electric dipole placed in a non-
uniform electric field experiences:
A. Both a torque and a net force
B. Only a force but no torque
C. Only a torque but no net force
D. No torque and no net force
12
506A positive charge ( q ) at origin is moving with velocity ( v_{0} hat{j} ). Magnetic field at point
( (a,-a) ) is
A. zero
B. ( frac{mu_{0} q v_{0}}{16 sqrt{2} pi a^{2}} hat{k} )
c. ( frac{-mu_{0} q v_{0}}{8 sqrt{2} pi a^{2}} hat{k} )
D. ( frac{-mu_{0} q v_{0}}{4 sqrt{2} pi a^{2}} hat{k} )
12
507Assertion
The positive charge particle is placed in
front of a spherical uncharged conductor. The number of lines of forces
terminating on the sphere will be more than those emerging from it.
Reason
The surface charge density at a point on the sphere nearest to the point charge will be negative and maximum in magnitude compared to other points on the sphere
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason is correct
12
508A point charge ( +Q ) is placed just
outside an imaginary hemispherical
surface of radius ( R ) as shown in the
figure. Which of the following statements
is/are correct?
This question has multiple correct options
A. The electric flux passing through the curved surface of the hemisphere is ( -frac{Q}{2_{varepsilon_{0}}}left(1-frac{1}{sqrt{2}}right) )
B. Total flux through the curved and the flat surface is ( underline{Q} )
C. The component of the electric field normal to the flat surface is constant over the surface
D. The circumference of the flat surface is an
equipotential
12
509A point dipole ( overrightarrow{boldsymbol{p}}=boldsymbol{p}_{0} hat{boldsymbol{x}} ) is kept at the
origin. The potential and electrical field due to this dipole on the y-axis at a distance ( d ) are, respectively:
(Take ( V=0 text { at infinity }) )
A ( cdot frac{|vec{p}|}{4 pi varepsilon_{d} d^{2}}, frac{-vec{p}}{4 pi varepsilon_{0} d^{3}} )
В. ( 0, frac{vec{p}}{4 pi varepsilon_{0} d^{3}} )
c. ( frac{|vec{p}|}{4 pi varepsilon_{0} d^{2}}, frac{vec{p}}{4 pi varepsilon_{0} d^{3}} )
D. ( _{0,} frac{-vec{p}}{4 pi varepsilon_{0} d^{3}} )
12
510What is electric field intensity at any point on the axis of a charged rod of length ‘ ( L ) ‘ and linear charge density’ ( lambda ) ‘?
The point is separated from the nearer end by a.
12
511Suld
and mass ( 1 mathrm{kg} ) are placed (fixed)
central charge of magnitude ( 5 times )
( 10^{-5} C ) and mass 0.5 kg as shown. The
charge at ( P_{1} ) is removed. The
acceleration of the central charge is:
( left[text { Given } boldsymbol{O} boldsymbol{P}_{1}=boldsymbol{O} boldsymbol{P}_{2}=boldsymbol{O} boldsymbol{P}_{3}=boldsymbol{O} boldsymbol{P}_{4}=right. )
( left.O P_{5} 1 m ; frac{1}{4 pi varepsilon_{0}}=9 times 10^{9} text { in SI units }right] )
A ( .9 m s^{-2} ) upwards
B. ( 9 m s^{-2} ) downwards
C ( .4 .5 mathrm{m} mathrm{s}^{-2} ) upwards
D. ( 4.5 m s^{-2} ) downwards
12
512Given a uniform electric field ( overrightarrow{boldsymbol{E}}=mathbf{5} times )
( 10^{3} hat{i} N / C, ) find the flux of this field
through a square of ( 10 mathrm{cm} ) on a side whose plane is parallel to the ( y ) -z plane. What could be the flux through the
same square if the plane makes ( 30^{circ} )
angle with the ( x ) -axis?
12
513When a test charge is brought in from infinity along the perpendicular bisector of an electric dipole, the work done is
A. positive
B. zero
c. Negative
D. None of theses
12
514An electric field ( vec{E}-vec{i} A x ) exists in the
space, where ( A=V / m^{2} ). take the
potential at ( (10 m, 20 m) ) to be zero. Find the potential at the origin.
12
along ( x ) -axis. The equilibrium of a positive test charge placed at the point 0 midway
between them is stable for
displacements along the ( x ) -axis.
Reason: Force on test charge is zero.
A. If both Assertion arid Reason are correct and Reason is the correct explanation of Assertion.
B. If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion,
C. If Assertion is correct but Reason is incorrect.
D. If Assertion is incorrect but Reason is correct
12
516If the potential at each point on a conductor is same to each other, then
A. Electric lines of force may begin or end on the same conductor
B. No electric lines of force may begin or end on the same conductor
c. The electric field inside the conductor may be non-zero
D. None of the above
12
517Three infinitely long charge sheets are
placed as shown in the figure. The
electric field at point ( P ) is going to be
( A )
B. ( -frac{2 sigma}{varepsilon_{0}} )
( c )
D.
12
518An infinite large plate has a net positive charge. When referring to the electric
field just as it is coming out of the
plate:
A. Some of the electric field is perpendicular to the plate
B. All of the electric field is perpendicular to the plate
C. None of the electric field is perpendicular to the plate
D. There is no electric field coming out of the plate
12
519When a glass rod is rubbed with silk
A. Negative charge is produced on silk but not charge on the glass rod
B. Equal but opposite charge are produced on the both
C. Equal and similar charges are produced on the both
D. Positive charge is produced on the glass rod but no charge on the silk
12
520Two electric field lines cannot cross
each other. Also, they cannot form closed loops. Give reasons.
12
521The best conductor of heat is
A. Silver
B. Bronze
c. Aluminium
D. copper
12
522If a body acquires electric charge temporarily under the influence of
charged body, then the process is called:
A. conduction
B. induction
D. dispersion
12
523If ( oint_{s} overrightarrow{boldsymbol{E}} cdot overrightarrow{boldsymbol{d}} boldsymbol{s}=boldsymbol{0} ) over surface, then
A. the electric field inside the surface and on it is zero
B. the electric field inside the surface is necessarily uniform
C . all charges must necessarily be outside the surface
D. all of these
12
524Assertion
Sometime, a crackling sound is heard
while taking off sweater during winters.
Reason
This is due to static electric charges.
A. Both Assertion and Reason are correct and Reason is
the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is
not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
525Uniform electric field of intensity 5 volt/m acts parallel to x axis. A charge of ( 2 C ) is moved from to ( A(1,1), ) to ( B(2,1) )
and finally to ( mathrm{D}(3, mathrm{C}) ) in this field.Work done in this process is :
A. 60 joule
B. 40 joule
c. 30 joule
D. zero
12
526Metals are good conductors because
A. Outer electrons are strongly bound to the atom.
B. Outer electrons are loosely bound to the atom.
C. Inner electrons are loosely bound to the atoms.
D. Protons can detach from the nucleus and conduct
electricity.
12
527Three concentric spherical metallic shells ( A, B ) and ( C ) of radii ( a, b ) and ( c(a<b<c) ) have charge densities
( sigma,-sigma ) and ( sigma ) respectively. If the shells ( A )
and ( C ) are at same potential, then the
relation between ( a, b ) and ( c ) is
A ( . a+b+c=0 )
B . ( a+c=b )
c. ( a+b=c )
D. ( a=b+c )
12
528Figure given below shows three possibilities for the potential at two
points, ( A ) and ( B )
In each case, the same positive charge
is moved from ( A ) to ( B ). The work done in
the positive case will be maximum is:-
begin{tabular}{|cc|cc|cc|}
hline ( mathbf{A} ) & ( mathbf{B} ) & ( mathbf{A} ) & ( mathbf{B} ) & ( mathbf{A} ) & ( mathbf{B} ) \
( mathbf{1 5 0} mathbf{~ V} ) & ( mathbf{5 0} mathbf{~ V} ) & ( mathbf{4 0} ) & ( mathbf{0} ) & ( mathbf{- 4 0} mathbf{V} ) & ( -mathbf{2 0} mathbf{V} ) & ( mathbf{- 8 0} mathbf{~ V} ) \
( mathbf{~ C a s e – 1} ) & & ( mathbf{C a s e -} mathbf{2} ) & & ( mathbf{C a s e}-mathbf{3} ) \
hline
end{tabular}
A. case
B. Case 2
c. case 3
D. In all three cases
12
529A neutral conducting spherical shell is kept near a charge ( q ) as shown. The
potential at point ( P ) due to the induced
charges is :
( A cdot frac{k q}{r} )
в. ( frac{k q}{r^{prime} q} )
с. ( frac{k q}{r}-frac{k q}{r^{prime}} )
D. ( frac{k q}{C P} )
12
530The inside of the bottle of a gold-leaf electroscope is occasionally evacuated
A. to prevent the charge on the terminal from leaking of through ionisation of the air
B. to leak off the charge on the terminal through ionisation of the air
C. to prevent the charge on the terminal from leaking off through induction.
D. None of these
12
531A charge ( Q ) is placed at each of the opposite corners of a sequare. A charge ( q ) is placed at each of the other two
corners. If the net electric force on ( Q ) is
zero, then ( Q / q ) equals:
A . -1
B. 1
c. ( -frac{1}{2} )
D. ( -2 sqrt{2} )
12
532Electric field at a distance ( x ) from the
origin its given as ( boldsymbol{E}=frac{mathbf{1 0 0 N}-boldsymbol{m}^{2} / boldsymbol{C}}{boldsymbol{x}^{2}} )
Then potential difference between the
points situated at ( x=10 m ) and ( x= )
( 20 m ) is:
( A cdot 5 V )
B. ( 10 V )
( c .15 V )
D. ( 4 V )
12
533In general, metals have very low:
A. Boiling Point
B. Freezing Point
c. Melting Point
D. Specific Heat Capacity
12
534A particle of mass ( mathrm{m} ) and charge ( -mathrm{q} ) moves diametrically through a uniformly charged sphere of radius R with total charge ( Q ). The angular frequency of the particle’s simple harmonic motion, if its amplitude ( <mathrm{R} ), is given by :
A. ( sqrt{frac{1}{4 pi varepsilon_{0}} frac{q Q}{m R}} )
в. ( sqrt{frac{1}{4 pi varepsilon_{0}} frac{q Q}{m R^{2}}} )
c. ( sqrt{frac{1}{4 pi varepsilon_{0}} frac{q Q}{m R^{3}}} )
D. ( sqrt{frac{1}{4 pi varepsilon_{0}} frac{m}{m Q}} )
12
535topp
microcoulombs, +2 microcoulombs and
-2 microcoulombs. Find out the
direction of the net electric force acting on the +1 microcoulombs charge.
( A )
B.
( c )
( D )
E
12
536When a glass rod is rubbed with silk,
both become charged due to:
A. migration of protons
B. exchange of electrons and protons
c. migration of electrons
D. migration of neutrons
12
537The electric field for ( r>R_{2} ) is given by
( boldsymbol{E}=frac{1}{boldsymbol{X} boldsymbol{pi} varepsilon_{0}} frac{Q}{r^{2}} . ) Find ( mathbf{X} ? )
12
538A conducting sphere is enclosed by a
hollow conducting shell. Initially the
inner sphere has a charge ( Q ) while the
outer one is uncharged. The potential difference between the two spherical
surface is found to be ( V ). Later on the
outer shell is given a charge ( -4 Q ). The
new potential difference between the
two surface is:
A. ( V )
B. ( -V )
c. ( -2 V )
D. ( 2 V )
12
539A charged gold leaf electroscope has its leaves apart by certain amount having enclosed air. When the electroscope is subjected to X-rays, then the leaves
A. Further dilate
B. Start oscillating
c. collapse
D. Remain unaltered
12
540Charges always reside of the
charged conducting object.
( A ). in the bulk
B. on the surface
c. Both A and B
D. Neither A nor B
12
541A negative point charge ( 2 q ) and ( a )
positive charge ( q ) are fixed at a distance
( l ) apart. Where should a positive test
charge ( Q ) be placed on the line connecting the charge for it to be in equilibrium? What is the nature of the equilibrium with respect to longitudinal
motions?
12
542A suitable unit for expressing the strength of electric field is :
A. v/C
B. ( mathrm{c} / mathrm{m} )
c. N/C
D. c/N
12
543The mutual force of repulsion between two point charges kept a fixed distance
apart is ( 9 times 10^{-5} N ) when in vacuum
and ( 4 times 10^{-5} N ) when placed in a
dielectric medium. What is the value of
dielectric constant of the medium?
12
544toppr
volume. I ne cyıınaer nas a cnarge per
unit length of ( lambda )

A Gaussian surface is imagined that is
also shown in the diagram. This
Gaussian surface is also a cylinder
having the same axis as the charged
is ( a, ) where ( a<R, ) and its length is ( L )
What is the charge enclosed in the
Gaussian cylinder?
( ^{mathbf{A}} cdot Q_{e n c}=lambda frac{a}{R} )
( ^{mathrm{B}} cdot_{e n c}=lambda L frac{a}{R} )
( mathrm{C}_{e n c}=lambda L frac{a^{3}}{R^{3}} )
( mathrm{D} cdot mathrm{Q}_{e n c}=lambda frac{a^{3}}{R^{3}} )
( mathrm{E} cdot Q_{e n c}=lambda L frac{a^{2}}{R^{2}} )

12
545Four equal charges ( Q ) are placed at the
removing a charge ( -Q ) from its centr
A . zero
B. ( frac{sqrt{2} mathrm{Q}^{2}}{4 pi epsilon_{0} mathrm{a}} )
c. ( frac{sqrt{2} mathrm{Q}^{2}}{pi epsilon_{0} mathrm{a}} )
D. ( frac{Q^{2}}{2 pi epsilon_{0} a} )
12
546In Coulomb’s law, the constant of
proportionality K has the units
( N m^{2} / C^{2} ) then the magnitude of ( mathrm{K} ) in air
is :
A ( 9 times 10^{5} )
( ^{5} )
B. ( 9 times 10^{9} )
( mathrm{c} cdot 9 times 10^{3} )
D. none of these
12
547A charge is placed at the edge of a cube
of each side ‘ ( a^{prime} ). Calculate the electric
flux through each face of the cube.
( A cdot frac{Q}{40} )
B. ( frac{Q}{240} )
( c cdot frac{Q}{20} )
D. ( frac{Q}{15 varepsilon_{0}} )
12
548The electric field at a point due to an electric dipole, or an axis inclined at an
angle ( thetaleft(<90^{circ}right) ) to the dipole axis, is perpendicular to the dipole axis, if the angle ( boldsymbol{theta} ) is
A ( cdot tan ^{-1} )
B. ( tan ^{-1}left(frac{1}{2}right) )
( mathbf{c} cdot tan ^{-1}(sqrt{2}) )
D ( cdot tan ^{-1}left(frac{1}{sqrt{2}}right) )
12
549If electric field between plates of a
parallel plate capacitor is ( 2 N C^{-1} ) and
charge on two plates are ( 10 mathrm{C} ) and ( 3 mathrm{C} )
then force on one of the plates is
A. 20 N
B. 30 N
c. ( frac{60}{7} N )
D. ( frac{7}{2} N )
12
550An electric dipole ( dipole moment p) is
placed at a radial distance ( r>>a ) ( Where a
is dipole length) from an infinite line of
charge having linear charge density ( +lambda )
dipole moment vector is aligned along the radial vector ( vec{r} ) force experienced by
the dipole is:-
A ( cdot frac{lambda p}{2 pi varepsilon_{o} r^{2}}, ) attractive
B. ( frac{lambda p}{2 pi varepsilon_{o} r^{3}}, ) attractive
C ( cdot frac{lambda p}{2 pi varepsilon_{o} r^{2}}, ) repulsive
D. ( frac{lambda p}{2 pi varepsilon_{o} r^{3}}, ) repulsive
12
551The dimensional formula for electric
flux density is given by
A ( cdotleft[M L T^{-3} A-1right] )
B . ( left[M L T^{3} A-1right] )
c. ( left[M L T^{-3} A 1right] )
D. ( left[M L T^{3} A 1right] )
12
552Derive an expression for electric
potential at a point due to an electric dipole. Discuss the special cases.
12
553At all points inside a uniform spherical shell –
A. gravitational intensity and gravitational potential both are zero
B. gravitational intensity and gravitational potential both are non- zero
C . gravitational intensity is non- zero and gravitational potential both are zero
D. gravitational intensity is zero and gravitational potential both are non-zero
12
554Two charged particles moving with
velocities ( v_{1} ) and ( v_{2} ) have some
separation between them. The ratio of magnetic force to the Colombian force between them is (c is speed of light)
A. ( frac{v_{1} v_{2}}{c^{2}} )
в. ( frac{c^{2}}{v_{i} v_{2}} )
c. ( frac{c}{v_{1}} )
D. ( frac{c}{v_{2}} )
12
555The total probability of finding a particles in space under normalized condition according to quantum
mechanics is
A. zero
B. Infinity
c. one
D. Uncertain
12
556A charge q is enclosed as shown in all
figure, the electric flux is
(i)
(iii)
A. maximum in (i)
B. maximum in (ii)
c. maximum in (iii)
D. equal in all
12
557In the figure, there are four arcs
carrying positive and negative charges.
All of them have same charge density ( lambda )
Pick incorrect statement(s).
This question has multiple correct options
A. The net dipole moment for the given charge distribution is ( (4 sqrt{5}) lambda R^{2} )
B. The resultant electric field at the center is zero
C. If a uniform ( vec{E} ) is switched on perpendicular to the plane, charge distribution starts rotating about ( X ) -axis
D. Potential at the centre of the given charge distribution
is non-zero
12
558Three charges each of magnitude q are placed at the corners of an equilateral triangle, the electrostatic force on the
charge placed at the center is(each side of triangle is ( L ) )
A. Zero
( ^{mathrm{B}} frac{1}{4 pi varepsilon_{0}} frac{q^{2}}{L^{2}} )
c. ( frac{1}{4 pi varepsilon_{0}} frac{3 q^{2}}{L^{2}} )
( D )
12
559Find the initial acceleration of the rod12
560State Coulomb’s law of force in
electrostatics.
12
561The electric charges are distributed in a small volume. The flux of the electric
field through a spherical surface of
radius ( 10 mathrm{cm} ) surrounding the total charge is ( 20 V ) m. The flux over a
concentric sphere of radius ( 20 mathrm{cm} ) will
be
A ( .20 mathrm{V} . mathrm{m} )
B. ( 25 V . m )
c. ( 40 V . m )
D. 200V.m
12
562Write an expression (derivation not required) for intensity of electric field of an electric dipole, in terms of its length
(2a), dipole moment ( ( p ) ) and distance
( (r) ) for:
(1) Axial position.
12
563How many electron will constitute ( 32 mathrm{C} )
of charge?
A ( .2 times 10^{19} )
B . ( 2 times 10^{18} )
( mathrm{c} cdot 2 times 10^{17} )
D. ( 2 times 10^{20} )
12
564A copper ball of density ( p_{c} ) and diameter
d is immersed in oil of density ( p_{o} . ) What
charge should be present on the ball, so that it could be suspended in the oil, if a homogeneous electric field E is applied vertically upward?
( ^{mathrm{A}} cdot_{mathrm{Q}}=frac{pi d^{2}left(p_{c}-p_{0}right) g}{6 E} )
в. ( quad Q=frac{pi d^{3}left(p_{c}-p_{0}right) g}{6 E} )
c. ( _{Q}=frac{pi d^{3}left(p_{c}-p_{0}right) g}{E} )
D. ( _{Q}=frac{pi d^{2}left(p_{c}-p_{0}right) g}{2 E} )
12
565length ( L, ) pivoted at its centre and
balanced with a weight ( W ) at a distance
( x ) from the left end is shown in the
figure. Two positive point charges
q and ( 2 q ) are attached at the left and
right ends of the rod. A distance ( h )
directly below each of these charges is
a fixed positive charge ( Q ). The distance
( x^{prime} ) in terms of ( q, Q, L ) and ( W ) is
(Assume than ( L>>h ) and neglect
masses of the point charges)
A.
( ^{mathbf{B}} cdot frac{4 q Q L+varepsilon_{0} h^{2} W L}{8 pi h^{2} W} )
( ^{mathbf{C}} cdot frac{q Q L+4 pi varepsilon_{0} h^{2} W L}{8 pi varepsilon_{0} h^{2} W} )
D. ( frac{q Q L+varepsilon_{0} h^{2} W L}{h^{2} W} )
12
566The force experienced on an electric charge of ( 10 mathrm{C} ) placed at a point in the electric field is 50 N. The strength of the electric field at the point is
A ( cdot 25 mathrm{N} mathrm{C}^{-1} )
B. 5 N ( c^{-1} )
c. ( 10 mathrm{N} mathrm{c}^{-1} )
D. 30 N C ( ^{-1} )
12
567How many electrons make up a charge of ( 20 mu C ? )
A ( cdot 1.25 times 10^{14} )
B. ( 2.23 times 10^{14} )
c. ( 3.25 times 10^{14} )
D. ( 5.25 times 10^{14} )
12
568The outermost electrons are
and are called
conduction electrons:
A. not free to move in the atom
B. bound to the protons
c. static
D. able to go to nearby atoms
12
569An electric dipole of moment ( p ) is lying along a uniform electric field ( boldsymbol{E} ). The
work done in rotating the dipole by ( 90^{circ} ) is:
A ( . p E )
B . ( sqrt{2} p E )
c. ( frac{p E}{2} )
D. ( 2 p E )
12
570What is meant by term Quantization of of charge?12
571Two identical particles each of mass ( M )
and charge ( Q ) are placed a certain distance part. If they are in equilibrium under mutual gravitational and electric force then calculate the order of ( frac{Q}{M} ) in
SI units.
12
572An electric dipole is situated in an
electric field of uniform intensity whose dipole moment is p and moment of inertia is I. if the dipole is displaced then the angular frequency of its oscillation is
A ( cdotleft(frac{p E}{I}right)^{1 / 2} )
B. ( left(frac{p E}{I}right)^{3 / 2} )
( ^{mathrm{c}} cdotleft(frac{I}{p E}right)^{1 / 2} )
D. ( left(frac{p}{I E}right)^{1 / 2} )
12
573NaCl molecule is bound due to the
electric force between the sodium and
the chlorine ions when one electron of
sodium is transferred to chlorine.

Taking the separation between the ions to be ( 2.75 times 10^{-8} mathrm{cm}, ) find the force of
attraction between them. State the
assumptions (if any) that you have made.

12
574From below which of them are used in
electrostatic experiments and demonstrations?
A. conductors
B. Insulators
c. Semi conductors
D. None
12
575toppr
rate. In that case, which of the following graphs, drawn schematically, correctly shows the variation of the induced
electric field ( boldsymbol{E}(boldsymbol{r}) ) ?
( A )
B.
( c )
( D )
12
576An electric dipole is placed in a non-
uniform electric field, then
A. The resultant force acting on the dipole is always zero
B. Torque acting on it may be zero
C. The resultant force acting on the dipole may be zero
D. Torque acting on it is always zero
12
577A point charge ( Q ) is placed at the centre
of a circular wire of radius ( boldsymbol{R} ) having
charge q. The force of electrostatic
interaction between point charge and
the wire is:
( A )
в. ( frac{q}{4 pi varepsilon_{R}} )
c. zero
D. none of thes
12
578instrument is used to find the
quantity of electricity of different bodies.
12
579A charged particle initially at rest is kept
in an electric field (choose the most
appropriate option)
A. will always move perpendicular to the line of force.
B. will always move along the line of force in the direction of the field.
C. will always move along the line of force opposite to the direction of the field.
D. will always move along the line of force in the direction of the field or opposite to the direction of the field depending on the nature of the charge.
12
580If the charge ( +Q ) is now at the centre of
a cube of side ( 2 l ), what is the total flux
emerging from all the six faces of the
closed surface?
A ( cdot frac{Q}{epsilon_{0}} )
в. ( frac{Q}{2 epsilon_{0}} )
c. ( frac{Q}{4 epsilon_{0}} )
D. ( frac{Q}{6 epsilon_{0}} )
12
581Across the surface of a charged
conductor,

This question has multiple correct options
A. field is continuous
B. potential is continuous
C. field is discontinuous
D. potential is discontinuous

12
582A rod ( A B ) of mass ( m ) and length ( l ) is positively charged with linear charge density ( lambda mathrm{C} / mathrm{m} ). It is pivoted at end ( mathrm{A} ) and is hanging freely. If a horizontal electric field ( boldsymbol{E} ) is switched on in the region, find the angular acceleration of the rod with
which it starts
A ( cdot frac{E lambda}{2 m} )
в. ( frac{3 E lambda}{2 m} )
c. ( frac{3 E lambda}{m} )
D. zero
12
583The electric field at a point is
A. always continuous
B. continuous if there is no charge at that point
C. discontinuous if there is a charge at that point
D. both
(b) and
(c) are correct
12
584A charged particle of radius ( 5 times 10^{-7} mathrm{m} )
is loacted in a horizontal electric field of
intensity ( 6.28 times 10^{5} V m^{-1} . ) The
surrounding medium has the
coefficient of viscosity ( boldsymbol{eta}=mathbf{1 . 6} times )
( 10^{5} N s m^{-2} . ) The particle starts moving
under the effect of electric field and
finally attains a uniform horizontal speed of ( 0.02 m s^{-1} . ) Find the number of
electrons on it :
(Assume gravity free space)
A . ( 3 times 10^{11} )
в. ( 6 times 10^{1} )
( mathbf{c} cdot 9 times 10^{11} )
D. ( 1 times 10^{11} )
12
585The relation connecting the energy and distance ( r ) between dipole and induced dipole is :
( mathbf{A} cdot U propto r )
B. ( U propto r^{2} )
c. ( U propto r^{-6} )
D. ( U propto r^{6} )
12
586Find the magnitude of the electric field strength as a function of the distance ( r ) both inside and outside the ball12
587A metallic spherical shell has an inner
radius ( boldsymbol{R}_{1} ) and outer radius ( boldsymbol{R}_{2} . ) A charge
is placed at the centre of the spherical cavity. The surface charge density on
the outer surface is
A ( cdot frac{-q}{4 pi R_{1}^{2}} )
В. ( frac{q}{4 pi R_{2}^{2}} )
c. ( frac{q^{2}}{4 pi R_{1}^{2}} )
D. ( frac{2 q}{4 pi R_{2}^{2}} )
12
588What is the charge per unit area in
( C / m^{2}, ) of an infinite plane sheet of
charge if the electric field produced by the sheet of charge has magnitude 3.0 N/C?
12
589A sphere of radius ( mathrm{R} ) has a uniform
volume charge density ( rho . ) The
magnitude of electric field at a distance
from the centre of the sphere, where
( boldsymbol{r}>boldsymbol{R}, ) is?
A ( cdot frac{rho}{4 pi varepsilon_{0} r^{2}} )
B. ( frac{rho R^{2}}{varepsilon_{0} r^{2}} )
C ( cdot frac{rho R^{3}}{varepsilon_{0} r^{2}} )
D ( cdot frac{rho R^{3}}{3 varepsilon_{0} r^{2}} )
E ( cdot frac{rho R^{2}}{4 varepsilon_{0} r^{2}} )
12
590An electric dipole with dipole moment ( overrightarrow{boldsymbol{p}}=(3 i+4 j) times 10^{-30} C-m ) is placed
in an electric field ( overrightarrow{boldsymbol{E}}=mathbf{4 0 0 0 hat { boldsymbol { i } }}(boldsymbol{N} / boldsymbol{C}) )
An external agent turns the dipole and its dipole moment becomes ( (-4 hat{mathbf{i}}+ )
( mathbf{3} hat{boldsymbol{j}}) times mathbf{1 0}^{-mathbf{3 0}} boldsymbol{C}-boldsymbol{m} . ) The work done by
the external agent is equal to:
A ( cdot 4 times 10^{-27} J )
в. ( -4 times 10^{-27} mathrm{J} )
c. ( 2.8 times 10^{-26} J )
D. ( -2.8 times 10^{-26} J )
12
591The most common type of electroscope
is
A. Gold leaf electroscope
B. Elongated electroscope
c. swipe electroscope
D. None
12
592Cause of positive charge on a body is an excess of electrons.
A . True
B. False
12
593When plastic comb is rubbed against dry hair, the plastic comb becomes negative and dry hair becomes positive
A. True
B. False
c. Ambiguous
D. Data insufficient
12
594A charge ( Q ) is distributed over two concentric hollow spheres of radii r and ( R(>r) ) such that the surface charge densities are equal. Find the potential
at the common centre,
A ( cdot frac{Q}{4 pi varepsilon_{0}}left(frac{R-r}{R^{2}+r^{2}}right) )
в. ( frac{Q}{4 pi varepsilon_{0}}left(frac{R+r}{R^{2}+r^{2}}right) )
c. ( frac{Q}{4 pi varepsilon_{0}}left(frac{-R+r}{R^{2}+r^{2}}right) )
D.
12
595( frac{4}{25} ) Coulomb of charge contains
electrons:
( mathbf{A} cdot 10^{15} )
B . ( 10^{18} )
( mathbf{c} cdot 10^{20} )
D. None of these
12
596Find the dimensions of ( G varepsilon_{0} .(G= )
Universal Gravitational constant ( , varepsilon_{0}= )
permittivity in vacuum)
12
597Four point charges ( boldsymbol{q}_{boldsymbol{A}}=boldsymbol{2 mu C}, boldsymbol{q}_{boldsymbol{B}}= )
( -5 mu C, q_{C}=2 mu C, ) and ( q_{D}=-5 mu C )
are located at the corners of a square
( A B C D ) of side ( 10 mathrm{cm} . ) What is the force
on a charge of ( 1 mu C ) placed at the centre
of the square?
12
598A point charge ( Q ) is located on the axis
of a disc of radius ( R ) at a distance ( b )
from the plane of the disc (figure). Show that if one-fourth of the electric flux
from the charge passes through the
disc, then ( R=sqrt{3} b )
12
599Two equal negative charges are fixed at the points ( (0, pm a) ) on the ( y ) -axis. ( A ) positive charge ( Q ) is released from rest at the points ( (2 a, 0) ) on the ( x ) -axis. The
charge ( Q ) will :
A. execute simple harmonic motion about the origin
B. move to the origin ad remain at rest
c. move to infinity
D. execute oscillatory but not simple harmonic motion
12
600An electric charge produces an electric intensity of ( 500 N / C ) at a point in air. If the air is replaced by a medium of dielectric constant ( 2.5, ) then the intensity of the electric field due to the
same charge at the same point will be:
A ( .100 N / C )
в. ( 150 N / C )
c. ( 200 N / C )
D. ( 300 N / C )
12
601A charge ( Q ) is kept at the corner of a cube. Electric flux passing through one of those faces not touches that charge
is:-
( ^{A} cdot frac{Q}{24 epsilon_{0}} )
в. ( frac{Q}{3 epsilon_{0}} )
c. ( frac{Q}{8 epsilon_{0}} )
D. ( frac{Q}{6 epsilon_{0}} )
12
602A coin is dipped in the molten wax in a glass tube. When we heat the upper part of the glass tube, the wax around the coil will not melt because:
A. Wax has a very high melting point
B. Wax is a good conductor of heat
c. Glass is a good conductor of heat
D. Wax or glass are bad conductors
12
603Two charge of ( +25 times 10^{-9} mathrm{C} ) and
( -25 times 10^{-9} mathrm{C} ) are placed ( 6 mathrm{m} ) apart.
Find the electric field intensity ratio at point ( 4 mathrm{m} ) from the centre of the electric dipole
(i) on axial line
(ii) on equatorial line
12
604The figure shows a square loop[ of resistance ( 1 Omega ) side ( 1 m ) being moved
towards right at a constant speed of
1 ( m / s ). The front edge enters the ( 3 m ) wide magnetic field ( (B=1 T) ) at ( t=0 )
draw the graph of current induced in the loop as time passes. (Take the anticlockwise direction of current as
positive)
[
begin{array}{l}
x times x times x times \
x times times times times times \
times times times times times times \
times times times times times times \
times times times times times times
end{array}
]
12
605A thin rod placed long ( x ) -axis from ( x=-a ) to ( x=+a, ) the rod carries a change uniformly distributed along its length with linear charge density ( lambda ). The
potential at the point ( P(2 a, 0,0) ) will be
A ( cdot frac{lambda}{pi epsilon_{0}} operatorname{In} 3 )
в. ( frac{lambda}{4 pi epsilon_{0}} ) In 2
c. ( frac{lambda}{4 pi epsilon_{0}} ) In 3
D. ( frac{lambda}{pi epsilon_{0}} ) In 2
12
606A molecule of a substance has a
permanent electric dipole moment of magnitude ( 10^{-30} mathrm{cm} . ) A mole of this substance is polarised by applying a strong electrostatic field of magnitude ( 10^{7} V m^{-1} . ) The direction of field is
changed by an angle ( 60^{circ} . ) The heat released by the substance in aligning its dipole along the new direction of the field is
A. -6.5
в. ( -3 . )
( c .3 J )
D. 65
12
607Electric charge ( Q, Q ) and ( -2 Q )
respectively are place at the three corner of an equilateral triangle of side
a. Magnitude of the electric dipole moment of the system is:
12
608An electron and a photon each have a
wave length 1 nm. Find the energy pf the photon.
12
609Two identical small equally charged conducting balls are suspended from long threads secured at one point. The charges and masses of the balls are such that they are in equilibrium when the distance between them is a (the
length of thread ( L>> ) a). Then one of the
balls is discharged. What will be the distance ( b(b<<L) ) between the balls when equilibrium is restored?
12
610A charged body is brought near an uncharged gold leaf electroscope. What will be your observation if the body is charged?
A. leaves will diverge
B. leaves will converge
c. leaves will remain unaffected
D. none
12
611Assertion
If a point charge ( q ) is placed in front of an infinite grounded conducting plane surface, the point charge will experience a force.
Reason
This force is due to the induced charge
on the conducting surface which is at zero potential.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
612Two charges of ( -2 Q ) and ( Q ) are located at points ( (a, 0) ) and ( (4 a, 0) ) respectively. What is the electric flux through a sphere of radius ( 3 a ) centred at the
origin?
A ( cdot frac{Q}{epsilon_{0}} )
в. ( frac{-Q}{epsilon_{0}} )
c. ( frac{-2 Q}{epsilon_{0}} )
D. ( frac{3 Q}{epsilon_{0}} )
12
613State whether true or false:
Alcohol and ether are conducting liquids of electricity.
A. True
B. False
12
614An electron at rest has a charge of
( 1.6 times 10^{-19} C . ) It starts moving with a
velocity ( boldsymbol{v}=boldsymbol{c} / 2, ) where ( boldsymbol{c} ) is the speed of
light, then the value the new charge on
it is
( mathbf{A} cdot 1.6 times 10^{-19} ) Coulomb
B. ( _{1.6} times 10^{-19} sqrt{1-left(frac{1}{2}right)^{2}} ) Coulomb
c. ( _{1.6} times 10^{-19} sqrt{left(frac{1}{2}right)^{2}-1 text { Coulomb }} )
( frac{1.6 times 10^{-19}}{sqrt{1-left(frac{1}{2}right)^{2}}} ) Coulom
12
615A large hollow metal sphere of radius has a small opening at the top through which drops of mercury each of radius ( r ) and charged to a potential V fall into the
sphere and the potential becomes ( V^{prime} )
after ( mathrm{N} ) drops fall into it. Then:
A. ( mathrm{V}^{prime}<mathrm{V} ) for any value of ( mathrm{N} )
B. ( mathrm{V}^{prime}=mathrm{V} ) for ( mathrm{N}=1 )
c. ( mathrm{v}^{prime}=mathrm{v} ) for ( mathrm{N}=frac{mathrm{R}}{mathrm{r}} )
D
12
616State the effect on the divergence of the leaves of a gold leaf electroscope on bringing a negatively charged rod near it if the electroscope is positively
charged:
A. Divergence decreases
B. Divergence increases
c. Divergence remains same
D. can’t say
12
617A charge ( Q ) is placed on to two opposite corner of a square. A charge q is placed at each of other two corners. Given that
resultant electric force on ( Q ) is zero,
then ( Q ) is equal to :
A ( cdot(2 sqrt{2}) / q )
B . ( -q /(2 sqrt{2}) )
c. ( (2 sqrt{2}) q )
D. ( (-2 sqrt{2}) q )
12
618A free charge is placed at a point at
which there is no charge, then
A. The charge must be in stable equilibrium
B. The charge may be in stable equilibrium
C. The charge must not be in stable equilibrium
D. The potential energy of the charge is minimum
12
619012
620State whether the given statement is True or False :

When silk is rubbed with glass, the silk gets positively charged.
A. True
B. False

12
621Consider the charges ( boldsymbol{q}, boldsymbol{q} ) and ( -boldsymbol{q} ) placed at the vertices of an equilateral triangle of each side ( l ). The sum of forces
acting on each charge is
A ( cdot frac{q^{2}}{4 sqrt{2} pi varepsilon_{0} l^{2}} )
в. ( frac{-q^{2}}{4 pi varepsilon_{0} l^{2}} )
c. ( frac{q^{2}}{4 pi varepsilon_{0} l^{2}} )
D. zero
12
622Choose the correct statement from the
following
This question has multiple correct options
A. Electric lines of force never cross each other
B. Electric lines of force end at a positive
C. The electric field charge inside a conductor are infinity
D. Lines of electric field point towards regions of lower potential
12
623Positive and negative point charges of equal magnitude are kept at ( left(0,0 frac{a}{2}right) ) and ( left(0,0 frac{-a}{2}right), ) respectively. The work done by the electric field when another
positive point charge is moved from ( (-a, 0,0) ) to ( (0, a, 0) ) is:
A. positive
B. negative
c. zero
D. depends on the path connecting the initial and final positions
12
624what is the net charge on a conducting sphere of radius ( 19 mathrm{cm} ) ? given that the
electric field ( 15 mathrm{cm} ) from the centre of
the sphere is equal to ( 3 times 10^{3} mathrm{N} / mathrm{C} ) and
is directed inward
A. ( -7.5 times 10^{-5} mathrm{C} )
в. ( -7.5 times 10^{-9} mathrm{C} )
c. ( 7.5 times 10^{-5} C )
D. ( 7.5 times 10^{-9} C )
12
625Two identical particles of mass ( m ) carry
charge ( Q ) each. Initially one is at rest on
a smooth horizontal plane and the other
is projected along the plane directly towards the first from a large distance
with an initial speed ( V ). Find the closest
distance of approach.
12
626The density of field lines surrounding any given object reveal information
A. the nature of charge on the source charge.
B. the quantity of charge on the source charge.
c. both A and B
D. it reveals no information
12
627In a certain region of space, electric field is along z-direction throughout The magnitude of electric field is, however, not constant but increases
uniformly along the positive z-direction, at the rate of ( 10^{5} N C^{-1} ) per metre. What
is the torque experienced by a system having a total dipole moment equal to ( 10^{-7} mathrm{C}-mathrm{m} ) in the negative z-direction?
A. 2 N-m
B. 3 N-m
c. ( 4 mathrm{N}-mathrm{m} )
D. zero
12
628Assertion
Work done by the electrostatic field on a charge moving around a closed circular
or elliptical path will be zero.
Reason
Electrostatic field is a conservative
field.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason is correct
12
629Electric field lines of force
A. exist everywhere
B. exist only in the immediate vicinity of electric charges
C. exist only when both positive and negative charges are near one another
D. are imaginary
12
630When electrophorus is charged, the electricity is obtained from :
A. Cat’s skin
B. Metallic plate
c. sole
D. Ebonite plate
12
631Two identical spheres having charges ( 8 mu C ) and ( -4 mu C ) are kept at a certain
distance apart. Now they are brought into contact, after that again they are
kept at the same distance. Compare the forces in the two cases
A . 4: 1
B. 12: 1
c. 8: 1
D. 16: 1
12
632An electric dipole of dipole moment ( vec{p} ) is placed in a uniform electric field ( vec{E} ). The
maximum torque experienced by the dipole is
A ( . p E )
в. ( p / E )
c. ( E / p )
D . ( vec{p} . vec{E} )
12
633Bulbs in street lightning are all connected in
A. parallel
B. series
c. series-parallel
D. end-to-end
12
634On which factors from below does
Coulomb’s law(i.e. law of electrostatic
attraction and repulsion) depends?
A. Magnitude of charges
B. Distance between charges
c. Both magnitude and distance between charges
D. None of the above
12
635Consider a uniform electric field ( boldsymbol{E}= )
( 3 times 10^{3} hat{i} N C^{-1} )
(a) What is the flux of
this field through a square of ( 10 mathrm{cm} ) on a side whose plane is parallel to the yz plane?
(b) What is the flux through the same square if the normal to its plane
makes a ( 60^{circ} ) angle with the ( x ) -axis?
12
636Gauss’s law is true only if force due to a
charge varies as
A ( cdot r^{-1} )
B . ( r^{-2} )
( c cdot r^{-3} )
D. ( r^{-4} )
12
637Three charges ( +4 q, Q ) and ( +q ) are
placed in a straight line with ( Q ) midway
in between the other two charges. If net
force on ( +boldsymbol{q} ) is zero, the charge ( boldsymbol{Q} ) must
be:
A. ( -q )
в. ( -2 q )
c. ( frac{-q}{2} )
D.
12
638The electric potential at a point on the equatorial line of an electric dipole is
A. directly proportional to distance
B. inversely proportional to distance
c. inversely proportional to square of the distance
D. none of the above
12
639A charge ( Q ) is distributed over two
concentric hollow spheres of radii ( r ) and ( R(>r) ) such that the surface densities
are equal. Find the potential at the common centre
12
640A glass rod when rubbed with silk cloth, acquires a charge of ( 1.6 times 10^{-11} C ), then
the charge on silk cloth will be:
A. ( -3.2 times 10^{-11} C )
B . ( -2.4 times 10^{-13} C )
c. ( -1.6 times 10^{-13} C )
D. ( -1.6 times 10^{-11} C )
12
641In the figure shown here, ( A ) is a
conducting sphere and ( mathrm{B} ) is a closed
spherical surface. If a-q change is
placed at ( C ) near ( A ), then the electric flux
through the closed surface is –
A . zero
B. positive
c. negative
D. none of the above can be predicted
12
642Two particles ( X ) and ( Y ), of equal mass
and with unequal positive charges, are free to move and are initially far away
from each other. With ( Y ) at rest, ( X )
begins to move towards it with initial
velocity ( u ). After a long time, finally
A. ( X ) will stop, ( Y ) will move with velocity ( u )
B. ( X ) and ( Y ) will both move with velocities ( u / 2 ) each
c. ( X ) will stop, ( Y ) will move with velocity ( <u )
D. both will move with velocities ( <u / 2 )
12
643Two spheres of radius ( 5 mathrm{cm} ) and ( 10 mathrm{cm} ) both charged to ( 120 mu C ), are joined by a metal wire and then metal wire is
removed. What is the charge on each after removal of the wire?
( mathbf{A} cdot 120 mu C, 120 mu C )
в. ( 80 mu C, 160 mu C )
c. ( 100 mu C, 140 mu C )
D. None of these
12
644A short dipole is placed along the ( x ) -mds at ( x=x text { (Fig. } 3.120) )
a. Find the force acting on the dipole due to a point charge q placed at the origin.
b. Find the force on the dipole if the dipole
is rotated by ( 180^{circ} ) about the z-axis.
c. Find the force on dipole if the dipole is
rotated by ( 90^{circ} ) anticlockwise about z-axis,
i.e., it becomes parallel to the ( y ) -axis.
12
645Which among the following is the best conductor of electricity?
A. Oxygen
B. Aluminium
c. carbon
D. woodd
12
646The process suitable for charging a glass rod is :
A. conduction
B. induction
c. rubbing against a suitable substance
D. all of the above
12
647Two copper spheres, ( A ) and ( B ), are identical in all respect but A carries a charge of ( -3 mu C ) whereas ( B ) Is charged
to ( +1 mu C ). The two spheres are brought together until they touch and then separated by some distance. Which of the following statements is true concerning the electrostatic force ( boldsymbol{F} ) between the spheres?
A. ( F=0 ) as one of the spheres is uncharged
B. ( F=0 ) as both the spheres are uncharged
c. ( F ) is attractive
D. F is repulsive
12
648Two charges equal in magnitude and opposite in polarity are placed at a certain distance apart and effective
force between them is ( F ). If ( 75 % % )
charge of one is transferred to another, then the effective force between the
charges becomes:
A ( cdot frac{F}{16} )
в. ( frac{9 F}{16} )
( c . F )
D. ( frac{15}{16} )
12
649The electric field components due to a
charge inside the cube of side ( 0.1 mathrm{m} ) are
shown in figure.
where, ( boldsymbol{E}_{boldsymbol{x}}=boldsymbol{alpha}, ) where ( boldsymbol{alpha}=500 mathrm{N} / mathrm{C}-mathrm{m} )
( boldsymbol{E}_{boldsymbol{y}}=mathbf{0}, boldsymbol{E}_{boldsymbol{z}}=mathbf{0} )
Calculate
(a) the flux through the cube and
(b) the charge inside the cube.
12
650Three concentric metallic shells ( A, B )
and ( C ) of radii ( a, b ) and ( c(a<b<c) )
have surface charge densities, ( sigma,-sigma )
and ( sigma ) respectively. Find the potentials
of three shells ( A, B ) and ( C ).
12
651Eight point charges (can be assumed
as small spheres uniformly charged
and their centres at the corner of the
cube) having values q each are fixed at
vertices of a cube .The electric flux
through square surface ABCD of the
cube is
A ( cdot frac{q}{24 epsilon_{n}} )
B. ( frac{q}{12 epsilon_{0}} )
c. ( frac{q}{6 epsilon_{0}} )
D. ( frac{q}{8 epsilon_{0}} )
12
652412
653For the circuit shown in figure, the
direction and magnitude of the force on
PQR is:
A . zero
B. ILB out of the page
c. ILB/2 into the page
D. ILB into the page
12
654Three charged particles are in equilibrium under their electrostatic forces only, then:
This question has multiple correct options
A. The particle are collinear
B. All the charges cannot have the same magnitude
c. All the charges cannot have the same sign
D. The equilibrium is unstable
12
655Two charges are placed a certain
distance apart. A metallic sheet is placed between them. What will happen to the force between the charges?
A. Increase
B. Decrease
c. No change
D. either ‘a’ or ‘b
12
656If ( Q_{1}=5 mu C, Q_{2}=3 mu C ) and ( Q_{3}= )
( -2 mu C, ) then the net charge in the
system is :
A. ( -6 mu C )
в. ( 6 mu C )
( c cdot 8 mu C )
D. ( -2 mu C )
12
657An electric dipole placed in a nonuniform electric field may experiences:
A. a force but no torque
B. a torque but no force
c. a force as well as a torque
D. neither a force nor a torque
12
658An electric dipole is held in a uniform electric field
(i) Using diagram show that it does not undergo any translatory motion,
(ii) derive an expression for torque acting on it.
12
659At a certain location, the strength of the electric field is ( 30.0 N / C . ) A charge of ( 3.00 C ) is placed at this location. How much force does this charge
experience due to the electric field?
A. ( 90.0 N )
n
B . ( 10.0 N )
c. ( 0.100 N )
D. ( 270 N / C )
E . ( 3.33 N / C )
12
660Among identical spheres ( A ) and ( B ) having charges as ( -5 C ) and -16 C
A. – -5C is at higher potential
B. -16C is at higher potential
c. Both are at equal potential
D. It cannot be said
12
661An electric dipole is placed in an electric field generated by a point charge.
A. The net electric force on the dipole must be zero
B. The net electric force on the dipole may be zero
c. The torque on the dipole due to the field must be zero.
D. The torque on the dipole due to field may be zero
12
662radii ( 2 R ) and ( 4 R ) respectively are kept at
distances ( x ) and ( 2 x ) from the point
charge ( q . ) A surface cutout of a non
conducting shell ( C ) is kept such that its
centre coincides with the point charge.
Each plate and the spherical surface
carries a surface charge density ( sigma . ) If ( phi_{1} )
is flux through surface of ( (B) ) due to
electric field of ( (A) ) and ( phi_{2} ) be the flux
through ( (A) ) due to electric field of ( (B) )
then:
( mathbf{A} cdot phi_{1}=phi_{2} )
( mathbf{B} cdot phi_{1}>phi_{2} )
( mathbf{c} cdot phi_{1}<phi_{2} )
D. It depend ( R )
12
663The electric field in a region is given by ( overrightarrow{boldsymbol{E}}=frac{mathbf{3}}{mathbf{5}} boldsymbol{E}_{boldsymbol{o}} hat{boldsymbol{i}}+frac{boldsymbol{4}}{mathbf{5}} boldsymbol{E}_{boldsymbol{o}} widehat{boldsymbol{j}} ) with ( boldsymbol{E}_{boldsymbol{o}}=boldsymbol{2} boldsymbol{0} times mathbf{1 0}^{boldsymbol{3}} )
N/C. Find the flux of this field (in
( left.N m^{2} C^{-1}right) ) through a rectangular
surface of area ( 0.2 mathrm{m}^{2} ) parallel to the ( mathrm{Y}-mathrm{Z} )
plane.
12
664When a glass rod is rubbed with silk, it
is said to be positively charged. Which of the following statement is true?
A. Electrons move from silk to glass
B. Electrons move from glass to silk
c. Protons move from silk to glass
D. Protons move from glass to silk
12
665A charge ( +10^{-9} C ) is located at the
origin in free space and another charge
( Q ) at ( (2,0,0) . ) If the ( X ) -component of the electric field at (3,1,1) is zero. The
value of ( Q ) is
A ( cdot 2.4 times 10^{-10} mathrm{C} )
В. ( -6.2 times 10^{-20} C )
c. ( -4.3 times 10^{-10} C )
D. ( -1.2 times 10^{-20} C )
12
666If the number of electric lines of force
emerging out of a closed surface is ( 1000, ) then the charge enclosed by the surface is
A ( cdot 8.854 times 10^{-9} C )
В. ( 8.854 times 10^{-4} C )
c. ( 8.854 times 10^{-1} C )
D. ( 8.854 C )
12
667A cylinder of radius ( R ) and length ( l ) is placed in a uniform electric field ( boldsymbol{E} )
parallel to the axis of the cylinder. The total flux over the curved surface of the
cylinder is :
A. zero
B ( cdot pi R^{2} E )
( mathbf{c} cdot 2 pi R^{2} E )
D. ( E / pi R^{2} )
12
668Two charged conducting spheres of
radii a and b are connected to each
other by a wire. What is the ratio of
electric fields at the surfaces of the two
spheres? Use the result obtained to explain why charge density on the sharp and pointed ends of a conductor is higher than on its flatter portions.
12
669Which of these is a good electrical conductor?
A. water
B. Sweat
c. The human body
D. All of the above
12
670A charged spherical conductor has a
surface charge density of ( 0.07 C / m^{2} )
When its charge is increased by ( 0.44 C ) the charge density changes by 0.14 ( C / m^{2} . ) The radius of the sphere is :
A . ( 5 mathrm{cm} )
в. ( 10 m )
c. ( 0.5 m )
D. ( 5 m )
12
671The potential at a point ( (x, 0,0) ) is given by ( V=left(frac{1000}{x}+frac{1500}{x^{2}}+frac{500}{x^{3}}right) . ) The
intensity of the electric field at ( x=1 )
will be
A. ( 550 V / m )
B. ( 55 V / m )
( mathbf{c} .55000 V / m )
D. ( 5500 V / m )
12
672Electroscope is an instrument used to
find the quantity of charge on different bodies.
A. True
B. False
12
673Electric field due to an infinite sheet of
charge having surface density ( sigma ) is ( E ) Electric field due to an infinite
conducting sheet of same surface density of charge is
A. ( E / 2 )
в. ( E )
( c .2 E )
D. ( 4 E )
12
674In which of the following states is the
potential energy of an electric dipole
maximum?
( A )
B.
( c )
D.
12
675If the electric field in some region of
space is zero,
A. it implies that there is no electric charge in that region.
B. it implies that there is electric charge in that region.
C. it does not imply anything concrete about the charges in the region.
D. it means there is discharging in the region
12
676An electric field is uniform, and in the
positive ( x ) direction for positive ( x, ) and uniform with the same magnitude but
in the negative ( x ) direction for negative
( x . ) It is given that ( boldsymbol{E}=mathbf{2 0 0} hat{boldsymbol{i}} boldsymbol{N} / boldsymbol{C} ) for
( boldsymbol{x}>mathbf{0} ) and ( boldsymbol{E}=-mathbf{2 0 0} hat{boldsymbol{i}} boldsymbol{N} / boldsymbol{C} ) for ( boldsymbol{x}<mathbf{0 . A} )
right circular cylinder of length ( 20 mathrm{cm} )
and radius ( 5 mathrm{cm} ) has its centre at the
origin and its axis along the ( x ) -xis so that one face is at ( x=+10 mathrm{cm} ) and the
other is at ( x=-10 mathrm{cm} )
(a) What is the net outward flux through
each flat face?
(b) What is the flux through the side of the cylinder?
(c) What is the net outward flux through the side of the cylinder?
12
677A particle of mas ( m ) carrying charge ( q ) is released from restm in a uniform
electric field of intensity ( boldsymbol{E} ). The kinetic energy acquired by the particle after moving a distance of ( x ) is (neglect gravitational force):
A ( . q E x )
В ( cdot q E x^{2} )
( mathbf{c} cdot q E^{2} x )
D. ( q^{2} E x )
12
678You are provided with a negatively charged gold leaf electroscope. State and explain what happens when an uncharged metal rod is brought near the disc of electroscope.
A. Divergence increases
B. Divergence decreases
c. Divergence remains same
D. can’t say
12
679Figure shows three point charges
( +2 q,-q a n d+3 q . ) Two charges
( +2 q ) and ( q ) are enclosed within a
surface ( boldsymbol{S} )
What is the electric flux due to this
configuration through the surface ( S ? )
12
680A glass rod when rubbed with silk cloth
acquires a charge ( 1.6 times 10^{-13} C . ) What
is the charge on the silk cloth?
A ( .-1.6 times 10^{-19} C )
В. ( 1.6 times 10^{-13} C )
c. ( -1.6 times 10^{-13} C )
D. ( 1.6 times 10^{-19} C )
12
681Define relative premittivity. Write its
unit.
12
682In a certain region of space,electric field is along the z-direction throughout The magnitude of electric field is however not constant, but increases
uniformly along the positive z-direction at the rate of ( 10^{5} N quad C^{-1} m^{-1} . ) Torque
experienced by the system is:
( mathbf{A} cdot 10^{2} N )
В. ( 10^{-2} N )
c. zero
D. ( 10^{3} N )
12
683A sphere of radius ( r ) is charged to a
potential ( V . ) The outward pull per unit area of its surface is given by:
A ( cdot frac{4 pi epsilon_{0} V^{2}}{r^{2}} )
в. ( frac{epsilon_{0} V^{2}}{r^{2}} )
c. ( frac{2 pi epsilon_{0} V^{2}}{r^{2}} )
D. ( frac{epsilon_{0} V^{2}}{4 r^{2}} )
12
684A very long, straight, then wires carries ( -3.60 n C m^{-1} ) of fixed negative charge. The wire is to be surrounded by a uniform cylinder of positive charge, radius ( 1.50 mathrm{cm} ), coaxial with the wire.
The volume charge density ( rho ) of the cylinder is to be selected so that the net electric field outside the cylinder is zero. Calculate the required positive charge density ( rholeft(operatorname{in} mu C m^{-3}right) )
( A )
в. 7
( c .5 )
( D )
12
685A right circular cone has a semi-vertical angle ( alpha . ) Calculate the solid angle at the
apex P of the cone.
A ( cdot d Omega=2 pi(1-cos alpha) )
в. ( d Omega=2 pi(1-sin alpha) )
c. ( d Omega=2 pi(cos alpha) )
D. ( d Omega=2 pi(sin alpha) )
12
686Two isolated metallic solid sphere of radius ( R ) and ( 2 R ) are charged such that both of these have same charge density
a. the spheres are locted far away from each other and are connected by a thin
conducting wire . the new charge density on the bigger sphere is
A ( cdot frac{5 sigma}{6} )
в. ( frac{56 sigma}{5} )
c. ( frac{3 sigma}{5} )
D. ( frac{52 sigma}{6} )
12
687A solid sphere of radius ( R ) has a charge
( Q ) distributed in its volume with a
charge density ( rho=kappa r^{a}, ) where ( kappa ) and ( a )
are constants and ( r ) is the distance
from its centre.
If the electric field at ( r=frac{R}{8} ) is ( frac{1}{8} ) times
that at ( r=R, ) find the value of ( a )
A . 2.0
B. 3.2
c. 2.5
D. 0.2
12
688Charges ( Q, 2 Q ) and ( 4 Q ) are uniformly distributed in three dielectric solid
spheres 1,2 and 3 of radii ( mathrm{R} / 2, mathrm{R} ) and ( 2 mathrm{R} ) respectively. If magnitudes of the electric fields at point ( P ) at a distance ( R ) from the centre of spheres 1,2 and 3 are
( E_{1}, E_{2}, ) and ( E_{3} ) respectively, then:
A. ( E_{1}>E_{2}>E_{3} )
в. ( E_{3}>E_{1}>E_{2} )
c. ( E_{2}>E_{1}>E_{3} )
D. ( E_{3}>E_{2}>E_{1} )
12
689A hollow conducting sphere is placed in
an electric field produced by a point
charge placed at point ( A, B ) and ( C )
respectively, then:
A. ( V_{C}>V_{B} )
B . ( V_{A}>V_{B} )
с. ( V_{B}>V_{c} )
( mathbf{D} cdot V_{C}=V_{B} )
12
690If there is only one type of charge in the
universe, then what is the flux to the
entire universe.
( (vec{E} rightarrow text { Electric field, } overrightarrow{d s} rightarrow ) Area vector)
( mathbf{A} cdot oint vec{E} cdot overrightarrow{d s} neq 0 ) on any surface
B. ( oint vec{E} cdot overrightarrow{d s} ) could not be defined
( mathbf{c} cdot oint vec{E} cdot overrightarrow{d s}=infty ) if charge is inside
D ( cdot oint vec{E} cdot overrightarrow{d s}=0 ) if charge is outside, ( =frac{q}{epsilon_{0}} ) if charge is
inside
12
positioned al poinis 1 and ( 4, ) ine ( 11 € ) id
intensity to the right of the charge ( Q_{2} )
on the line that passes through the two
charges varies according to a law that is represented schematically in the figure.

The field intensity is assumed to be positive if its direction coincides with
the positive direction on the ( x-a x i s )
The distance between the charges is ( l )
Find the sign of each charge.
A. ( Q_{2} ) is positive and ( Q_{1} ) is negative
B. ( Q_{2} ) is positive and ( Q_{1} ) is positive
( mathrm{C} cdot Q_{2} ) is negative and ( Q_{1} ) is negative
D. ( Q_{2} ) is negative and ( Q_{1} ) is positive

12
692( n ) small drops of same size are charged
to ( V ) volts each. If they coalesce to form a signal large drop, then its potential will be :
A. ( V / n )
в. ( V n )
( mathbf{c} cdot V n^{1 / 3} )
( mathbf{D} cdot V n^{2 / 3} )
12
693Two connected charges of ( +q ) and ( -q )
respectively are at a fixed distance ( boldsymbol{A B} )
apart in a non uniform electric field
whose lines of force are shown in the
figure. The resultant effect on the two
charges is
A. a torque in the plane of the paper and no resultant force
B. a resultant force in the plane of the paper and no torque
c. a torque normal to the plane of the paper and no resultant force
D. a torque normal to the plane of the paper and a resultant force in the plane of the paper
12
694Assertion
A positively charged particle always moves along the electric lines of forces.
Reason
Force on a charged particle is tangential to the electric lines of force.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason is correct
12
695Value of electric potential at the center of uniformly charged non conducting sphere is 30 volt then what will be value of potential at surface.12
696Consider a circle of radius ( R ). A point charge lies at a distance ( a ) from its
center and on its axis such that ( boldsymbol{R}= )
( a sqrt{3} . ) If electric flux passing through the
circle is ( phi, ) find the magnitude of the
point charge.
12
697How much positive and negative charge
is there in a cup of water? Take mass of 1 cup of water as 250 g. Mass of ( 6.02 times 10^{23} ) molecules of water
is 18 g.
12
698A gold leaf electroscope is used
A. Detect the presence of charge on a body
B. Know the nature of charge on a charged body
C. Find the amount of charge present on a charged body
D. Both 1 and 2
12
699Forces between electric charges in relative motion are called:
A. Electromagnetic force
B. Electrostatic force
c. Both a and
D. None of these
12
700The Sl unit of electric flux is
A. Voltmetre
B. Joule/Metre
c. Newton
D. None
12
701A hollow cylinder has a charge ( q ) coulomb within it. If ( f ) the electric flux in
units of volmeter associated with the
curved surface ( mathrm{B} ), the fl乂 linked with the
plane surface A in units of V-m will be:
A ( cdot frac{q}{2 varepsilon_{0}} )
в. ( frac{Phi}{3} )
c. ( frac{q}{varepsilon_{0}} )
D. ( frac{4 q}{varepsilon_{0}} )
12
702What does coulomb’s law of attraction
and repulsion states?
( mathbf{A} cdot F ) is directly proportional to ( q_{1} q_{2} ) and inversely proportional to ( left(r_{12}right)^{2} )
B. F is directly proportional to ( q_{1} q_{2} ) and inversely proportional to ( left(r_{12}right) )
C. ( F ) is indirectly proportional to ( q_{1} q_{2} ) and directly proportional to ( left(r_{12}right)^{2} )
D. None
12
703Three concentric conducting spherical shells of radii ( boldsymbol{R}, 2 boldsymbol{R} ) and ( boldsymbol{3} boldsymbol{R} ) carry
charges ( Q,-2 Q ) and ( 3 Q, ) respectively. Compute the potential at ( r=frac{5}{2} R: )
( A )
В. ( frac{-3 Q}{25 pi varepsilon_{0} R} )
( c )
D.
12
704The electric field in a region of space is given by ( overrightarrow{boldsymbol{E}}=boldsymbol{E}_{0} hat{boldsymbol{i}}+boldsymbol{2} boldsymbol{E}_{boldsymbol{o}} hat{boldsymbol{j}} ) where ( boldsymbol{E}_{boldsymbol{o}}= )
( mathbf{1 0 0} N / C . ) The flux of this field through a
circular surface of radius ( 0.02 mathrm{m} )
parallel to the ( Y ) -Z plane is nearly:
A ( cdot 0.125 mathrm{Nm}^{2} / mathrm{C} )
B . ( 0.02 mathrm{Nm}^{2} / mathrm{C} )
c. ( 0.005 mathrm{Nm}^{2} / mathrm{C} )
D. ( 3.14 mathrm{Nm}^{2} / mathrm{C} )
12
705Ten positively charged particles are
kept fixed on the ( x- ) axis at points ( x= )
( 10 mathrm{cm}, 20 mathrm{cm}, 30 mathrm{cm}, ldots ., 100 mathrm{cm} . ) The
first particle has a charge ( 1.0 times 10^{-8} C )
the second ( 8 times 10^{-8} C, ) the third ( 27 times )
( 10^{-8} C ) and so on. The tenth particle has
a charge ( 1000 times 10^{-8} C . ) Find the
magnitude of the electric force acting on a ( 1 C ) charge placed at the origin.
( mathbf{A} cdot 5.94 times 10^{5} N )
B . ( 5.49 times 10^{5} N )
c. ( 9.45 times 10^{5} N )
D. ( 4.95 times 10^{5} N )
12
706An electric dipole is placed at the centre
of a sphere. Mark the correct option:
This question has multiple correct options
A. the flux of the electric field through the sphere is zero
B. the electric field is zero at every point of the sphere
C. the electric field is not zero anywhere on the sphere
D. the electric field is zero on a circle on the sphere
12
707If coulomb’s law involved ( 1 / r^{3} ) instead
of ( left(1 / r^{2}right), ) would Gauss’s law still be
true?
12
708Objects with the same type of charges attract each other.
A . True
B. False
12
709An insulating sphere with radius a has
a uniform charge density ( rho . ) The sphere
is not centered at the origin but at ( r=b )
Find the electric field at any point inside sphere is ( boldsymbol{E}=frac{boldsymbol{rho}(boldsymbol{x}-boldsymbol{b})}{boldsymbol{n} varepsilon_{0}} . ) what is
the value of ( n )
12
710There are two concentric spherical
shells of radii r and 2r. Initially a charge
( mathrm{Q} ) is given to the inner shell.Now, switch
( S_{1} ) is closed and opened then ( S_{2} ) is
closed and opened and the process is
repeated ( n ) times for both the keys
alternatively. Find the final potential
difference between the shells
12
711An electric field of ( 1000 mathrm{V} / mathrm{m} ) is applied
to an electric dipole at angle of ( 45^{circ} . ) The
value of electric dipole moment is ( 10^{-29} )
C.m. What is the potential energy of the electric dipole?
B. ( -7 times 10^{-27} ) j
( c cdot-10 times 10^{-29} )
D. ( -20 times 10^{-18} mathrm{J} )
12
712If the flux of the electric field through a
closed surface is zero:
A. the electric field must be zero everywhere on the surface
B. the electric field must not be zero everywhere on the surface
C. the charge inside the surface must be zero
D. the charge in the vicinity of the surface must be zero
12
713The work done to rotate the electric dipole
from the equilibrium position by ( 180^{0} ) is :
A. ( 3 times 10^{-23} J )
В. ( 6 times 10^{-23} J )
c. ( 12 times 10^{-23} J )
D. Zero
12
714Three identical positive charges each of value ( Q ) are arranged at the vertices of an equilateral triangle of side length a.
The intensity of the electric field at the
vertex of a regular tetrahedron of which the triangle is the base is:
A ( cdot frac{sqrt{6} k Q}{a^{2}} )
B. ( frac{sqrt{2} text { КQ }}{frac{a^{2}}{2}} )
c. ( frac{sqrt{3} kappa Q}{a^{2}} )
D. None
12
715The normal electric flux per unit area is
called
This question has multiple correct options
A. Electric field intensity
B. Electric force
c. Electric flux density
D. Electric potential
12
716Until when does the charged particle
transmits charge to other?
A. Until the overall repulsive forces between electrons is minimised.
B. Until the overall repulsive forces between electrons is maxmised.
C. Until the overall repulsive forces between electrons is become neutral
D. None
12
717Two similar balls, each of mass ( mathrm{m} ) and
charge ( q, ) are hung from a common point by two silk threads, each of length
I. Prove that separation between the balls is ( boldsymbol{x}=left[frac{boldsymbol{q}^{2} boldsymbol{l}}{2 boldsymbol{pi} varepsilon_{0} boldsymbol{m} boldsymbol{g}}right]^{1 / 3}, ) if ( boldsymbol{theta} ) is small.
Find the rate da/dt with which the charge should leak off each sphere if the velocity of approach varies as ( boldsymbol{v}= ) ( a / sqrt{x}, ) where a is a constant
12
718The flux linked with a circuit is given by
( phi=(t-2)^{2} . ) The graph between
induced emf (y-axis) and time axis ( (x- ) axis) is
A. Straight line through origin
B. Straight line with negative intercept
c. straight line with positive intercept
D. Parabola
12
719An electron, proton, deuteron and ( alpha ) particle enter in a uniform electric field with the same velocity as shown.
The greatest deviation is shown by
A. electron
B. proton
c. deuteron
D. ( alpha ) – particle
12
720Poor conductors of electricity consist of
A . silver
B. aluminum
c. distilled water
D. copper
12
721The conservation of electric charge
implies that
This question has multiple correct options
A. charge cannot be created
B. charge cannot be destroyed
C. the number of charged particles in the universe is constant
D. simultaneous creation of equal and opposite charges is permissible
12
722Find the direction of electric field at
point ( boldsymbol{P} ) for the charge distribution as
shown in the figure.
A. Along positive ( y ) -axis
B. Along negative ( y ) -axis
c. Along positive ( x ) -axis
D. Along negative ( x ) -axis
12
723What will be the effect on the
divergence of the leaves of a uncharged gold leaf electroscope on bringing a negatively charged rod near electroscope?
A. Leaves diverge
B. Leaves converge
c. Leaves remains at same position
D. Can not be determined
12
724A light beam travelling in the ( x ) direction is described by the electric field ( boldsymbol{E}_{boldsymbol{y}}=left(mathbf{3 0 0} boldsymbol{V} boldsymbol{m}^{-1}right) sin quad boldsymbol{omega}(boldsymbol{t}-boldsymbol{x} / boldsymbol{c}) )
An electron is constrained to move
along the y-direction with a speed of ( 2.0 times 10^{7} m^{-1} ) Find the maximum
electric force and the maximum
magnetic force on the electron
A ( cdot 4.8 times 10^{-17} mathrm{N}, ) zero
В. ( 4.2 times 10^{-18} N, 1.8 times 10^{-8} N )
c. ( 4.8 times 10^{-17} N, 3.2 times 10^{-18} N )
D. zero, zero
12
725A line of charge extends along a X-axis whose linear charge density varies
directly as x. Imagine a spherical
volume with its centre located on X-axis
and is moving gradually along it. Which
of the graphs shown in figure
correspond to the flux with the ( x )
coordinate of the centre of the volume
( A )
B.
( c )
( D . d )
12
726When electrons in a material are free to
move, the material is:
A. an insulator
B. a conductor
c. a semiconductor
D. none of these
12
727Which of the following materials is an electrical insulator?
A. Aluminium
B. Gold
c. Rubber
D. all of these
12
728Electric field intensity at a point due to a charge ( Q ) is ( 24 mathrm{N} / mathrm{C} ) and electric potential at ( A^{prime} ) due to charge ( Q ) is ( =12 mathrm{j} / mathrm{C} ) The distance between the charges and magnitude of ( Q ) are
A ( cdot 0.4 m, 0.667 times 10^{-9} mathrm{C} )
B . ( 0.4 m, 6.67 times 10^{-4} mathrm{C} )
c. ( 0.5 m, 2.67 times 10^{-9} mathrm{C} )
D. ( 0.5 m, 7.66 times 10^{-9} mathrm{C} )
12
729Assertion
Gauss’s law show diversion when
inverse square law is not obeyed.
Reason

Gauss’s law is a consequence of
conservation of charges.
A. Both Assertion and Reason are correct and Reason is
the correct explanation for Assertion.
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
C. Assertion is correct but Reason is incorrect.
D. Both Assertion and Reason are incorrect.

12
730A thin spherical conducting shell of radius ( R ) has a charge ( q ). Another charge
( Q ) is placed at the centre of the shell. The electrostatic potential at a point ( mathrm{P} ) at a distance ( boldsymbol{R} / mathbf{2} ) from the centre of the
shell is :
( ^{A} cdot frac{2 Q}{4 pi varepsilon_{Omega} R} )
в. ( frac{2 Q}{4 pi varepsilon_{0} R}-frac{2 q}{4 pi varepsilon_{0} R} )
c. ( frac{2 Q}{4 pi varepsilon_{0} R}+frac{q}{4 pi varepsilon_{0} R} )
D. ( frac{(q+Q) 2}{4 pi varepsilon R R} )
12
731The electric field in the region with
radius ( r, ) where ( c>r>b, ) is
12
732Two point charges of magnitude ( +10^{8} ) coulomb each are placed 0.5 metre in air. At the mid point of line joining then
A. The field is zero, the potential is zero
B. The field is zero, the potential is not zero
c. The field is zero the potential is -720
D. The field is zero the potential is + 720
12
733The surface charge density on a copper
sphere is ( sigma . ) So the intensity of electric field on its surface will be:
A. ( sigma )
B. ( frac{sigma}{2} )
c. ( frac{sigma}{2 varepsilon o} )
D. ( frac{sigma}{varepsilon o} )
12
734Two point charges ( +q ) and ( -2 q ) are kept ( d ) distance apart Find the location of the points on the line joining the two charges at which potential due to this system of charges is zero.12
735Four point charges are fixed in position
at the corners of a square, as shown in above figure
Find out the direction of the total
electrostatic force on the charge in the lower right-hand corner of the square?
A.
B. 4
( c )
( D )
E. The electric force on this charge is
12
736Two particle of equal mass ( m ) and
charge ( q ) are placed at a distance of
16cm. They do not experience any force.
The value of ( frac{boldsymbol{q}}{boldsymbol{m}} ) is :
A. ( sqrt{frac{pi varepsilon_{0}}{G}} )
в. ( L )
c. ( sqrt{frac{G}{pi varepsilon_{0}}} )
D. ( sqrt{4 pi varepsilon_{0} G} )
12
737Find the angular speed of the rod as the
function of angle ( theta ) of rotation ( omega=f(theta) )
if the rod is allowed to rotate freely
12
738An electron moves a distance of ( 6 mathrm{cm} )
when accelerated from rest by an electric field of strength ( 2 times 10^{4} N C^{-1} )
Calculate the time of travel. (mass of
electron ( left.=9.1 times 10^{-31} k gright) )
12
739Define one coulomb charge.12
740The breakdown field for air is about ( 2 x )
( mathbf{1 0}^{6} ) volt/m. Therefore, the maximum
charge that can be placed on a sphere of diameter ( 10 mathrm{cm} ) is
A ( .2 .0 times 10^{-4} mathrm{c} )
В. ( 5.6 times 10^{-7} mathrm{c} )
c. ( 5.6 times 10^{-2} mathrm{c} )
D . ( 2.0 times 10^{2} mathrm{c} )
12
741What causes electrification of two
bodies when they are rubbed together?
A. Transfer of atoms from one body to the other body.
B. Transfer of electricity from one body to the other body.
C. Transfer of electrons from one body to the other body.
D. Transfer of heat from one body to the other body.
12
742A closed surface in the shape of a cube
is placed in a uniform electric field ( boldsymbol{E} )
along one of the sides of the cube as
shown here. The length of the side is ( l )
The total electric flux through two
faces 1 and 2 is:
A . zero
B. ( -E l^{2} )
( c cdot 2 E l^{2} )
D. ( frac{E l^{2}}{2} )
12
charges ( 3 q ) and ( q ) are fixed at the
opposite ends of a horizontal, insulating
rod, extending from the origin to the
point ( boldsymbol{x}=boldsymbol{d} . ) As shown in figure, a third
small charged bead is free to slide on
the rod. At what position is the third
bead in equilibrium? Can it be in stable equilibrium?
A ( cdot frac{sqrt{3} d}{(1+sqrt{3})} ) from ( +3 q ) charge, yes
B. ( frac{sqrt{5} d}{(1+sqrt{3})} ) from ( +3 q ) charge, yes
C ( frac{sqrt{3} d}{(1+sqrt{2})} ) from ( +3 q ) charge, yes
D. ( frac{sqrt{2} d}{(1+sqrt{3})} ) from ( +3 q ) charge, yes
12
744Two point charges placed at a certain distance ( r ) in air exert a force ( F ) on each
other. The distance ( r ) at which these
charges will exert the same force in
medium if dielectric constant k is given by
( A )
в. ( frac{r}{k} )
c. ( frac{r}{sqrt{k}} )
D. none of these
12
745If the electric field is given by ( (5 i+ ) ( 4 j+9 k), ) the electric flux through a
surface of area 20 unit lying in the ( Y-Z ) plane will be :
A. 100 unit
B. 80 unitt
c. 180 unit
D. 20 unit
12
746A charge of ( +2 mu C ) is placed at ( x=0 ) and a charge of ( -32 mu C ) at ( x=60 mathrm{cm} . ) Athird
charge – ( Q ) be placed on the ( x ) -axis such that it experiences no force. The distance of the point from ( +2 mu C ) is (in ( (m) )
( A cdot 30 )
B. 20
c. 15
D. 10
12
747Electric lines of force about a negative
point charge are:
A. Circular anti-clockwise
B. Circular clockwise
12
748Torque acting on an electric dipole in a uniform electric field is maximum if the angle between ( vec{P} ; ) and ( vec{E} ) is:
A ( .180^{circ} )
B . ( 0^{circ} )
( c cdot 90^{circ} )
D. ( 45^{circ} )
12
749Define the following term. Volume charge density.12
750Positive point charges are placed at the
vertices of a star shape as shown in the
figure. Direction of the electrostatic
force on a negative point charge at the
centre ( boldsymbol{O} ) of the star is:
A. Neither along horizontal or vertical direction,
B. Vertically up
C. Towards left
D. Vertically down
12
751An electric dipole moment ( vec{P}=(2.0 hat{i}+3.0 hat{j}) mu C . . m ) is placed in a
uniform electric field ( vec{E}=(3.0 hat{mathrm{i}}+2.0 widehat{k}) times 10^{5} )
A ( cdot ) The torque that ( overrightarrow{mathrm{E}} ) exert on ( overrightarrow{mathrm{P}} ) is ( (0.6 hat{mathrm{f}}+0.4 hat{mathrm{j}}-0.9 widehat{mathrm{k}}) mathrm{Nm} )
B. The potential energy of the dipole is -0.6
c. The potential energy of the dipole is 0.6 .
D. None of these
12
752Electron accelerated by potential ( V ) are
diffracted from a crystal. If ( boldsymbol{d}=mathbf{1} boldsymbol{A} ) and
( boldsymbol{i}=mathbf{3 0}^{circ} . boldsymbol{V} ) should be about ( boldsymbol{h}=mathbf{6 . 6} times )
( mathbf{1 0}^{-mathbf{2 4}} mathbf{J s m}_{e}=mathbf{9 . 1} times mathbf{1 0}^{-mathbf{3 3} mathbf{k g} . boldsymbol{e}}= )
( mathbf{1} . mathbf{6} times mathbf{1 0}^{-mathbf{1 9}} mathbf{C} )
A . ( 2000 V )
в. ( 50 V )
( mathbf{c} .500 V )
D. ( 1000 V )
12
753What is the nature of Gaussian surface
involved in Gauss law of electrostatic?
A. Scalar
B. Electrical
c. Magnetic
D. vector
12
754The equipotential surface of an electric
dipole is:
A. A sphere whose centre coincides with the centre of the electric dipole
B. A plane surface inclined at an angle of ( 45^{circ} ) with the axis of the electric dipole
C. A plane surface passing through the centre of the electric dipole and perpendicular to the axis of the electric dipole
D. Any plane surface parallel to the axis of the electric dipole
12
755Ordinary rubber is an insulator. But the special rubber tyres of aircrafts are made slightly conducting. Why is this
necessary?
A. The charged developed due to atmospheric electricity finds its way to the earth
B. The charged developed due to friction finds its way to the earth
c. The charged developed due to induction finds its way to the earth
D. The charged developed due to the aircraft engine finds its way to the earth
12
756Explain why the electric field inside a conductor placed in an external electric field is zero.12
757When does an electric dipole placed in a uniform electric field experience
a. Maximum Torque
b. Minimum Torque
12
758A charged body is brought near a positively charged gold leaf electroscopes. The divergence of its leaves increases.What is the kind of
charge on the body?
A. Positive
B. Negative
c. Neutral
D. Data insufficient
12
759Generally, good conductors have low specific heat capacity. True/False? Justify your answer.12
760Potential (in V) at ( r=1.25 mathrm{cm} )12
761A thinwalled, spherical conducting shel S of radius ( R ) is given charge ( Q ). The same amountof charge is also placed at its centre C. Which of the following
statements are correct?
This question has multiple correct options
A ( cdot ) on the outer surface of ( mathrm{S} ), the charge density is ( frac{Q}{2 pi R^{2}} )
B. The electric field is zero at all points inside
c. At a point just outside ( S ), the electric field is double the field at a point just inside
D. At any point inside S, the electric field is inversely proportional to the square of its distance from
12
762Two equally charged identical metal spheres ( A ) and ( B ) repel each other with a force F. Another identical uncharged sphere ( C ) is touched to ( A ) and then placed midway between ( A ) and ( B ). The net force on
( mathrm{C} ) is in the direction:
A. ( F ) towards ( A )
B. ( F ) towards
( mathrm{c} .2 F ) towards ( mathrm{A} )
D. ( 2 F ) towards ( B )
12
763Bulb does not glow when the probs are hanged in air. The reason is:
A. air absorbs the electricity
B. air is a bad conductor of electricity
c. electricity is discharged into air
D. air disperses the electricity
12
764The black shapes in the figure are closed surfaces. The electric field lines
are in red. For which case the net flux through the surfaces is non-zero?
(b)
( (c) )
A. In all cases net flux is non-zero
B. Only (c) and (d)
c. only (a) and (b)
D. only (b), (c) and (d)
12
765There is an electric field E in x-direction.
If the work done on moving a charge of ( 0.2 mathrm{C} ) through a distance of ( 2 mathrm{m} ) along a
line making an angle ( 60^{circ} ) with ( x ) -axis is
4 J, then what is the value of E?
A. ( sqrt{3} ) N/C
B. 4 N/C
c. ( 5 mathrm{N} / mathrm{c} )
D. 20 N/C
12
766A charge ( q ) is placed at the centre of the line joining two equal charges ( Q ). The system of three charges will be in equilibrium if ( q ) is equal to:
A ( cdot-frac{Q}{2} )
в. ( -frac{Q}{4} )
( c cdot+frac{Q}{4} )
D. ( +frac{Q}{2} )
12
7671000 small water drops each of radius ( r )
and charge ( q ) coalesce to form one
spherical drop. The potential of big drop is larger than that of smaller ones by a factor
( mathbf{A} cdot 1000 )
B. 100
c. 10
D. 1
12
768The electric flux over a sphere of radius
( 1 m ) is ( phi . ) If radius of the sphere were
doubled without changing the charge
enclosed, electric flux would become
( mathbf{A} cdot 2 phi )
B. ( phi / 2 )
c. ( phi / 4 )
D.
12
769( ln ) a point ( v=-5 x+3 y+sqrt{15} z ) in that point. Find the value of E?12
770A soap bubble of radius ( R ) with wall
thickness ( t ) is charged to a potential ( V_{0} )
The bubble bursts and becomesa
spherical drop of soap solution of
radius ( r . ) Now, it has potential, ( V )
Assume, the soap solution to be a
conductor.

Then the charge carried by the soap
bubble is :

Spherical drop
A ( cdot 4 pi varepsilon_{0} R V_{0} )
В ( cdot 2 pi varepsilon_{0} R V_{0} )
( mathbf{c} cdot 4 pi varepsilon_{0} r V )
D. Both (A) and (C)

12
771Three charges each of value q are placed at the corners of an equilateral triangle. A fourth charge ( Q ) is placed at the center of the triangle.
a. If ( Q=-q, w i | ) the charges at the corners move toward the center or fly away from it
b. For what value of ( Q ) at 0 will the
charges remain stationary?
12
772thin shells of uniformly distributed
positive charge ( Q ) and radius ( d ) are
located a distance ( 10 d ) from each other.
A positive point charge ( q ) is placed
inside one of the shells at a distance
( d / 2 ) from the center, on the line
connecting the centers of the two shells,
as show in the figure. What is the net
force on the charge ( q ? )
A ( cdot frac{Q q}{361 pi varepsilon_{0} d^{2}} ) to the left
B. ( frac{Q q}{361 pi varepsilon_{0} d^{2}} ) to the right
c. ( frac{362 Q q}{361 pi varepsilon_{0} d^{2}} ) to the left
D. ( frac{360 Q q}{361 pi varepsilon_{0} d^{2}} ) to the right
12
773A short electric dipole moment ( vec{p} ) is
placed at a distance ( r ) from the centre
of a solid metallic sphere of radius ( a(< )
( <r) ) as shown in the figure. The
electric field intensity at the centre of
sphere ( C ) due to induced charge on the
sphere is :
A. zero
B. ( frac{1}{4 pi varepsilon_{0}} frac{2 p}{r^{3}} ) along ( C O )
( ^{mathbf{C}} frac{1}{4 pi varepsilon_{0}} frac{2 p}{r^{3}} ) along ( O C )
D. ( frac{1}{4 pi varepsilon_{0}} frac{p}{r^{3}} ) along ( C O )
12
774Charge ( Q ), is divided into two parts which are then kept some distance
apart. The force between them will be
maximum if the two parts are having the charge.
( ^{text {A }} cdot frac{Q}{2} ) each
в. ( frac{Q}{4} ) and ( frac{3 Q}{4} )
c. ( frac{Q}{3} ) and ( frac{2 Q}{3} )
D. ( e ) and ( (Q-e) ), where ( e= ) electronic charge
12
775(a) Derive a relation for electric field
due to an electric dipole at a point on the equatorial plane of the electric dipole. Draw necessary diagram.
(b) An electric dipole of charge ( pm 1 mu C ) exists inside a spherical Gaussian
surface of radius ( 1 c m ). Write the value
of outgoing flux from the Gaussian
surface.
(c) Potential on the surface of a
charged spherical shell of radius ( 10 mathrm{cm} )
is ( 10 V . ) Write the value of potential at ( 5 c m ) from its centre.
12
776The direction of induced current in the
case lis
A. from a to b and from c to d
B. from a to b and from fto e
( c . ) from b to a and from d to c
D. from b to a and from e to b
12
777( frac{pi}{r_{p}} )12
778The dimensional formula for electric
flux is
( mathbf{A} cdotleft[M L^{3} T^{-3} A^{-1}right] )
B ( cdotleft[M L^{3} T^{-2} A^{-1}right. )
( mathrm{c} cdotleft[M L^{1} T^{-1} A^{-1}right. )
D ( cdotleft[M L^{4} T^{-2} A^{-1}right] )
12
779Assertion
If a positively charged particle is placed in front of a spherical uncharged conductor. The number of lines of forces
terminating on the sphere will be more than those emerging from it.
Reason
The surface charge density at a point on the sphere nearest to the point charge will be negative and maximum in magnitude compared to other points on the sphere
A. If both Assertion and Reason are correct and Reason is the correct explanation of Assertion
B. If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion
c. If Assertion is correct but Reason is incorrect
D. If Assertion is incorrect but Reason is correct
12
780A particle ( A ) having a charge of ( 2.0 times )
( 10^{-6} C ) is held fixed on a horizontal
table. A second charged particle of mass ( 80 g ) stays in equilibrium on the table at a distance of ( 10 mathrm{cm} ) from the
first charge. The coefficient of friction
between the table and this second
particle is ( mu=0.2 . ) Find the range
within which the charge of this second
particle may lie.
12
781In column-I some equilibrium or nonequilibrium states are given. In columnII the charges ( +Q ) and ( -Q ) are fixed
while charges ( q ) or ( -q ) are moveable
point charges as shown in figure. Match the correct options
12
782Three concentric conducting spherical
shells of radii ( boldsymbol{R}, 2 boldsymbol{R} ) and ( boldsymbol{3} boldsymbol{R} ) carry
charges ( Q,-2 Q ) and ( 3 Q, ) respectively
Compute the potential at ( r=R ), and
the charges on the spheres of radii ( boldsymbol{R} )
and ( 3 R )
A ( cdot frac{Q+2 Q_{1}}{12 pi varepsilon_{0} R}, Q_{1}=frac{Q}{4}, Q_{2}=frac{7 Q}{2} )
в. ( frac{Q+2 Q_{1}}{12 pi varepsilon_{0} R}, Q_{1}=frac{Q}{2}, Q_{2}=frac{7 Q}{2} )
c. ( frac{Q+2 Q_{1}}{12 pi varepsilon_{0} R}, Q_{1}=frac{Q}{2}, Q_{2}=frac{7 Q}{4} )
D. ( frac{Q+2 Q_{1}}{12 pi varepsilon_{0} R}, Q_{1}=frac{Q}{4}, Q_{2}=frac{7 Q}{4} )
12
783Statement 1: A charge is outside the
Gaussian sphere of radius ( R ). Then
electric field on the surface of sphere is
zero

Statement 2: As ( oint vec{E} . overrightarrow{d s}=frac{q_{i n}}{varepsilon_{0}}, ) for the
sphere ( boldsymbol{q}_{boldsymbol{i n}} ) is zero, so ( oint overrightarrow{boldsymbol{E}} cdot overrightarrow{boldsymbol{d} s}=mathbf{0} )
A. Statement 1 is true, statement 2 is true and statement 2 is correct explanation for statement
B. Statement 1 is true, statement 2 is true and statement 2 is NOT the correct explanation for statement
c. Statement 1 is true, statement 2 is false
D. Statement 1 is false, statement 2 is true

12
784Most solid materials are classified as
insulators why?
A. They offer large resistance to the flow of electric current
B. They doesnt do anything
c. They offer large force to other particles
D. None
12
785In a regular polygon of ( n ) sides, each corner is at a distance ( r ) from the
centre. Identical charges of magnitude ( q ) are placed at ( (n-1) ) corners. The field
at the centre is
A. ( _{k^{2}} frac{q}{r^{2}} )
в. ( _{(n-1) k frac{q}{r^{2}}} )
c. ( frac{n}{n-1} k^{frac{q}{r^{2}}} )
D. ( frac{n-1}{n} k frac{q}{r^{2}} )
12
786Let a total charge ( 2 Q ) be distributed in a
sphere of radius ( R, ) with the charge
density given by ( rho(r)=k r, ) where ( r ) is
the distance from the centre. Two
charges ( A ) and ( B, ) of ( -Q ) each, are
placed on diametrically opposite points, at equal distance, a form the centre. If ( boldsymbol{A} )
and ( B ) do not experience any force, then:
A ( cdot a=frac{3 R}{2^{1 / 4}} )
B. ( a=frac{R}{sqrt{3}} )
C ( cdot a=8^{-1 / 4} R )
D . ( a=2^{-1 / 4} R )
12
787Two bodies ( X ) and ( Y ) carry charges ( -6.6 mu C ) and ( -5 mu C ).How many electrons should be transferred from ( X ) and Yso that they
acquire equal charges?
A ( .2 times 10^{12} )
B . ( 5 times 10^{14} )
( c cdot 5 times 10^{12} )
D. ( 5 times 10^{13} )
12
788Two small metallic spheres each of
mass ( mathrm{m} ) are suspended together with
strings of length ( l ) and placed together
When a quantum of charge ( boldsymbol{q} ) is
transferred to each the strings make an
angle of ( 90^{circ} ) with each other. The value
of ( q ) is
A ( cdot l /left(_{0} m gright) )
в. ( l /left(16_{o} m gright) )
( mathbf{c} cdot l /left(2_{o} m gright) )
D. none of these
12
789A particle of mass ( m ) and negative
charge ( q ) is thrown in a gravity free
space with speed ( u ) from the point ( A ) in the large nonconducting charged sheet with surface charge density ( sigma, ) as
shown in figure. The maximum
distance from ( A ) on sheet where the
particle can strike is ( frac{boldsymbol{x} epsilon_{0} boldsymbol{u}^{2} boldsymbol{m}}{boldsymbol{q} boldsymbol{sigma}} . ) Find ( boldsymbol{x} )
12
790The number of electrons present in ( 1 C ) of charge is
A ( cdot 4.25 times 10^{18} )
B. ( 6.25 times 10^{18} )
c. ( 3.25 times 10^{18} )
D. ( 2.25 times 10^{18} )
12
791A given charge situated at certain distance from an electric dipole in the end on position, experiences a force F. If the distance of charge is doubled, the force acting on the charge will be
A ( .2 F )
в. ( F / 2 )
c. ( F / 4 )
D. ( F / 8 )
12
792Electroscope is used
A. to detect and test small electric charges
B. to calculate the amount of electric charge flowing through the conductor in the given interval of time
C. to find out the presence of antimatter
D. to test the presence of magnetic field
12
793In a gold leaf electroscope, its stem is
A. wood
B. brass
c. glass
D. ebonite
12
794Find the magnitude of the force on a charge of ( 12 mu C ) placed at a point where the potential gradient has a magnitude of ( 6 times 10^{5} V m^{-1} )12
795A non conducting sphere of radius R is filled with uniform volume charge
density – ( rho . ) The center of this sphere is displaced from the origin by ( vec{d} ). The electric field ( vec{E} ) at any point ( P ) having position vector inside the sphere is :
( A )
B ( cdot frac{rho}{3 varepsilon_{0}}(vec{r}-vec{d}) )
c. ( frac{rho}{3 varepsilon_{0}}(vec{d}-vec{r}) )
D. ( frac{rho}{3 varepsilon_{0}}(vec{r}) )
12
796Figure shows a charge array known as an electric quadrupole. For a point on the axis of the quadrupole, obtain the dependence of potential on ( r ) for ( r / a>>1 ) and contrast your results with that due to an electric dipole, and an electric monopole (i.e., a single charge).12
797Due to an electric dipole shown in fig., the
electric field intensity is parallel to dipole
axis
( A cdot ) at ( P ) only
B. at Qonly
c. both at ( P ) and at ( Q )
D. neither at ( P ) nor at ( Q )
12
798An electric pole of dipole moment ( underset{boldsymbol{p}}{rightarrow} ) is lying along uniform electric field ( overrightarrow{boldsymbol{E}} . ) The work done in rotating the dipole by ( 90^{circ} ) is:-
A ( cdot sqrt{2} ) pE
B. ( frac{p}{2} )
c. 2 p
D. pE
12
799If the surface is placed parallel to the electric field, then
A. infinite electric flux will pass through the surface
B. no electric flux will pass through the surface.
c. finite electric flux will pass through the surface.
D. variable electric flux will pass through the surface
12
800A charged ball B hangs from a silk
thread ( S ) which makes an angle ( theta ) with a
arge charged conducting sheet ( mathrm{P} ) as shown in the given figure. The surface charge density ( sigma ) of the sheet is
proportional to :
( A cdot cos theta )
B ( cdot cot theta )
( c cdot sin theta )
D. ( tan theta )
12
801What is the S.I. unit of charge?
A. Ampere
B. Charge
c. coulomb
D. volt
12
802The number of electrons that must be
removed from an electrically neutral silver dollar to give it a charge of ( +2.4 C )
is
A ( .2 .5 times 10^{19} )
B. ( 1.5 times 10^{19} )
c. ( 1.5 times 10^{-19} )
D. ( 2.5 times 10^{-19} )
12
803In fig., a cone lies in a uniform electric
field E. Determine the electric flux
entering the cone
A. Flux ( phi=E A=2 E R h )
B. Flux ( phi=E A=7 E R h )
c. Flux ( phi=E A=9 E R h )
D. Flux ( phi=E A=E R h )
12
804Induced charge resides at/in the
A. bulk of the object
B. centre of the object
c. surface of the object
D. All of the above
12
805An electrolyte is:
A. a cell
B. a metal
C. a liquid that conducts electricity
D. sugar
12
806A charge ( +q ) is fixed to each of three
corners of a square. On the empty corner a charge ( Q ) is placed such that there is no
net electrostatic force acting on the
diagonally opposite charge. Then:
A. ( Q=-2 q )
в. ( Q=-2 sqrt{2} q )
c. ( Q=-sqrt{2} q )
D. ( Q=-4 q )
12
807During electrification by friction
A. Proton are transferred from one body to another body
B. Neutrons are transferred from one body to another body
C. Electrons are transferred from one body to another body
D. None
12
808A solid metallic sphere is placed in a
uniform electric field. Which of the
curves shown in figure represent the
lines of force correctly?
( mathbf{A} cdot(a) )
B. ( (b) )
( c cdot(c) )
( mathbf{D} cdot(d) )
12
809A point charge is brought in an electric field. The electric field at a nearby point This question has multiple correct options
A. will increase if the charge is positive
B. will decrease if the charge is negative
c. may increase if the charge is positive
D. may decrease if the charge is negative
12
810State Gauss’s theorem and state its any
‘two’ applications.
12
811Electric charges having same magnitude of electric charge ‘q’, coulombs are placed at ( x=1 mathrm{m}, 2 mathrm{m}, 3 mathrm{m} ) ( 4 m, 8 m, dots dots ) and so on. If any two consecutive charges have opposite sign but the first charge is necessarily positive, what will be the potential at ( x= )
O?
A ( cdot frac{2 h q}{3} )
B. zero
C. ( frac{1}{4 pi varepsilon_{0}}left(frac{2 q}{3}right) )
D. ( frac{1}{4 pi varepsilon_{0}}(2 q) )
12
812If 10 million electrons are removed from a
neutral body, then the charge on the body
is :
A ( cdot 1.2 times 10^{-12} C )
B. ( +1.6 times 10^{-12} C )
c. ( -1.6 times 10^{-13} C )
D. ( 10^{-12} C )
12
813A point charge ( +boldsymbol{q} & ) mass ( 100 g boldsymbol{m} )
experiences a force of ( 100 N ) at a point
at a distance ( 20 mathrm{cm} ) from a long infinite uniformly charged wire. If it is released its speed is ( 20 sqrt{ln x} ) m/ ( s ) when
it is at a distance ( 40 mathrm{cm} ) from wire. Find
( boldsymbol{x} )
12
814Two metallic spheres ( A ) and ( B ) kept on
insulating stands are in contact with
each other. A positively charged rod ( P ) is
brought near the sphere ( A ) as shown in
the figure. The two spheres are
separated from each other, and the rod
( P ) is removed. What will be the nature of
charges on spheres ( boldsymbol{A} ) and ( boldsymbol{B} ) ?
12
815(a) Consider an arbitrary electrostatic field configuration. A small test charge is placed at a null point (i.e., where ( mathrm{E}= )
0) of the configuration. Show that the equilibrium of the test charge is necessarily unstable.
(b) Verify this result for the simple configuration of two charges of the same magnitude and sign placed a certain distance apart.
12
816Obtain the expression for the intensity of electric field near a uniformly
charged straight wire of infinite length with the help of Gauss theorem.
12
817A cube of side a carries a charge ( q ) each at the corners of a cube.Then the
potential at the centre of cube is then
going to be
A ( cdot frac{8 q}{pi varepsilon_{0} a} )
в. ( frac{4 q}{4 pi varepsilon_{0} a} )
c. ( frac{4 q}{sqrt{3} pi varepsilon_{0} a} )
D. ( frac{2 q}{pi varepsilon_{0} a} )
12
818Which of the following devices is used to detect the presences of a charge on a body?
A. Multimeter
B. Electroscope
c. Angiogram
D. Microscope
12
819A charge ( Q ) is to be divided into two parts such the force between them is
maximum. They should be divided as
A ( cdot frac{Q}{4}, frac{3 Q}{4} )
B . ( frac{a}{3}, frac{20}{3} )
c. ( frac{a}{8}, frac{7 Q}{8} )
D. ( frac{Q}{2}, frac{a}{2} )
12
820Specific heat capacity is for
conductors of heat and for
insulators of heat.
A. low, low
B. low, high
c. high, high
D. high, low
12
821A solid conducting sphere having a
charge ( Q ) is surrounded by an
uncharged concentric conducting spherical shell. Let the potential difference between the surface of the
solid sphere and that of the outer surface of the shell be ( V ). If the shell is
now given a charge of ( -3 Q . ) Find out the
new potential difference between the
two surface is:
( mathbf{A} cdot V )
B. ( 2 V )
c. ( 4 V )
( mathbf{D} cdot-2 V )
12
822Consider the electric dipole moment ( (p=2 q a) ) shown in the figure. The
electric field at a point ( boldsymbol{P}(boldsymbol{x}, boldsymbol{y}, boldsymbol{0}) ) in the
polar coordinate system is :
A ( cdot frac{k_{e} p}{r^{3}}[(2 cos theta) hat{r}-(sin theta) hat{theta}] )
B. ( frac{k_{e} p}{r^{3}}[(2 cos theta) hat{r}+(sin theta) hat{theta} )
c. ( frac{k_{e} p}{r^{3}}[-(2 cos theta) hat{r}+(sin theta) hat{theta} )
D. ( frac{k_{e} p}{r^{3}}[-(2 cos theta) hat{r}-(sin theta) hat{theta} )
12
823Find electric field
A ( cdot frac{2 m a V^{2}}{e d^{2}} )
B. ( frac{m a V^{2}}{e d^{2}} )
c. ( frac{2 m a V^{2}}{2 e d^{2}} )
D. ( frac{2 m a V^{3}}{e d^{3}} )
12
824If a conductor has ( 10^{8} ) number of
electrons, then the total charge of the conductor is:
A. ( +1.6 times 10^{-19} mathrm{C} )
В. ( -1.6 times 10^{-19} mathrm{c} )
c. ( +1.6 times 10^{-11} mathrm{c} )
D. ( -1.6 times 10^{-11} mathrm{C} )
12
825An electric dipole is kept in a uniform electric field, it experiences
A. a force and a torque
B. a force, but no torque
c. a torque, but no force
D. neither a force nor a torque
12
826We have two electric dipoles. Each dipole consists of two equal and opposite point charges at the ends of an insulating rod of length d. The dipoles sit along the ( x ) -axis a distance ( r ) apart, oriented as shown in figure. Their separation ( r>>d ). The dipole on the left:
This question has multiple correct options
A. wil feel a force to the left
B. will feel a force to the right
c. will feel a torque trying to make it rotate counterclockwis
D. will feel no torque
12
827What is a material called, if it does not
allow electric current to flow through it? (Conductor, Insulator)
12
828In a Helium gas discharge tube every second ( 40 times 10^{18} H e^{+} ) (ions) move
towards the right through a cross section of the tube, while n electrons
move to the left in the same time. If the
current in the tube is ( 8 A ) towards right
then ( n=? )
A ( cdot 10 times 10^{18} )
B. 3 ( times 10^{19} )
( c cdot 3 times 10^{20} )
D. 3 ( times 10^{2} )
12
829A smooth dielectric slab ( A ) of mass ( m )
and dielectric constant ( k ) is placed
between the plates of a parallel plate capacitor and connected to another
block ( B ) of equal mass ( m ) through a
string and pulley arrangement as shown in the figure.
The capacitor plates with separation ( delta )
and width ( b ) are connected to a battery
of emf ( boldsymbol{E} ) as shown in the figure. The
pulley and string are massless and ( boldsymbol{E}=sqrt{frac{boldsymbol{m} boldsymbol{g} boldsymbol{delta}}{boldsymbol{b}(boldsymbol{k}-mathbf{1}) in_{0}}} )
12
830A conducting sphere of radius ( boldsymbol{R} ) having
charge ( q ) is joined to another
conducting sphere of radius ( 2 R ) having
charge ( -2 q . ) The charge flowing between them will be
( mathbf{A} cdot mathbf{q} )
в. ( frac{2 q}{3} )
c. ( frac{q}{3} )
D. ( frac{4 q}{3} )
12
831Consider a neutral conducting sphere. A positive point charge is placed outside the sphere. The net charge on the sphere is then,
A. negative and distributed uniformly over the surface of the sphere
B. negative and appears only at the point on the sphere closest to the point charge
c. negative and distributed non-uniformly over the entire surface of the sphere
D. zero
12
832Identify the wrong statement.
( A . ) In an electric field two equipotential surfaces can never intersect
B. A charged particle free to move in an electric field shall always move in the direction of ( E )
C. Electric field on the surface of a charged conductor is always normal to the surface
D. The electric potential decrease along a line of force in an electric an electric field
12
833There is a point charge q located at the centre of a cube. What is the electric
flux of this point charge, through a face of the cube?
A ( cdot frac{q}{epsilon_{0}} )
в. ( frac{q}{6 epsilon_{0}} )
c. ( frac{q}{3 epsilon_{0}} )
D. It will depend on the size of the cube
12
834Which of the following charges is/are impossible?
A ( cdot 4.8 times 10^{-18} mathrm{C} )
B . ( 5.8 times 10^{-18} mathrm{C} )
c. ( 12.8 times 10^{-18} mathrm{C} )
D . ( 20.8 times 10^{-18} mathrm{C} )
12
835An electron moving with a constant velocity ( v ) along ( X ) -axis enters a uniform electric field applied along Y-axis. Then,
the electron moves
A. with uniform acceleration along Y-axis
B. without any acceleration along Y-axis
C ( . ) in a trajectory represented as ( y=a x^{2} )
D. in a trajectory represented as ( y=a x )
E. with uniform deceleration along ( mathrm{x} ) -axis
12
836Assertion
A small electric dipole is moved translationally from higher potential to lower potential in uniform electric field.
Work done by electric field is positive.
Reason

When a positive charge is moved from
higher potential to lower potential, work
done by electric field is positive.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect

12
837If flux in a coil changes by ( Delta phi, ) and the resistance of the coil is ( R ), prove that the charge flown in the coil during the flux change is ( frac{Delta phi}{R} . ) (Note: It is independent of the time taken for the change in flux)12
838The diagram shows a sphere of radius
( boldsymbol{R} ) that carries a charge ( boldsymbol{Q} ) uniformly
distributed throughout its volume. ( A )
Gaussian sphere of radius ( a ) is
imagined that is concentric to the
charged sphere.
If ( a<R, ) what is the charge enclosed in
the Gaussian surface?
( ^{mathbf{A}} cdot Q_{e n c}=Q frac{a^{4}}{R^{4}} )
( ^{mathbf{B}} cdot Q_{e n c}=Q frac{a}{R} )
( ^{mathbf{C}} Q_{e n c}=Q frac{a^{2}}{R^{2}} )
( ^{mathrm{D}} Q_{e n c}=Q frac{a^{3}}{R^{3}} )
( ^{mathrm{E}} cdot Q_{e n c}=Q frac{a^{5}}{R^{5}} )
12
839Calculate force on an electron in a
uniform electric field of ( 5 times 10^{4} mathrm{N} / mathrm{C} ) due
north.
12
840Which unit is equivalent to the coulomb?

This question has multiple correct options
A. ampere – second
B. joule per volt
c. watt per ampere
D. watt per volt

12
841A point charge ( q ) is at centre of an
unchanged spherical conducting shell
of inner radius ( a ) and outer radius ( b )
Work needed to move the charge out to
infinity will be
( ^{mathbf{A}} cdot frac{q^{2}}{4 pi varepsilon_{0}}left(frac{1}{a}-frac{1}{b}right) )
B. ( frac{1}{8 pi epsilon_{0}} frac{q^{2}}{a} )
( ^{mathbf{c}} cdot frac{q^{2}}{8 pi epsilon_{0}}left[frac{1}{b}-frac{1}{a}right] )
( ^{mathrm{D}} cdot frac{q^{2}}{8 pi epsilon_{0}}left[frac{1}{a}-frac{1}{b}right] )
12
842A solid insulating sphere of radius ( boldsymbol{R} ) is
given a charge ( Q ). If at a point inside the
sphere the potential is 1.5 times the potential at the surface, this point will
be:
A. at a distance of ( 2 R / 3 ) form the centre
B. at the centre
c. at a distance of ( 2 R / 3 ) form the surface
D. data insufficient
12
843A charge is kept at the centre of a shell. Shell has charge Quniformally distibuted over its surface and radius ( mathrm{R} )
The force on the central charge due to the shell is :
A. towards left
B. towards right
c. upward
D. zero
12
844What is the did
charge ( q ) is projected towards an
infinitely long line of a charge (having linear density of charge ( +lambda ) ) from a
distance ( t_{0} . ) The direction of initial
velocity ( v_{0} ) makes an angle ( 30^{circ} ) with the
normal to the line of charge as shown in
figure. The minimum distance of
approach of the charge particle with the line of charge will be (neglect gravity). ( operatorname{take} lambda=frac{pi varepsilon_{0} m v_{0}^{2}}{4 q} )
( A cdot frac{r_{0}}{e} )
B. ( frac{r_{0}}{e^{2}} )
c. ( frac{r_{0}}{e^{3}} )
D. ( frac{r_{0}}{2} )
12
845Consider 3 identical charges of charge
q placed at the vertices of an equilatera triangle, as shown in the figure. What is the force on one of the charges due to
the others?
( ^{mathbf{A}} cdot frac{1}{4 pi epsilon_{0}} frac{q^{2}}{l^{2}} )
B. ( frac{sqrt{2}}{4 pi epsilon_{0}} frac{q^{2}}{l^{2}} )
C. ( frac{sqrt{3}}{4 pi epsilon_{0}} frac{q^{2}}{l^{2}} )
D ( cdot frac{2 sqrt{3}}{4 pi epsilon_{0}} frac{q^{2}}{l^{2}} )
12
846Two fixed charges ( A ) and ( B ) of ( 5 mu C ) each
are separated by a distance of ( 6 mathrm{m} . mathrm{C} ) is the mid point of the line joining A and B. A charge ‘Q’ of ( -5 mu C ) is shot perpendicular to the line joining A and B
through ( C ) with a kinetic energy of 0.06
J. The charge ‘Q’ comes to rest at a point
D. The distance CD is?
12
847Three charges ( Q,+q ) and ( +q ) are placed
at the vertices of a right-angled isosceles triangle between as shown. The net electrostatic energy of the configuration is zero if ( Q ) is equal to
( ^{A} cdot frac{-2 q}{1+sqrt{2}} )
в. ( frac{2 q}{2+sqrt{2}} )
( c cdot-2 q )
D. ( +q )
12
848An oil drop is negatively charged and weights ( 5 times 10^{-4} N ). The drop is
suspended in an electric field intensity of ( 2.6 times 10^{4} N / C ). The number of
electrons the oil drop is in ( boldsymbol{x} times mathbf{1 0}^{mathbf{1 0}} )
Then ( x ) is
A. 8
B. 10
( c cdot 16 )
D. 12
12
849Four charges are arranged at the
corners of a square ABCD as shown in
figure. The force on a positive charge
kept at the centre of the square is:
A. zero
c. along diagonal BD
D. perpendicular to the side AB
12
850The cube as shown in Fig. has sides of length ( L=10.0 mathrm{cm} . ) The electric field is
uniform, has a magnitude ( boldsymbol{E}=mathbf{4 . 0 0} times )
( 10^{3} N C^{-1}, ) and is parallel to the ( x y- )
plane at an angle of ( 37^{circ} ) measured from
the ( +x-a x i s ) towards the ( +y-a x i s )
Electric flux passing through surface ( boldsymbol{S}_{6} )
is
A ( cdot 24 N m^{2} C^{-1} )
B. ( -24 N m^{2} C^{-1} )
( mathbf{c} cdot 32 N m^{2} C^{-1} )
D. ( -32 N m^{2} C^{-1} )
12
851If the symmetry is such that you can find a surface on which the electric field
is constant, then evaluating the electric flux can be done by
A. dividing the value of the field by the area of the Gaussian surface.
B. multiplying the value of the field times the area of the Gaussian surface
c. multiplying the square of the value of the field times the area of the Gaussian surface.
D. dividing the square of the value of the field times the area of the Gaussian surface
12
852A charged particle ‘q’ lies at ‘P’ and the line ( mathrm{PC} ) is perpendicular to the surface of ( A B C ) (part of disc). Find the flux passing through the surface ABC.
A ( cdot frac{q}{4 varepsilon_{0}} )
в. ( frac{q}{16 varepsilon_{0}} )
c. ( frac{q}{32 varepsilon_{0}} )
D. ( frac{q}{48 varepsilon_{0}} )
12
853A glass rod rubbed with silk is brought
near the fur rubbed with an ebonite rod.
What will be your observation between
them?
A . Attraction
B. Repulsion
c. No change
D. cant say
12
854There is a uniform electrostatic field in
a region. The potential at various points on a small sphere central at ( P ), in the region, is found to vary between the limits ( 589.0 mathrm{V} ) to ( 589.8 mathrm{V} ). What is the
potential at a point on the sphere whose
radius vector makes an angle of ( 60^{circ} )
with the direction of the field?
A . ( 589.5 mathrm{v} )
B. ( 589.2 v )
c. ( 589.4 mathrm{v} )
D. 589.6
12
855Assertion : Electric lines of force never
cross each other.
Reason: Electric field at a point superimpose to give one resultant electric field.
A. If both assertion and reason are true but the reason is the correct explanation of assertion.
B. If both assertion and reason are true but the reason is not the correct explanation of assertion
c. If assertion is true but reason is false
D. If both the assertion and reason are false.
E. If reason is true but assertion is false
12
856There are 27 drops of a conducting fluid. Each drop has radius ( r, ) and each of
them is charged to the same potential ( V_{1} ).They are then combined to form a bigger drop.The potential of the bigger drop is ( V_{2} ).Find the ratio ( V_{2} / V_{1} ). Ignore
the change in density of the fluid on combining the drops.
12
857Find the electric field at ( z<-mathbf{0 . 5 d} )
( mathbf{A} cdot E=0 )
B ( cdot E=-frac{sigma}{epsilon_{0}} hat{k} )
( mathbf{c} cdot E=frac{sigma}{epsilon_{0}} hat{k} )
D. ( E=frac{sigma}{2 epsilon_{0}} hat{k} )
12
858( q_{1}, q_{2}, q_{3}, ) and ( q_{4} ) are point charges located at points as shown in the figure and ( mathrm{S} ) is a spherical Gaussian surface
of radius R. Which of the following is
true according to the Gauss’s law?
A ( cdot oint_{5}left(vec{E}_{1}+vec{E}_{2}+vec{E}_{3}right) cdot d vec{A}=frac{q_{1}+q_{2}+q_{3}}{2 varepsilon_{0}} )
B.
c. ( oint_{5}left(vec{E}_{1}+vec{E}_{2}+vec{E}_{3}right) cdot d vec{A}=frac{left(q_{1}+q_{2}+q_{3}+q_{4}right)}{varepsilon_{0}} )
D. None of the above
12
859The radius of hollow metallic sphere is ( r ) If the potential difference between its surface and a at a distance ( 3 r ) from its
centre is v then the electric field
intensity at a distance of ( 3 r ) its centre is:
A. v/2r
B. ( vee / 3 ) r
c. ( vee / 4 r )
D. V/6
12
860How does the electric field(E) between
the plates of a charged cylindrical capacitor vary with the distance r from the axis of the cylinder?
A ( cdot E propto frac{1}{r^{2}} )
в. ( quad E propto frac{1}{r} )
c. ( E propto r^{2} )
D. ( E propto r )
12
861A proton and an electron are placed in a
uniform electric field.
A. The electric forces acting on them will not be equal.
B. The magnitudes of the forces will be equal.
C. Their accelerations will be equal.
D. None of the above
12
862So that the torque acting on it is zero12
863Electric charge is always conserved in physical process.
A. True
B. False
12
864The distance between the two charges
( +q ) and ( -q ) of a dipole is ( r . ) The
intensity at a point on the axial line at a
distance ( x ) from the centre of dipole is
proportional to
A ( cdot frac{q}{x^{2}} )
в. ( frac{q r}{x^{2}} )
c. ( frac{q}{x^{3}} )
D. ( frac{q r}{x^{3} r} )
12
865Given a uniform electric field ( overrightarrow{boldsymbol{E}}=mathbf{2} times )
( 10^{3} hat{i} mathrm{N} / mathrm{C} ). Find the flux of this field
through a square of side ( 20 mathrm{cm}, ) whose plane is parallel to the ( y ) -z plane. What would be the flux through the same square, if the plane makes an angle of
( 30^{circ} ) with the ( x ) -axis?
12
866Assertion
A small power circuit that is isolated from ground typically is less dangerous.
Reason
Its contacting just one power wire will
not form a complete circuit path, and it
is too small to collect large dangerous
atmospheric charge potentials.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
867The rupture of air medium occurs at
( boldsymbol{E}=mathbf{3} times mathbf{1 0}^{mathbf{6}} boldsymbol{V} / boldsymbol{m} . ) The maximum
charge that can be given to a sphere of diameter 5 m will be (in coulomb):
A ( .2 times 10^{-2} )
B . ( 2 times 10^{-3} )
c. ( 2 times 10^{-4} )
D. ( 2 times 10^{-5} )
12
868The laws of forces that govern the force between two electric charges were discovered by :
B. Ampere
( c . ) onm
D. Coulumb
12
869Two point charges ( +q ) and ( -q ) are held fixed at ( (-d, 0) ) and ( (d, 0) ) respectively of
a ( x-y ) coordinate system. Then:
A. The electric field ( mathrm{E} ) at all points on the axis has the same direction
B. Work has to be done in bringing a test charge from ( infty ) to the orgin
C. Electric field at all points on y-axis is along x-axis
D. The dipole moment is 2qd along the x-axis
12
870If a charge ( q ) is placed at the centre of the line joining two equal charges ( Q ) such that the system is in equilibrium
then the value of ( q ) is :
A ( . Q / 2 )
в. ( -Q / 2 )
c. ( Q / 4 )
D. ( -Q / 4 )
12
871A cylinder of length ( L ) and radius b has
its axis coincident with the x-axis. The
electric field in this region is ( overrightarrow{boldsymbol{E}}=mathbf{2 0 0 hat { boldsymbol { i } }} )
Find the flux through the left end of cylinder.
( mathbf{A} cdot mathbf{0} )
в. ( 200 pi b^{2} )
c. ( 100 pi b^{2} )
D. ( -200 pi b^{2} )
12
872A charged rod is brought near a
negatively charged pith ball electroscope. What conclusion would you draw about the charge on the rod if pith ball moves away from the rod?
A. Positive
B. Negative
c. No charge
D. can’t say
12
873A copper ball of radius ( 1 mathrm{cm} ) work
function ( 4.47 e V ) is irradiated with
ultraviolet radiation of wavelength ( 2500 A ). The effect of irradiation results
in the emission of electrons from the
ball. Further the ball will require charge and due to this there will be finite value
of the potential on the ball. The charge acquired by the ball is:
A ( .5 .5 times 10^{-13} mathrm{C} )
В. ( 7.5 times 10^{-13} C )
c. ( 4.5 times 10^{-12} mathrm{C} )
D. ( 2.5 times 10^{-11} C )
12
874If a point lies at a distance ( ^{prime} x^{prime} ) from the
mid point of the dipole, the electric potential at this point is proportional to
A ( cdot frac{1}{x^{2}} )
B. ( frac{1}{x^{3}} )
c. ( frac{1}{x^{4}} )
D. ( frac{1}{x^{3 / 2}} )
12
875The magnitude of electric force on ( 2 mu c )
change placed at the centre ( O ) of two
equilateral triangle each of side ( 10 mathrm{cm} )
as shown in figure is ( P ). If charge
( A, B, C, D, E & F ) are
( 2 mu c, 2 mu c, 2 mu c,-2 mu c,-2 mu c,-2 mu c )
respectively, then ( boldsymbol{P} ) is:
A . ( 21.6 N )
B. ( 64.8 N )
( c )
D. ( 43.2 N )
12
876Four point charges, each of ( +q, ) are rigidly fixed at the four corners of a square planar soap film of side ( a ). The
surface tension of the soap film is ( gamma ) The system of charges and planar film are in equilibrium, and ( boldsymbol{a}=boldsymbol{k}left[frac{boldsymbol{q}^{2}}{gamma}right]^{1 / N}, ) where
( k^{prime} ) is a constant. Then ( N ) is:
( A cdot 3 )
B. 2
( c cdot 4 )
( D )
12
877Electric intensity is:
A . a scalar quantity
B. a vector quantity
C. neither scalar nor vector
D. sometimes scalar and sometimes vector
12
878Two point charges ( boldsymbol{q}_{1}=-boldsymbol{4} boldsymbol{mu} boldsymbol{C} ) and
( q_{2}=8 mu C ) are lying on the ( y ) -axis. They
are equidistant from the point ( boldsymbol{P} ), which
lies on the ( x ) -axis. A small object of
charge ( boldsymbol{q}_{0}=8 mu C ) and mass ( boldsymbol{m}=12 boldsymbol{g} ) is
placed at ( P . ) When it is released, what is
its acceleration in ( m s^{-2} ? )
(Neglect the effect of gravity)
B. ( 9 hat{i}+3 sqrt{3} hat{j} )
c. ( 3 hat{i}+3 sqrt{3} hat{j} )
D. ( 3 sqrt{3 i}+3 hat{j} )
12
879There are two unknown charges, ( Q_{1} ) and
( Q_{2} . ) A positive charge is placed at P.P is
closer to ( Q_{2} ) than ( Q_{1} ). If the net electric
force acting on the charge at P is zero, then conclusion is :
[
]
A. Both ( Q_{1} ) and ( Q_{2} ) are positive
B. Both ( Q_{1} ) and ( Q_{2} ) are negative
C. Both ( Q_{1} ) and ( Q_{2} ) have opposite signs
D. Both ( Q_{1} ) and ( Q_{2} ) have the same sign, but the
magnitude of ( Q_{1} ) is greater than the magnitude of ( Q_{2} )
E. ( Q_{1} ) and ( Q_{2} ) have same sign, but the magnitude of ( Q_{2} ) is greater than the magnitude of ( Q_{1} )
12
880Two metallic solid sphere of radii ( mathrm{R} ) and
( 2 R ) are charged such that both of them
have same charge density ( sigma ). If the
sphere are located far away from each other and connected by a thin conducting wire,the new charge density on bigger sphere is:
12
881In filling the gasoline tank of an
aeroplane the metal nozzle of the hose
from the gasoline truck is always carefully connected to the metal of the aeroplane by a wire before the nozzle is inserted in the tank. Explain, why?
12
882A charge ( +mathrm{Q} ) is located in space at the
point ( (boldsymbol{x}=mathbf{1} boldsymbol{m}, boldsymbol{y}=mathbf{1 0 m}, boldsymbol{z}=mathbf{5} boldsymbol{m}) )
What is the total electric flux that
passes through the yz-plane?
A ( cdot frac{Q}{varepsilon_{0}} )
в. ( frac{Q}{3 varepsilon_{0}} )
c. ( frac{Q}{6 varepsilon_{0}} )
D ( cdot frac{Q}{2 varepsilon_{0}} )
12
883Figure shows two conducting spheres separated by large distance and of
radius ( 2 mathrm{cm} ) and ( 3 mathrm{cm} ) containing
charges ( 10 mu mathrm{C} ) arc ( 20 mu mathrm{C} ) respectively
When the spheres are connected by a conducting wire then find out following:
¡)Ratio of the final charge.
ii)Final charge on each sphere.
iii)Ratio of final charge densities.
12
884A unit positive charge is moved along
the circumference of a circle due to the
attraction of a ( -100 mathrm{C} ) charge at the centre of the circle. Then the work done
in the process is
A. negative work of 100 J
B. positive work of 100 J
c. zero
D. ( frac{Q .1}{4 pi epsilon_{0} r} )
12
885A small sphere of mass ( m ) and electric
charge ( boldsymbol{q}, ) is suspended by a light thread. A second sphere carrying a
charge ( q_{2} ) is placed directly below the
first sphere at a distance ( ^{prime} d^{prime} ) away. Then
A. tension in thread may reduce to zero if the spheres are positively charged
B. tension in thread may reduce to zero if the spheres are oppositely charged
c. tension in thread can never be zero
D. tension in thread is independent of the nature of the charges
12
886Figure shows a charge ( q ) placed at the centre of a hemisphere. A second
charge ( Q ) is placed at one of the positions ( A, B, C ) and ( D . ) In which position(s) of this second charge, the flux of the electric field through the
hemisphere remains unchanged?
his question has multiple correct options
( A )
3.
( c )
( D )
12
887A point charge ( +10 mu C ) is at a distance
5 ( c m ) directly above the centre of a
square of side ( 10 mathrm{cm} ), as shown in the
figure. What is the magnitude of the electric flux through the square?
A ( cdot 1.2 times 10^{5} mathrm{Nm}^{2} / mathrm{C} )
B . ( 1.9 times 10^{5} mathrm{Nm}^{2} / mathrm{C} )
c. ( 3.2 times 10^{5} mathrm{Nm}^{2} / mathrm{C} )
D. ( 4.2 times 10^{5} mathrm{Nm}^{2} / mathrm{C} )
12
888State whether True or False:
In a uniform electric field, the dipole experiences no net force; but experiences a torque having a relation with ( P ) and ( E ) which is given by ( vec{P} times vec{E} )
where the parameters ( P ) and ( E ) have their usual meaning.
A. True
B. False
12
889When a charged rod is brought near the disc of a negatively charged gold leaf electroscope, it is observed that the divergence of leaves decreases.What inference do you draw about the charge
on the rod?
A. Rod is positively charged
B. Rod is negatively charged
c. Rod has no charge
D. cant say
12
890Two short electric dipoles are placed as
shown ( ( r ) is distance between their
centres). The energy of electric interaction between these dipoles will
be:
( left(C text { is centre of dipole of moment } boldsymbol{P}_{2}right) )
( A )
B. ( -frac{2 k P_{1} P_{2} cos theta}{r^{3}} )
c. ( frac{-2 k P_{1} P_{2} sin theta}{r^{3}} )
D.
12
891If both the dipoles are free to rotate
about the axes, perpendicular to the plane xoy and passing through 0 and ( A ) respectively, then they will orient themselves such that
A ( cdot vec{p}_{1} ) is at right angles to ( vec{p}_{2} )
B. both ( vec{p}_{1} ) and ( vec{p}_{2} ) are along ( overrightarrow{O A} )
c. ( overrightarrow{p_{1}} ) is parallel to ( vec{p}_{2} )
D. ( overrightarrow{p_{1}} ) is antiparallel to ( overrightarrow{p_{2}} )
12
892The electric force on a unit positive charge at a given point in a system of charges is called
A . electric dipole moment
B. electric field intensity
c. electric potential
D. electric charge
12
893Four particle each having a charge ( boldsymbol{q} )
are placed on the four vertices of a
regular pentagon. The distance of each
corner from the centre is ( a ). Find the
electric field at the centre of the
Pentagon.
A ( cdot frac{q}{4 pi epsilon_{0} a^{2}} ) Along OE
B. ( frac{q}{3 pi epsilon_{0} a^{2}} ) Along OE
c. ( Z ) ero
D. ( frac{q}{2} ) Along EO
12
894Two objects with unlike charges will:
A. attract each other
B. repel each other
C. neither attract nor repel
D. either attract or repel
12
charges along the ( x-, y- ) and z-axes,
respectively. The charge density, i.e.,
charge per unit length of each wire is ( lambda: )
A ( cdot frac{lambda}{3 pi varepsilon_{0} a}(hat{i}+hat{j}+widehat{k}) )
В ( cdot frac{lambda}{2 pi varepsilon_{0} a}(hat{i}+hat{j}+widehat{k}) )
c. ( frac{lambda}{2 sqrt{2} pi varepsilon_{0} a}(hat{i}+widehat{j}+widehat{k}) )
D. ( frac{sqrt{2} lambda}{(hat{i}+hat{j}+widehat{k})} )
12
896Identify the correct process that happens here:
A. A has gained 2 electrons and B has lost 2 electrons
B. A has gained 2 electrons and B has gained 2 electrons
C. A has lost 2 electrons and B has gained 2 electrons
D. A has lost 2 electrons and ( B ) has lost 2 electrons
12
897Coulomb’s law is a confirmation
of
A. inverse cube law
B. product law
c. inverse square law
D. None of the above
12
898A charge ( +10^{-9} C ) is located at the origin in free space and another charge
( Q ) at ( (2,0,0) . ) If the ( X ) -component of the electric field at (3,1,1) is zero, calculate the value of ( Q . ) Is ( Y- ) component zero at (3,1,1)( ? )
12
899When n small drops of a conducting
liquid, each of surface charge density ( sigma )
form a big drop of radius ( R ), then:
A ( . ) potential becomes ( n^{1 / 3} ) times original potential and charge density decreases to ( n^{1 / 3} ) times original charge density
B. potential becomes ( n^{2 / 3} ) times and charge density increases to ( n^{1 / 3} ) times original charge density
C . potential and charge density decrease to ( n^{4 / 3} ) times original values
D. potential and charge density increase to n times original values
12
900Four charges ( +boldsymbol{Q},-boldsymbol{Q},+boldsymbol{Q} ) and ( -boldsymbol{Q} ) are
situated at the corners of a square; in a
sequence then at the centre of the
square:
A. ( E=0, V=0 )
в. ( E=0, V neq 0 )
c. ( E neq 0, V=0 )
D. ( E neq 0, V neq 0 )
12
901An electric dipole coincides on the zaxis and its centre coincides with the
origin of the cartesian coordinate system. The electric field at an axial
point at a distance ( z ) from the origin is
( E(z) ) and the electric field at an equatorial point at a distance ( y ) from
the origin is ( boldsymbol{E}(boldsymbol{y}) )
Given that ( y=z>>a, ) which is true?
A. ( E(z) ) and ( E(y) ) are perpendicular
B. ( E(z) ) and ( E(y) ) are parallel
C. ( E(z) ) and ( E(y) ) are at ( 45^{circ} ) to one another
D. None of these
12
902A balloon gets negatively charged by
rubbing ceilings of a wall.
A. This implies that the wall is positively charged.
B. This implies that the wall is negatively charged.
C. This does not imply that the wall is positively charged.
D. None of these
12
903A body has a positive charge of ( 8 x )
( 15^{-19} C . ) It has
A. an excess of ( 5 e^{-} )
B. a deficiency of ( 5 e^{-} )
c. an excess of ( 8 e^{-} )
D. a deficiency of ( 8 e^{-} )
12
904The electric potential at a point on the equatorial line of an electric dipole is :
A. directly proportional to distance
B. inversely proportional to distance
c. inversely proportional to square of the distance
D. none of these
12
905The Sl unit of electric flux density is
A. ( N / C )
в. ( N m^{2} / C )
c. ( N m / C )
D. ( N m^{2} )
12
906Two positive charges ( boldsymbol{q}_{1}=boldsymbol{4} times mathbf{1 0}^{-mathbf{6}} boldsymbol{C} )
and ( q_{2}=9 times 10^{-6} C ) are placed ( 10 mathrm{cm} )
a part in air. The position of a third charge to be placed between them, such that there will be no resultant force on it
is:
A ( .6 mathrm{cm} ) from ( q_{1} )
B. ( 3 mathrm{cm} ) from ( q_{1} )
c. ( 4 mathrm{cm} ) from ( q_{1} )
D. ( 7 mathrm{cm} ) from ( q_{1} )
12
907A charged oil drop od mass ( 2.5 times ) ( 10^{-7} k g ) is in space between the two
plates, each of area ( 2 times 10^{-2} m^{2} ) of a
parallel plate capacitor. When the upper plate has a charge of ( 5 times 10^{-7} C ) and the
lower plate has an equal negative
charge then the oil remains stationery. The charge of the oil drop is (take, ( g= ) ( 10 m / s^{2} )
A ( cdot 9 times 10^{-1} C )
В ( cdot 9 times 10^{-6} C )
C ( .8 .85 times 10^{-13} C )
D. ( 1.8 times 10^{-14} C )
12
spherical shell that has radius ( R_{2} ) and
charge ( Q )
Which of the following changes will
increase the capacitance of the
system?
: Increase the magnitude of the charge,
( Q )
II: Increase ( boldsymbol{R}_{2} ) while leaving ( boldsymbol{R}_{1} ) fixed.
III: Increase ( boldsymbol{R}_{1} ) while leaving ( boldsymbol{R}_{2} ) fixed.
IV: Increase both R1 and R2 while leaving
the difference in radii, ( boldsymbol{R}_{2}-boldsymbol{R}_{1}, ) fixed
A. I only
B. Il only
c. III only
D. III and IV only
12
909The number of electrons to be removed
from a glass rod in order that it acquires a charge of ( 1 mu C ) is:
A. ( 6.25 times 10^{12} )
B. ( 10^{12} )
c. ( 6.25 times 10^{13} )
D. ( 10^{13} )
12
910A body is brought near a negatively charged gold leaf electroscope. If the divergence of leaves remains
unchanged, state the kind of charge on body in this case.
A. positive
B. Negative
c. no charge
D. cant say
12
911Two metallic spheres, one hollow and the other solid, have same diameter.
The hollow sphere will hold charge
A. Same as the solid sphere
B. 2 times as the solid sphere
( mathrm{c} cdot frac{1}{2} ) times as the solid sphere
D. zero
12
912State Gauss law in electrostatics. Using the law derive an expression for electric field due to a uniformly charged thin spherical shell at a point outside the shell.12
913A charge of magnitude ( Q ) is placed at the origin. A second charge of magnitude ( 4 Q ) is placed at the position ( x=d ) along the ( x ) -axis.

Other than infinitely far away, at what position on the ( x ) -axis will a positive test charge experience a zero net force?
A ( . x=-d )
B. ( x=-frac{d}{2} )
c. ( x=frac{d}{3} )
D. ( x=frac{3 d}{2} )
E. At no position other than infinitely far away will the positive test charge experience zero net force

12
914A metal sphere of radius ( r_{1} ) charged to a
potential ( V_{1} ) is then placed in a thin
walled uncharged conducting spherical
shell of radius ( r_{2} . ) Determine the
potential acquired by the spherical
shell after it has been connected for
short time to a sphere by a conductor.
12
915The charge on a sphere of radius ( r ) is ( +Q ) At a point ( P ) which is outside this sphere and at a sufficient distance from it, the
electric field is E. Now, another sphere of radius ( 2 mathrm{r} ) and charge ( -2 mathrm{Q} ) is placed with
( P ) as the centre of this second sphere Then, the electric field at the midpoint
of the line joining the centres of the two spheres is :
A. ( E )
в. ( 4 E )
( c .6 E )
D. ( 12 E )
12
916Four charges are arranged on y-axis as shown in figure. then the electric field at
point ( boldsymbol{P} ) is proportional to:
( A cdot frac{1}{d} )
B. ( frac{1}{d^{2}} )
c. ( frac{1}{d^{4}} )
D.
12
917Two copper balls, each weighting ( 10 g ) are kept in air ( 10 mathrm{cm} ) apart. If one
electron from every ( 10^{6} ) atom is transferred from one ball to the other,
the coulomb force between them is
(atomic weight of copper is 63.5 )
A ( cdot 2 times 10^{10} mathrm{N} )
B ( .2 times 10^{4} mathrm{N} )
( mathbf{c} cdot 2 times 10^{8} mathrm{N} )
D. ( 2 times 10^{6} mathrm{N} )
12
918Compare how the magnitude of the electric field decreases with distance
from a uniform charged sphere and a uniform charged wire.
A. Both decrease with a one over the square of the distance relationship.
B. From the sphere, the electric field decreases with a one over the distance relationship. From the wire, the electric field decreases with a one over the distance squared relationship
c. Both decrease with a one over the distance relationship.
D. From the wire, the electric field decreases with a one over the distance relationship. From the sphere, the electric field decreases with a one over the distance squared relationship
12
919Two identical helium filled balloon ( boldsymbol{A} )
and ( B mathrm{m} ) fastened to a weight of ( 5 g ) by
threads floats in equilibrium as shown
in fig. Calculate the charge on each
balloons, assuming that they carry
equal charges
12
920An electric dipole is placed in nonuniform electric field, then it
experiences
A . only torque
B. force and torque
c. only force
D. neither force nor torque
12
921A charge ( +mathrm{Q} ) is located in space at point ( (x=1 m, y=10 m, z=5 m) . ) What is
the total electric flux that passes
through the ( y-z ) plane?
A ( cdot frac{Q}{varepsilon_{0}} )
в. ( frac{Q}{3 varepsilon_{0}} )
c. ( frac{Q}{6 varepsilon_{0}} )
D. ( frac{Q}{2 varepsilon_{0}} )
12
922羊 里 月 卓12
923Four equal charges, each ( +boldsymbol{q} ) are placed
at the corners of a square of side ( a ). Then
the coulomb force experienced one charge due to the rest of there is:-
( ^{text {A }} cdot frac{q^{2}}{k a^{2}}left[sqrt{2}+frac{1}{2}right] )
B. ( 3 k q^{2} / a^{2} )
C ( cdot 2 sqrt{2} k q^{2} / a^{2} )
D. zero
12
924The charge flowing through a resistance ( R ) varies with time ( t ) as ( Q=a t-b t^{2} )
where a and b are positive constants.
The total heat produced in ( boldsymbol{R} ) is:
A ( cdot frac{a^{3} R}{6 b b} )
B. ( frac{a^{3} R}{3 b} )
c. ( frac{a^{3} R}{2 b} )
D. ( frac{a^{3} R}{b} )
12
925The electric charge developed on glass
rod rubbed with silk cloth is different
from the charge developed on ebonite rod rubbed with fur
A. True
B. False
12
926A surface ( d s=10 hat{j} ) is kept in an electric field ( overrightarrow{boldsymbol{E}}=mathbf{2} hat{boldsymbol{i}}+boldsymbol{4} hat{boldsymbol{j}}+7 hat{boldsymbol{k}} . ) How much
electric flux will come out through the surface?
A . 40 unit
B. 50 unit
c. 30unit
D. 20 unit
12
927Consider a uniform electric field ( boldsymbol{E}= ) ( 3 times 10^{3} hat{i} mathrm{N} / mathrm{C} )
(a) What is the flux of
this field through a square of ( 10 mathrm{cm} ) on a side whose plane is parallel to the ( y z ) plane?
(b) What is the flux through the same square if the normal to its plane
makes a ( 60^{circ} ) angle with the ( x ) -axis?
12
928Which of the following charging methods work without ever touching the object to be charged to the object used to charge it?
A. charging by friction
B. charging by contact
c. charging by induction
D. all of these
12
929When a polythene piece is rubbed with wool, it acquires negative charge.
A. True
B. False
12
930Figure shows the electric field lines
around an electric dipole. Which of the arrows best represents the electric field
at point P?
( A )
3.
( c )
D
12
931The line ( A A^{prime} ) is on a changed infinite conducting plane which is perpendicular to the plane of the paper. The plane has a surface density of
charge ( sigma ) and ( mathrm{B} ) is a ball of mass ( mathrm{m} ) with
a like charge of magnitude ( q . B ) is connected by a string from a point on the line ( A A^{prime} . ) The tangent of the angle ( (theta) ) formed between the line ( A A^{prime} ) and the
string is:
A ( cdot frac{q sigma}{2 epsilon_{c} m g} )
В . ( frac{q sigma}{4 pi epsilon theta} m g )
c. ( frac{q sigma}{2 pi epsilon m g} )
D. ( frac{q sigma}{epsilon_{0} m g} )
12
932An electric dipole has a pair of equa and opposite point charges ( +mathrm{Q} ) and ( mathrm{Q} ) separated by a distance 2x. The axis of the dipole is defined as
A. the line joining positive charge to -ve charge
B. the line making angle of ( 45^{circ} ) with line joining two charges
c. perpendicular to the line joining the two charges drawn at the centre and pointing upward direction
D. perpendicular to the line joining the two charges drawn at the centre and pointing downward direction
12
933An electron enters an electric field with
its velocity in the direction of the electric lines of field then:
A. the path of the electron will be a circle
B. the path of the electron will be a parabola
c. the velocity of the electron will decrease just after entry
D. the velocity of the electron will increase just after entry
12
934respectively, constitute an electric
dipole. Distance ( A B=2 a, 0 ) is the mid point of the dipole and OP is
perpendicular to AB. A charge Q is placed at ( P ) where ( O P=y ) and ( y>>2 a . ) The charge ( Q ) experiences and electrostatic
force F. If ( Q ) is now moved along the
equatorial line to ( P^{prime} ) such that ( O P^{prime}= ) ( left(frac{y}{3}right) ) the force on ( Q ) will be close to ( L ) ( left(frac{y}{3}>>2 aright) )
( A cdot frac{F}{3} )
в. зF
( c . ) 9F
D. 27
12
935If the object is not grounded while performing electrostatic induction, the nearby charge will
A. induce equal and opposite charges in the object.
B. induce equal charges in the object.
c. induce opposite charges in the object
D. None of the above
12
936One-fourth of a sphere of radius R is removed as shown in Fig. An electric field E exists parallel to the xy plane. Find the flux through the remaining curved part :
( mathbf{A} cdot pi R^{2} E )
В. ( sqrt{2} pi R^{2} E )
c. ( pi R^{2} E / sqrt{2} )
D. none of these
12
937A long straight charged wire has the electric field measured as ( 5 N / C ) and
pointing down at a distance of ( 10 mathrm{cm} )
above it.

What would the electric field measure
at ( 10 mathrm{cm} ) below it?
A. ( 10 N / C ) toward the bottom of the screen
B. ( 5 N / C ) toward the bottom of the screenn
c. ( 10 N / C ) toward the top of the screen.
D. ( 5 N / C ) toward the top of the screen

12
938Assertion
Gauss law holds good only to those
closed surfaces which is enclosing non-
zero electric charge.
Reason
The electric flux through a closed surface is unaltered due to the
presence of outside charge.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is incorrect but Reason is correct
D. Both Assertion and Reason are incorrect
12
939Eight small droplets of mercury of equal radii are charged to the same potential ( 10 V ). If they coalesce to form one big drop, the potential on big drop is:
A . ( 10 V )
в. ( 20 V )
( c .30 V )
D. ( 40 V )
12
940Let ( E_{1}(r), E_{2}(r) ) and ( E_{3}(r) ) be the
respective electric fields at a distance from a point charge ( Q, ) an infinitely long wire with constant linear charge density ( lambda, ) and an infinite plane with uniform
surface charge density ( sigma . ) If ( mathrm{E}_{1}left(r_{0}right)= )
( E_{2}left(r_{0}right)=E_{3}left(r_{0}right) ) at a given distance ( r_{0} )
then :
A ( cdot Q=4 sigma pi r_{0}^{2} )
B . ( r_{0}=frac{lambda}{2 pi sigma} )
c. ( E_{1}left(r_{0} / 2right)=2 E_{2}left(r_{0} / 2right) )
D. ( E_{2}left(r_{0} / 2right)=4 E_{3}left(r_{0} / 2right) )
12
941Two equal charges ‘ ( q ) ‘ of opposite sign are separated by a small distance ‘d’. The electric intensity ‘ ( E ) ‘ at a point on the straight line passing through the two charges at a very large distance ‘ ( r ) ‘ from the midpoint of two charges is :
A ( cdot frac{1}{4 pi varepsilon_{0}} frac{q d}{r^{2}} )
В. ( frac{1}{4 pi varepsilon_{0}} frac{2 q d}{r^{2}} )
c. ( frac{1}{4 pi varepsilon_{0}} frac{q d}{r^{3}} )
D. ( frac{1}{4 pi varepsilon_{0}} frac{2 q d}{r^{3}} )
12
942State whether given statement is True or False

Iron is a better conductor of heat than
copper
A. True
B. False

12
943How much time will have elapsed?
A ( .1 .42 times 10^{-8} mathrm{s} )
B . ( 2.84 times 10^{-8} mathrm{s} )
c. ( 3.84 times 10^{-8} mathrm{s} )
D. ( 5.68 times 10^{-8} mathrm{s} )
12
944Choose the appropriate option:
In metals. than the insulators.
A. There are more free electrons
B. There are less free electrons
c. There are all free electrons
D. There are no free electrons
12
945State Gauss’s law in electrostatics.12
946An electric dipole (dipole moment ( =p ) )
is placed in a uniform electric field in
stable equilibrium position at rest. Now it is rotated by a small angle and released. The time after which it comes
to the equilibrium position again (for first time) is ( t . ) Then the moment of
inertia of the dipole about the axis of
rotation is :
A ( cdot frac{4 t^{2} p E}{3 pi^{2}} )
в. ( frac{1 t^{2} p E}{4 pi^{2}} )
c. ( frac{2 t^{2} p E}{3 pi^{2}} )
D. ( _{4} frac{t^{2} p E}{pi^{2}} )
12
947A negatively charged ebonite rod is brought near the glass rod which has been robbed on silk. State your
observation between them
A . Attraction
B. Repulsion
c. No change
D. cant say
12
948If one penetrates a uniformly charged solid sphere, the electric field ( E )
A . increases
B. decreases
c. is zero at all points
D. remains same as at the surface
12
949( A, B ) and ( C ) are three charged bodies. If ( A )
and B repel each other and A attracts C, what is the nature of the force between
B and C?
12
950The number of electrons for one
coulomb of charge are:
A ( cdot 6.25 times 10^{23} )
B. ( 6.25 times 10^{21} )
c. ( 6.25 times 10^{18} )
D. ( 6.25 times 10^{19} )
12
951When two charged objects attract each other, the objects carry:
A. same charges
B. opposite charges
c. no charges
D. none of the above
12
952Assertion
Charge can neither be created nor
destroyed.
Reason
Positive Charge attracts negative
charge.
A. Both Assertion and Reason are correct and Reason is
the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
953Three infinite planes have a uniform
surface charge density ( sigma ) on is surface.
All charges are fixed.On each of the
three infinite planes parallel to the ( y- )
( z ) plane placed at ( x=-a, x=0 ) and
( boldsymbol{x}=boldsymbol{a} . ) The potential difference between
( A ) and ( C ) is:
( A )
в. ( frac{sigma}{varepsilon_{0}} )
c. ( frac{sigma a}{2 varepsilon_{0}} )
D.
12
954An uncharged metal object ( M ) is
insulated from its surroundings. A
positively charged metal sphere ( boldsymbol{S} ) is
then brought near to ( M . ) Which diagram
best illustrated the resultant
distributions of charge on ( S ) and ( M ? )
( A )
в.
( c )
D.
12
955Four point charges, each equal to ( q=4 mu C )
are held at the corners of a square ABCD of side ( a=10 mathrm{cm} . ) Find the magnitude and sign of a charge ( Q ) placed at the centers of the square so that the system of charges is in equilibrium.
12
956A particle with charge ( e ) and mass ( m ) moving along the X-axis with a uniform speed ( u ), enters a region where a
uniform electric field ( E ) is acting along
the Y-axis. The particle starts to move in a parabola. Its focal length (neglecting any effect of gravity) is :
( ^{A} cdot frac{2 m u^{2}}{e E} )
в. ( frac{e E}{2 m u^{2}} )
c. ( frac{m u}{2 E} )
D. ( frac{m u^{2}}{2 e E} )
12
957What is the electric potential at the centre of a hemisphere of radius ( mathrm{R} ) and
having surface charge density ( sigma ? )
A ( cdot frac{sigma}{2 varepsilon_{0}} )
в. ( frac{sigma}{varepsilon_{0}} )
c. ( frac{sigma}{varepsilon_{0}} R )
D. ( frac{sigma}{2 varepsilon_{0}} R )
12
958A charge ( q ) is placed at 0 in the cavity in a spherical uncharged conductor, Point S is outside the conductor. If q is
displaced from 0 towards ( S ) (still
remaining within the cavity)
A . electric field at S will increase
B. electric field at S will decrease
c. electric field at ( S ) will first increase and then decreas
D. electric field at S will not change
12
959Assertion
Electric filed of a dipole can’t be found using only Gauss law. (i.e. without using superposition principle)
Reason
Gauss law is valid only for symmetrical charge distribution
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason is correct
12
960Electric flux per unit solid angle is defined as
A. Electric force
B. Electric field intensity
c. Electric potential
D. Electric power
12
961Two identical metal spheres ( A ) and ( B )
placed in contact are supported on insulating stand. What kind of charge will ( A ) and ( B ) develop when a negatively
charged ebonite rod is brought near ( A ) ?
12
962A hollow cylinder has a charge ( q )
coulomb within it. If ( phi ) is the electric flux in units of volt-meter associated
with the curved surface ( mathrm{B} ), the flux
linked with the plane surface A in units of volt-meter will be?
12
963If ( E_{a} ) be the electric field intensity due to a short dipole at a point on the axis
and ( E_{r} ) be that on the right bisector at the same distance from the dipole, then
A ( cdot E_{a}=E_{r} )
В. ( E_{a}=2 E_{r} )
( mathbf{c} cdot E_{r}=2 E_{a} )
D. ( E_{a}=sqrt{2} E_{r} )
12
964Two free charges ( q ) and ( 4 q ) are placed at a distance d apart. A third charge ( Q ) is placed between them at a distance ( x ) from charges q such that the system is in equilibrium.Then
( A cdot Q=frac{4 q}{9} )
B . ( Q=frac{7 q}{9} )
c. ( Q=-frac{3 q}{9} )
D ( cdot Q=-frac{2 q}{9} )
12
965Let ( A B C ) is a right angled triangle in which ( A B=3 mathrm{cm} ) and ( mathrm{BC}=4 mathrm{cm} ) and
( angle A B C=90^{circ} . ) The three charges +15,+12
and -20 esu are placed on A, B and C respectively. The force acting on B will be
A. zero
B. 25 dyne
c. 30 dyne
D. 150 dyne
12
966Two charges each of ( +Q ) units are
placed along a line. A third charge ( -q ) is
placed between them. At what position and for what value of ( q, ) will the system be in equilibrium?
12
967A cylinder of radius ( R ) and length Lis placed in the uniform electric field ( mathrm{E} ) parallel to the cylinder axis. The total flux from the curved surface of the cylinder is
given by :
A ( cdot 2 pi R^{2} E )
в. ( frac{pi R^{2}}{E} )
c. ( frac{pi R^{2}-pi R}{E} )
D. zero
12
968Find the charge enclosed in the cylinder
A ( cdot 1.1 times 10^{-6} )
В. ( 1.1 times 10^{-9} )
c. ( 1.1 times 10^{-11} )
D. ( 1.1 times 10^{-12} )
12
969Which one of the following is bad conductor of electricity?
A. Acid
B. coal
c. Distilled water
D. Human body
12
970( frac{k}{k} )12
971Explain working of electroscopes?12
972If ( vec{E}_{a x} ) and ( vec{E}_{e q} ) represents electric field at a point on the axial and equatorial line of a dipole. If points are at a distance ( r ) from the centre of the dipole,
for ( boldsymbol{r} gg boldsymbol{a} )
( mathbf{A} cdot overrightarrow{E_{a x}}=overrightarrow{E_{e q}} )
B . ( overrightarrow{E_{a x}}=-overrightarrow{E_{e q}} )
c. ( overrightarrow{E_{a x}}=-2 overrightarrow{E_{e q}} )
D. ( overrightarrow{E_{e q}}=2 overrightarrow{E_{a x}} )
12
973Two charges ( +q ) and ( -q ) are placed at a distance a in a uniform electric field.
The dipole moment of the combination is ( 2 q a(cos theta hat{i}+sin theta hat{j}), ) where, ( theta ) is the
angle between the direction of the field and the line joining the charges. Which of the following statement(s) is are correct?
This question has multiple correct options
A. The torque exerted by the field on the dipole vanishes
B. The net force on the dipole vanishes
c. The torque is independent of the choice of coordinates
D. The net force is independent of a
12
974The surface area of the drop is:
Spherical drop
( mathbf{A} cdot 4 pi R^{2} )
( mathbf{B} cdot 4 pileft(9 t^{2} R^{4}right)^{1 / 3} )
( mathbf{C} cdot 4 pileft(9 t^{4} R^{2}right)^{1 / 3} )
D. ( 4 pi R(t+R) )
12
975Which is the biggest physical quantity?
A. A coulomb
B. Charge on an electron
c. charge on a proton
D. Charge on a neutron
12
976Assertion
STATEMENT-1: In a region where uniform electric field exists, the net
charge within volume of any size is zero.
Reason

STATEMENT-2: The electric flux within
any closed surface in a region of uniform electric field is zero.
A. Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-
B. Statement-1 is True, Statement-2 is True; Statement-2 is NOT a correct explanation for Statement-
c. statement- – is True, Statement-2 is False
D. Statement-1 is False, Statement-2 is True

12
977Flux through the rectangular piece of area ( 10 mathrm{cm} ) by ( 20 mathrm{cm} ) when placed ( (mathrm{as} ) shown in an uniform electric field of
( 200 mathrm{N} / mathrm{C}, ) ) is
A ( cdot ) 4.0 ( N m^{2} / C )
B . 3.5 ( N m^{2} / C )
c. ( 2.5 mathrm{Nm}^{2} / mathrm{C} )
D. zer
12
978A conducting hollow sphere of radius
( 0.1 mathrm{m} ) is given a charge of ( 10 mu C . ) The
electric potential on the surface of
sphere will be :
A . zero
B . ( 3 times 10^{5} V )
( mathbf{c} cdot 9 times 10^{5} V )
( mathbf{D} cdot 9 times 10^{9} V )
12
979electric field is along negative ( x ) direction and it is constant. A particle having mass ( m ) and charge ( q ) is projected along ( x ) -direction with speed ( V_{0} . ) An additional force ( overrightarrow{boldsymbol{F}}=overrightarrow{boldsymbol{C}} times overrightarrow{boldsymbol{V}} ) is
acting on the charge where ( vec{V} ) is velocity vector and ( vec{C} ) is a constant vector. The
charge comes out of region with speed ( boldsymbol{V}_{0} )
( 2^{text {as shown in figure, then the }} )
magnitude of electric field is :
A ( cdot frac{3}{8} frac{m V_{0}^{2}}{q d} )
B. ( frac{4}{3} frac{m V_{0}^{2}}{q d} )
c. ( frac{8}{3} frac{m V_{0}^{2}}{q d} )
D. Can’t be determined
12
980Find the electric flux crossing the wire frame ( A B C D ) of length ( I, ) width ( b, ) and
center at a distance ( 0 P=d ) from an
infinite line of charge with linear charge
density ( lambda ). Consider that the plane of the
frame is perpendicular to the line OP
Fig.
A ( cdot frac{2 N}{pi varepsilon_{0}} tan ^{-1}left(frac{b}{2 d}right) )
B. ( frac{N}{pi varepsilon_{0}} tan ^{-1}left(frac{b}{2 d}right) )
c. ( frac{3 N}{pi varepsilon_{0}} tan ^{-1}left(frac{7 b}{2 d}right) )
D. ( frac{N}{2 pi varepsilon_{0}} tan ^{-1}left(frac{b}{2 d}right) )
12
981If an electric field is given by ( 10 hat{i}+ ) ( mathbf{3} hat{boldsymbol{j}}+mathbf{4} hat{boldsymbol{k}}, ) calculate the electric flux
through a surface of area 10 units lying in ( boldsymbol{y} boldsymbol{z} ) plane
12
982Two particles of masses ( m ) and ( 2 m )
having same charges ( q ) each, are placed
in a uniform electric field ( boldsymbol{E} ) and allowed
to move for the same time. Find the
ratio of their kinetic energies:
12
983Two point charges ( (+e) ) and ( (-e) ) are
kept inside a large metallic cube without touching its sides. Electric flux emerging out of the cube is?
A ( cdot e / varepsilon_{0} )
В. – ( -e / varepsilon_{0} )
c. zero
D. ( 2 e / varepsilon_{0} )
12
984Which of the following is an electrica conductor?
A. Silver
B. Rubber Cork
c. Silver-coloured plastic sheet
D. woodd
12
985A disk with
radius R has uniform surface cha
disk as a sereis of thin concer
potential ( V ) at a point on the di the disk.Assume that the potent
A ( cdot frac{sigma}{2 varepsilon_{0}} )
B ( cdot frac{sigma}{30} )
( c cdot frac{sigma R}{24 c-c} )
D. ( frac{sigma}{66} )
12
986State whether true or false.
Pure water is a good conductor of electricity.
A. True
B. False
12
987The length of half wave dipole at ( 15 mathrm{MHz} ) is?
( mathbf{A} cdot 15 mathrm{cm} )
B. ( 12 mathrm{cm} )
c. ( 10 mathrm{cm} )
D. None of these
12
988The cube as shown in Fig. has sides of
length ( L=10.0 mathrm{cm} . ) The electric field is
uniform, has a magnitude ( boldsymbol{E}=mathbf{4 . 0 0} times )
( 10^{3} N C^{-1}, ) and is parallel to the ( x y- )
plane at an angle of ( 37^{circ} ) measured from
the ( +x-a x i s ) towards the ( +y-a x i s )
The total net electric flux through all faces of the cube is
( mathbf{A} cdot 8 N m^{2} C^{-1} )
B. ( -8 N m^{2} C^{-1} )
( mathbf{c} cdot 24 N m^{2} C^{-1} )
D. zero
12
989What is meant by electric flux? Write its
S.I. unit and dimensional formula.
12
990Total normal electric field =
( mathbf{A} cdot epsilon_{0} vec{E} cdot overrightarrow{d S} )
в. ( vec{E} cdot overrightarrow{d S} )
( mathbf{c} cdot epsilon_{0} vec{E} )
D. ( epsilon_{0} overline{d S} )
12
991An electric dipole coincides on the zaxis and its centre coincides with the origin of the cartesian coordinate system. The electric field at an axial
point at a distance ( z ) from the origin is
( E(z) ) and the electric field at an
equatorial point at a distance ( y ) from
the origin is ( E(y) )

Given that ( y=z>>a ), the value of
( frac{E(z)}{E(y)} ) is
A . 1
B. 2
( c .4 )
D. 3

12
992An electron is moving round the nucleus of a hydrogen atom in a circular orbit of radius r. The coulomb
force ( vec{F} ) between the two is –
( ^{A} cdot_{K} frac{e^{2}}{r^{2}} )
в. ( -K frac{e^{2}}{r^{3}} )
c. ( _{K} frac{e^{2}}{r^{3}} vec{r} )
D. ( -K frac{e^{2}}{r^{2}} )
12
993Two isolated, charged conducting spheres of radii a and b produce the same electric field near their surfaces.
The ratio of electric potentials on their
surfaces is :
A ( cdot frac{a}{b} )
B. ( frac{b}{a} )
c. ( frac{a^{2}}{b^{2}} )
D. ( frac{b^{2}}{a^{2}} )
12
994Electric field at point ( boldsymbol{A} ) depends on
( A )
в. ( q_{2} )
( c cdot ) both ( q_{1} ) and ( q_{2} )
D. None of these
12
995An uncharged insulator can be charged by with another suitable body
A. diverging
B. induction
c. rubbing
D. excess
12
996For a given surface the Gauss’s law is stated as ( int E cdot d s=0 . ) From this we can conclude that:
A. ( E ) is necessarily zero on the surface
B. ( E ) is perpendicular to the surface at every point
c. the total flux through the surface is zero
D. the flux is only going out of the surface
12
997Two identical ( +v e ) charges are at the ends of a straight line AB. Another identical ( +v e ) charge is placed at ‘C’ such that
( A B=B C . ) (A, B and C being on the same
line). Now the force on ‘A’ will :
( A ). increase
B. decrease
c. remain same
D. cannot be predicted
12
998The potential energy of the dipole in the equilibrium position is :
( mathbf{A} cdot+3 times 10^{-23} J )
В. ( -3 times 10^{-23} mathrm{J} )
c. ( -6 times 10^{-23} J )
D. ( -3 times 10^{-36} J )
12
999The process of charging a conductor from a charged body without touching them together is called induction
A. True
B. False
c. Ambiguous
D. Data insufficient
12
1000Match the following and choose the
begin{tabular}{lll|l}
& Table ( mathbf{A} ) & & Table ( mathbf{B} ) \
a. & conductor & 1. & plastic \
b. & charge at rest & 2. & current electricity \
c. & moving charge & 3. & electrostatic \
d. & insulator & 4. & copper
end{tabular}
( mathbf{A} )
( c-1, d-2, b-3, a-4 )
B . ( d-1, c-2, a-3, b-4 )
c. ( c-4, d-2, b-3, a-1 )
D. ( d-1, c-2, b-3, a-4 )
12
1001The instrument which can be used to
detect a charged body is :
A. Electroplate
B. Leaf electroscope
c. Capacitor
D. Galvanometer
12
1002A point charge ( +Q ) fixed in position, as shown in the diagram. Five points near
the charge and in the plane of the page are shown.
At which point will an electron experience a force directed toward the
top of the page?
( A cdot A )
B. B
( c cdot c )
D.
( E . E )
12
1003Electric charge can not flow through
A. insulators
B. conductors
c. both insulators and conductors
D. neither insulators nor conductors
12
1004The electricity developed on objects, when they are rubbed with each other is
called:
A. Frictional potential
B. Frictional electricity
c. Static electricity
D. Static potential
12
1005(a) Show that the normal component of
electrostatic field has a discontinuity
from one side of a charged surface to another given by ( \$ \$left(E_{-} 21,-right. )
( mathrm{~ I f r a c { s i g m a ~ } { v a r e p s i l o n ~} )
( 03 \$ \$ )
where ( hat{n} ) is a unit vector normal to the
surface at a point and ( sigma ) is the surface
charge density at that point. (The
direction of ( hat{n} text { is from side } 1 text { to side } 2 .) )
Hence show that just outside
a conductor, the electric field is ( sigma hat{n} / epsilon_{0} )
(b) Show that the tangential component of electrostatic field is continuous from
one side of a charged surface to another. [Hint: For (a), use Gauss’s law. For, (b) use the fact that work done by
electrostatic field on a closed loop is zero.]
12
1006The ratio of the electric force between
two proton to that between two
electrons under similar conditions is
the order of:
( mathbf{A} cdot 10^{4} )
B. ( 10^{3} )
( c cdot 10^{36} )
D.
12
1007Two conducting charged spheres ( X ) and
( Y ) having unequal charges are connected by the wire. Which of the following is true?
A. Charge is conserved
B. Electrostatic energy is conserved
c. Both the charge and electrostatic energy is conserved
D. Neither of these is conserved
12
1008The electric dipole is placed along the ( x )
axis at the origin ( O . A ) point ( P ) is at a
distance of ( 20 mathrm{cm} ) from this origin such
that ( O P ) makes an angle ( 60^{circ} ) with the ( x )
axis. If the electric field at ( P ) makes an
angle ( theta ) with the ( x ) -axis, the value of ( theta )
would be
A ( cdot frac{pi}{3} )
B. ( tan ^{-1} frac{sqrt{3}}{2} )
c. ( frac{2 pi}{3} )
D. ( frac{pi}{3}+tan ^{-1} frac{sqrt{3}}{2} )
12
1009An electric dipole is placed in a non
uniform electric field increasing along the
( + )ve direction of ( mathrm{X} ) – axis. The dipole
moves along and rotates
A. ( +v e ) direction of ( X ) – axis, clockwise
B. – ve direction of ( X ) – axis, clockwise
c. ( +v e ) direction of ( X ) – axis, anti clockwise
D. – ve direction of ( X ) – axis, anti clockwise
12
1010In electric dipole what is the locus of Zero potential?12
1011Calculate the total positive or negative
charge on a ( 3.11 g ) copper penny. Given
Avogadro number ( =6.02 times 10^{23} )
atomic number of copper ( =29 ) and
atomic mass of copper ( =mathbf{6 3 . 5} )
A ( cdot 3.37 times 10^{5} mathrm{C} )
B . ( 2.37 times 10^{5} mathrm{C} )
c. ( 1.37 times 10^{5} C )
D. ( 0.37 times 10^{5} C )
12
1012A spherical metal shell ( A ) of radius ( R_{A} )
and a solid metal sphere ( B ) of radius
( R_{8}left(Q_{B} )
c. ( frac{sigma_{A}}{sigma_{B}}=frac{R_{B}}{R_{A}} )
D. ( E_{A}^{text {on surface}}<E_{B^{text {B }}}^{text {snj }} )
12
1013A copper rod ( A B ) of length ( l ) is rotated about end A with a constant angular
velocity ( omega . ) Find electric field at a
distance ( x ) from the axis of rotation:
A ( cdot frac{m omega^{2} x}{e} )
B. ( frac{m omega x}{e l} )
c. ( frac{m x}{omega^{2} l} )
D. ( frac{m e}{omega^{2} x} )
12
1014State whether true or false.
Metals as compared to non-metals are generally bad conductors of electricity.
A. True
B. False
12
1015When a body is charged by induction, then the body
A. Becomes neutral
B. Does not lose any charge
12
1016Dimensional formula for electric field is
A ( cdotleft[M L^{2} T^{-3} A^{-1}right] )
B ( cdotleft[M L^{2} T^{-3} A^{-2}right] )
( mathbf{c} cdotleft[M L T^{-3} A^{-1}right] )
D cdot ( left[M^{0} L^{0} T^{0} A^{0}right] )
12
1017The distance between electron and
proton in the H-atom is about 5.3
( times 10^{-11} ) metre. What is the magnitude
of electric force between these two
particles? ( left(frac{1}{4 pi varepsilon_{0}}=9 times 10^{9} frac{N m^{2}}{C^{2}}right) )
12
1018Two point charges of charge values ( Q ) and ( q ) are placed at a distance of ( x ) and ( x / 2 ) respectively from a third charge of
charge value ( 4 q, ) all charges being in
the same straight line. Calculate the
magnitude and nature of charge ( Q ) such that the net force experienced by the charge ( q ) is zero. (Assume q is located between charges ( 4 q text { and } Q) )
12
1019A gold leaf electroscope is given a positive charge so that its leaves diverge. How is the divergence of leaves affected, when a positively charged rod is brought near its disc?
A. Divergence increases
B. Divergence decreases
c. Divergence remains same
D. can’t say
12
1020If ( vec{p}_{2} ) is free to rotate about an axis,
perpendicular to the plane and passing
through ( A, ) the angle between ( vec{p}_{2} ) and ( vec{p}_{1} )
will be :
A ( cdot sin ^{-1}left(frac{1}{3}right) )
( B cdot tan ^{-1}(3) )
( mathbf{c} cdot cos ^{-1}left(frac{1}{3}right) )
( D cdot cot ^{-1}(3) )
12
1021The dipolemoment of the given system is:
A. ( sqrt{3} q l ) along perpendicular bisector of ( q-q ) line
B. ( 2 q l ) along perpendicular bisector of ( q-q ) line
C ( cdot q l sqrt{2} ) along perpendicular bisector of ( q-q ) line
D. 0
12
1022Two concentric conducting thin spherical shells have radii a and b ( (a< )
b). If they are charged to ( +Q ) and ( -2 Q ) the graph of electric field as a function of
the distance r from center is:
A.
B.
( c )
D.
12
1023Two conductors are of same shape and
size. One of copper and the other of aluminium (less conducting) are placed in an uniform electric field. The charge induced in alumintum
A. Will be less than that in copper
B. will be more than that in copper
c. will be equal to that in copper
D. cannot be compared with that of copper
12
1024An electric dipole moment ( vec{p}=(2.0 hat{i}+ ) ( mathbf{3} .0 hat{boldsymbol{j}}) mu C . mathrm{m} ) is placed in a uniform
electric field ( overrightarrow{boldsymbol{E}}=(boldsymbol{3} cdot boldsymbol{0} hat{boldsymbol{i}}+boldsymbol{2} cdot boldsymbol{0} widehat{boldsymbol{k}}) times )
( mathbf{1 0}^{mathbf{5}} mathbf{N} boldsymbol{C}^{-mathbf{1}} )
This question has multiple correct options
A. The torque that ( vec{E} ) exerts on ( vec{p} ) is ( (0.6 vec{i}-0.4 vec{j}- ) ( 0.9 vec{k}) N m )
B. The potential energy of the dipole is ( -0.6 J )
C. The potential energy of the dipole is ( 0.6 J ).
D. If the dipole is rotated in the electric field, the maximum potential energy of the dipole is ( 1.3 J )
12
1025Which of the following materials has a negative temperature coefficient of resistance?
A. copper
B. Aluminium
c. carbon
D. brass
12
1026A point charge q is kept on the vertex of the cone of base radius ( r ) and height ( r )
The electric flux through the curved surface will be
( ^{A} cdot frac{q}{2 varepsilon_{0}}left(1-frac{1}{sqrt{2}}right) )
В ( cdot frac{q}{varepsilon_{0}}left(frac{1}{2 sqrt{2}}right) )
( c . ) zer
D. ( frac{q}{varepsilon_{0} sqrt{2}} )
12
1027An electric dipole consists of two opposite charges each of magnitude
( 1.6 times 10^{-19} ) coulomb at separation
1 Armstrong. The diploe moment is:
A ( cdot 1.6 times 10^{-19} c-m )
В. ( 1.6 times 10^{-29} c-m )
c. ( 3.2 times 10^{-29} c-m )
D. ( 3.2 times 10^{-19} mathrm{C}-mathrm{m} )
12
1028On rubbing a glass rod with silk cloth,
( 6.84 times 10^{16} ) electrons are transferred
from glass rod to silk cloth. Find the total charge transferred.
12
1029A neutral water molecules ( left(H_{2} Oright) ) in its
vapour state has an electric dipole moment of ( 6 times 10^{-30} mathrm{Cm} . ) If the
molecule is placed in an electric field of ( 1.5 times 10^{4} N C^{-1}, ) the maximum torque
that the field can exert on it is nearly:
A ( .4 .5 times 10^{-26} mathrm{Nm} )
B. ( 4 times 10^{-34} mathrm{Nm} )
c. ( 9 times 10^{-26} mathrm{Nm} )
D. ( 6 times 10^{-26} mathrm{Nm} )
12
1030State whether true or false.
Copper is a poor conductor of electricity as compared to glass.
A. True
B. False
12
1031A piece of paper appears to be attracted
to a charged ebonite rod, even before
they touch (see fig.). The charge at B is:
A. positive
B. may be positive or negative
c. no charge
D. negative
12
1032A certain charge ( Q ) is divide at first into
two parts ( (q) ) and ( (Q-q) . ) Later on the
charges are placed at a certain
distance. If the force of interaction
between the two charges is maximum
then:
A ( cdot(Q / q)=(4 / 1) )
B cdot ( (Q / q)=(2 / 1) )
c. ( (Q / q)=(3 / 1) )
D・ ( (Q / q)=(5 / 1) )
12
1033A point charge ( +Q ) having mass ( m ) is fixed on horizontal smooth surface.
Another point charge having magnitude ( +2 Q & ) mass ( 2 m ) is projected horizontally towards the charge ( +mathrm{Q} ) from the distance with velocity ( V_{0} ) Force applied by floor on the fixed charge in horizontal direction, when distance between charges becomes ‘d’
A ( cdot frac{2 K Q^{2}}{d^{2}} )
B. ( frac{K Q^{2}}{d^{2}} )
c. zero
D. none
12
1034A hollow half cylinder surface of radius R and length I is placed in a uniform electric field ( vec{E} ). Electric field is acting
perpendicular on the ABCD. If the flux through the curved surface of the hollow
cylindrical surface is ( boldsymbol{E} times boldsymbol{X} boldsymbol{R} boldsymbol{l} ). Find ( mathbf{X} ) ?
12
1035Consider two statements:
A) The force with which two charges
interact is not changed by the presence of the other charges.
B) Electric force experienced by the
charge particle due to number of fixed point charges is vector resultant of the
forces experience due to individual
charge.
( A ). Both ( A ) and ( B ) are correct
B. Only A is correct
C. Only B is correct
D. Both A and B are wrong
12
1036Derive an expression for electric field intensity due to an electric dipole at a point on its axial line.12
1037A long charged cylinder of linear charged density ( lambda ) is surrounded by a hollow co-axial conducting cylinder. What is the electric field in the space
between the two cylinders?
12
1038An electric dipole consists of two
oppositecharges of magnitude ( 1 mu mathrm{C} )
separated by a distanceof 2cm. The dipole is placed in an electric filed
( 10^{-5} mathrm{Vm}^{-1} . ) The maximum torque does
the field exerton the dipole is
( mathbf{A} cdot 10^{-3} mathrm{Nm} )
В. ( 2 times 10^{-13} mathrm{Nm} )
c. ( 3 times 10^{-13} mathrm{Nm} )
D. ( 4 times 10^{-13} mathrm{Nm} )
12
1039The electric field intensity at ( boldsymbol{P} ) and ( boldsymbol{Q} )
in the shown arrangement:
12
1040The acceleration of a charged particle in a uniform electric field is : (where specific
charge of a particle ( left.=frac{q}{m}right) )
A. proportional to its charge only
B. inversely proportional to its mass only
C. proportional to its specific charge
D. inversely proportional to specific charge
12
1041A balloon gets negatively charged by rubbing ceilings of a wall.
A. The balloon sticks to the ceiling forever.
B. The balloon eventually fall off the ceiling
C. The balloon does not stick to the ceiling at all
D. The balloon charges the ceiling negatively
12
1042The ratio of electric force between two
electrons to that between two protons
separated by the same distance in air is
A ( cdot 10^{circ} )
B. ( 10^{6} )
( c cdot 10^{4} )
D. None of the above
12
1043R with centre at the origin, carrying
uniform positive surface charge
density. The variation of the magnitude of the electric field ( |vec{E}(r)| ) and the
electric potential ( V(r) ) with the distance
from the centre, is best represented by
which graph?
( A )
B.
( c )
D.
12
1044toppr
‘8
center of the sphere according to the equation ( =C r . ) The diagram also shows
the cross-section of a Gaussian sphere
of radius ( a ) that is concentric with the
charged sphere

Which of the following expresses the
charge enclosed in the Gaussian
sphere?
( ^{mathrm{A}} cdot frac{2}{3}^{pi} C a^{3} )
в ( cdot frac{4}{3} pi C a^{4} )
c ( cdot frac{1}{4} pi C a^{4} )
D ( cdot pi C a^{4} )
E ( frac{4}{15} pi C a )

12
1045Ten charges having charge ( mathbf{1} mu C, 8 mu C, 27 mu C, dots dots 1000 mu C ) are
placed on the ( x ) -axis with co-ordinates ( boldsymbol{x}=mathbf{1} boldsymbol{m}, mathbf{2} boldsymbol{m}, mathbf{3} boldsymbol{m}, mathbf{4} boldsymbol{m}, dots . . mathbf{1 0} boldsymbol{m} . ) The
net electric field intensity at the origin is:
A ( cdot 9 times 10^{5} N / C )
в. ( 9 times 10^{4} N / C )
C ( .4 .95 times 10^{-5} mathrm{N} / mathrm{C} )
D. ( 4.95 times 10^{5} N / C )
12
1046A charge ( Q ) is distributed over two
concentric hollow spheres of radii ( a ) and ( b(a>b), ) so that the surface charge
densities are equal. The potential at the common centre is ( frac{1}{4 pi epsilon_{0}} ) times
A ( cdot k Qleft(frac{a+b}{a^{2}+b^{2}}right) )
в. ( 2 Qleft(frac{a+b}{a^{2}+b^{2}}right) )
( c cdot Q )
D. ( frac{Q}{2}left(frac{a+b}{a^{2}+b^{2}}right) )
E ( cdot frac{Q}{4}left(frac{a+b}{a^{2}+b^{2}}right) )
12
1047Consider two points 1 and 2 in a region outside a charged sphere. Two points are not vary far away from the sphere. If ( boldsymbol{E} ) and ( boldsymbol{V} ) represent the electric field vector and the electric potential, which of the following is not possible?
A ( cdotleft|vec{E}_{1}right|=left|vec{E}_{2}right|, V_{1}=V_{2} )
в. ( left|vec{E}_{1}right| neqleft|vec{E}_{2}right|, V_{1} neq V_{2} )
c ( cdotleft|vec{E}_{1}right| neqleft|vec{E}_{2}right|, V_{1}=V_{2} )
D . ( left|vec{E}_{1}right|=left|vec{E}_{2}right|, V_{1} neq V_{2} )
12
1048An electron is released from rest in a
uniform electric field which causes it to
accelerate toward the top of the screen
What is the direction of the electric
field?
A. To the left
B. Toward the top of the screen
c. To the right
D. Toward the bottom of the screen
12
1049Which of the following is best insulator?
A. carbon
B. paper
c. ebonite
D. graphite
12
1050Electric field strength due to a point charge of ( 5 mu C ) at a distance of ( 80 mathrm{cm} ) front he charge is
A ( cdot 8 times 10^{4} N / C )
в. ( 7 times 10^{4} mathrm{N} / mathrm{C} )
C ( .5 .55 times 10^{4} N / C )
D. ( 4 times 10^{4} N / C )
12
1051In a region where intensity of electric field is ( 5 N C^{-1}, 40 ) lines of electric force are
crossing per square metre. The number of lines crossing per square metre where
intensity of electric field is ( 10 N C^{-1} ) will
be:
A . 20
B. 80
c. 100
D. 200
12
1052A laser beam of pulse power ( 10^{12} W ) is
focussed on an object of area ( 10^{-4} mathrm{cm}^{2} )
The energy flux in ( W / c m^{2} ) at the point of focus is
A ( cdot 10^{4} )
B. ( 10^{8} )
( mathbf{c} cdot 10^{16} )
D. ( 10^{20} )
12
1053Two positive point charges of unequal magnitude are placed at a certain distance apart. A samll positive test charge is placed at null point, then:
A. Charge is in equilibrium.
B. A test charge is in stable equilibrium
c. The test charge is in neutral equilibrium
D. The test charge is in unstable equilibrium
12
1054The force between two charges in different media are different because.
B. Different media have different viscosities
c. Different media have different densities
D. Different media have different permeabilities
12
1055How many electrons should be removed
from a coin of mas ( 1.6 mathrm{g} ), so that it may
float in an electric field of intensity ( 10^{9} ) N/C directed upward?
A ( .9 .8 times 10^{7} )
B . ( 9.8 times 10^{5} )
( mathbf{c} cdot 9.8 times 10^{3} )
D. ( 9.8 times 10^{1} )
12
1056A redistribution of electrical charge in an object, caused by the influence of nearby charges is termed as
A. electric conduction
B. ionisation
c. electrostatic induction
D. electromagnetic induction
12
1057The parallel plate capacitors with different distance between the plates
are connected in parallel to voltage
source as shown in the figure. A point
positive charge is moved from a point
that is exactly in the middle between
the plates of the capacitor ( c_{1} ) to a point
2 in capacitor ( c_{2} ) that lies at the plates
of ( c_{1} ). Then the work done by the electric
force is.
A. positive
B. negative
c. zero
D. data insufficient.
12
1058A conic surface is placed in a uniform electric field ( E ) as shown in Fig. such
that the field is perpendicular to the
surface on the side ( A B ). The base of the
cone is of radius ( R, ) and the height of the
cone is h. The angle of the cone is ( theta ). Find
the magnitude of the flux that enters
the cone’s curved surface from the left
side. Do not count the outgoing flux
( left(theta<45^{circ}right) )
A ( . E R[h cos theta+pi(R / 2) sin theta )
B. ( E R[h sin theta+pi R / 2 cos theta] )
c. ( E R[h cos theta+pi R sin theta )
D. none of these
12
1059A charge of ( 4 times 10^{-8} C ) is uniformly
distributed over the surface of sphere of
radius ( 1 mathrm{cm} . ) Another hollow sphere of
radius ( 5 mathrm{cm} ) is concentric with the
smaller sphere. Find the intensity of the
electric field ( left(text { in } N C^{-1}right) ) at a distance
( 2 c m ) from the centre. ( k=9 times 10^{-9} S I )
12
1060A Force ( F ) is put on a test charge ( Q ) by an electric field. What is the strength of the electric field at that location?
A ( cdot frac{Q}{F} )
в. ( frac{F}{Q} )
c. ( F Q )
D. ( F Q^{2} )
12
1061Electric field outside a long wire carrying charge q is proportional to:
A ( cdot frac{1}{r} )
в. ( frac{1}{r^{2}} )
c. ( frac{1}{r^{frac{1}{35}}} )
D. ( frac{1}{r^{frac{1}{32}}} )
12
1062When two objects are rubbed against
each other they
A. will loose electrons
B. will repel electrons
c. will attracts each other
D. may attract or repel each other
12
1063A radioactive material is in the form of
a sphere whose radius is ( 9 times 10^{-3} ) m. If
( 6.25 times 10^{12} beta^{-} ) particles are emitted per
second by it then in how much time will a potential of 1 volt be produced on the
sphere if it is isolated?
A . ( 1.1 mathrm{ms} )
B . ( 10^{-8} mathrm{ms} )
c. ( 1.0 mu s )
D. 11 mus
12
1064Assertion
The flux of electric field through a spherical surface of radius 1.5 a is more
than flux of electric field through a
spherical surface of radius 0.5 a. (Both
centred at origin)
Reason
The electric field at ( x=1.5 ) a is more than
electric field at 0.5 a
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason is correct
12
1065When an electron moves in a circular
path around a stationary nucleus
charge at the center:

This question has multiple correct options
A. the acceleration of the electron changes
B. the velocity of the electron changes
c. electrostatic force due to the nucleus at the electron changes
D. none of these

12
1066The Gaussian surface for calculating the electric field due to a charge
distribution is
A. any closed surface around the charge distribution
B. any surface near the charge distribution
c. a spherical surface
D. a closed surface at a every point of which electric field has a normal component which is zero or a fixed value
12
1067Arrange electron(e), proton (p) and deuteron(d) in the increasing order of their specific charge:
A ( . e>p<d )
B. ( d<pe>d )
D. ( d>e>p )
12
1068What is the direction of the electric field directly to the east of an isolated
negative point charge?
A. North
B. South
( c . ) East
D. west
E. Up
12
1069State whether the given statement is
True or False :

Conductors when charged transfer all
charges to the entire surface of the
conductor.
A. True
B. False

12
1070The electric field within the nucleus is
generally observed to be linearly dependent on ( r . ) This implies.
A ( . a=0 )
B. ( a=frac{R}{2} )
( mathbf{c} cdot a=R )
D ( a=frac{2 R}{3} )
12
1071A point charge ( boldsymbol{q}=mathbf{1 0 0} mu boldsymbol{C} ) is located in
the ( x ) -y plane at the point with position vector ( vec{r}_{0}=2 hat{i}+3 hat{j}+hat{k} . ) What is the
electric field vector(in ( mathrm{kV} / mathrm{m} ) ) at the
point with position vector ( vec{r}=8 hat{i}- ) ( mathbf{5} hat{boldsymbol{j}}+hat{boldsymbol{k}} ? )
( mathbf{A} cdot 4 cdot 2 hat{i}-5.6 hat{j} )
в. ( 6 hat{i}-8 hat{j} )
c. ( 54 hat{i}-72 hat{j} )
D. ( 5.4 hat{i}-7.2 hat{j} )
12
1072Three charges ( +4 q, Q ) and ( q ) are placed in a straight line of length I at points at distances ( 0,1 / 2, ) and I respectively. What should be ( Q ) in order to make the
net force on q to be zero?
( A cdot-q )
B. -29
( c cdot-frac{q}{2} )
D. 49
12
1073The electric potential at a point ( boldsymbol{P} ) inside a uniformly charged conducting sphere of radius ( R ) and charge ( Q ) at a
distance ( r ) from the centre is :
A . 0
B . ( infty )
c. ( frac{Q}{4 pi epsilon_{0} r} )
D. ( frac{Q}{4 pi epsilon_{0} R} )
12
1074Two point charge -q and +q/2 are situated at the origin and the point ( (a, 0,0) ) respectively. The point along the X-axis where the electric field vanishes
is
A ( cdot x=frac{a}{sqrt{2}} )
В. ( x=sqrt{2} a )
c. ( x=frac{sqrt{2} a}{sqrt{2}-1} )
D. ( x=frac{sqrt{2} a}{sqrt{2}+1} )
12
1075A hollow chaeged mental sphere has radius ( r . ) if the potential difference between its surface and a point at a distance ( 3 r ) from the center is ‘v’ then
electric field intensity at a distance 3 r
is
A ( cdot frac{v}{2 r} )
B. ( frac{v}{3 r} )
c. ( frac{v}{6 r} )
D. ( frac{v}{4 r} )
12
1076If a body is positively charged, then it
has
A. Excess of electrons
B. Excess of protons
c. Deficiency of electrons
D. Deficiency of neutrons
12
1077Five balls, numbered 1 to ( 5, ) are suspended using separate threads. Pairs (1,2),(2,4),(4,1)
show electrostatic attraction, while pairs (2,3) and (4,5) show repulsion therefore ball 1 must be:
A. Positively charged
B. Negatively chargedd
c. Neutral
12
1078Write the expression for electric intensity at a point due to point charge and explain the terms.12
1079The self potential energy of hydrogen chloride whose dipole moment is ( 3.44 times ) ( 10^{-20} mathrm{Cm} ) and separation between
hydrogen and chlorine atoms is ( 1.01 times )
( 10^{-10} mathrm{m} ) is:
В. ( 3.2 times 10^{5} J )
c. ( 4.5 times 10^{7} J )
D. ( 1.65 times 10^{6} J )
12
1080A polished, silvery surface is a:
A. Good absorber and good reflector of heat
C. Poor absorber and good reflector of heat
D. Poor reflector and good radiator of heat
12
1081The electric field between the plates of
two oppositely charged plane sheets of
charge density’ ( sigma^{prime} ) is :
A ( cdot+frac{sigma}{2 epsilon_{0}} )
в. ( -frac{sigma}{2 epsilon_{0}} )
c. ( frac{sigma}{epsilon_{0}} )
D. zero
12
1082Ordinary tap water conducts electric
current due to :
A. the dissolved salts in it it
B. higher purity of the water
c. the bacteria present in it it
D. none of these
12
1083In the nucleus of helium, if ( F_{1} ) is the net
force between two protons, ( F_{2} ) is the net
force between two neutrons and ( F_{3} ) is the
net force between a proton and a neutron.
Then
A ( cdot F_{1}=F_{2}=F_{3} )
в. ( F_{1}>F_{2}>F_{3} )
c. ( F_{2}>F_{3}>F_{1} )
D. ( F_{2}=F_{3}>F_{1} )
12
1084Pictured above is a red point charge and
a blue point charge. The blue point charge is moved from loication 1 to location 2. The force
between the point charges is ( 5.00 mathrm{N} )
when blue charge is at location 1
How much force exist between the point charges when the blue charges is at
location 2?
A . 25.0
B. 30.0 N
c. ( 125 mathrm{N} )
D. ( 180 mathrm{N} )
E . ( 1.0 mathrm{N} )
12
1085For spherical symmetrical charge
distribution, variation of electric
potential with distance fro center is
given in diagram. Given that ( : V= ) ( frac{boldsymbol{q}}{mathbf{4} boldsymbol{pi} varepsilon_{0} boldsymbol{R}_{0}} ) for ( boldsymbol{r} leq boldsymbol{R}_{0} ) and ( boldsymbol{v}=frac{boldsymbol{q}}{boldsymbol{4} boldsymbol{pi} varepsilon_{0} boldsymbol{r}} ) for
( boldsymbol{r} geq boldsymbol{R}_{0} )
Then which option (s) are correct:
This question has multiple correct options
A. Total charge within ( 2 R_{0} ) is 9
B. Total electrostatic energy for ( r leq R_{0} ) is non-zer
c. ( A t r=R_{0} ) electric field is discontinuous
D. There will be no charge anywhere except at ( r<R_{0} )
12
1086A positive test charge is released from rest in a uniform electric field. Which of
the following best describes its initial
motion?
A. It will move with constant velocity along an equipotential line
B. It will move with constant acceleration along an equipotential line
c. It will move with constant acceleration along an electric field line
D. It will move with constant velocity along an electric field line
12
1087The safety fuse should have
A. high resistance and high melting point
B. high resistance and low melting point
C. low resistance and high melting point
D. low resistance and low melting point
12
1088An inclined plane making an angle ( 30^{circ} )
with the horizontal is placed in a uniform horizontal electric field of
( 100 V m^{-1} . ) A particle of mass ( 1 k g ) and
charge ( 0.01 C ) is allowed to slide down
from rest from the top of the inclined plane. If the coefficient of friction is 0.2
the particle reaches the bottom of the
inclined plane in 1 second. Then the length of the inclined plane is (Acceleration due to gravity ( =10 m s^{-2} ) )
A ( .1 .150 m )
в. ( 1.323 m )
c. ( 1.151 m )
D. ( 1.172 m )
12
1089A charge of +2 nC is separated from a charge of ( -2 mathrm{nC} ) by ( 1.5 mathrm{cm} ) forming an electric dipole. What torque acts on the
dipole moment vector makes an angle
of ( 30^{0} ) in the clockwise sense with the
field of magnitude ( 5000 mathrm{N} / mathrm{C} ? )
12
1090The charge on an electron was calculated by:
B. J.J Thompson
c. Millikan
D. Einstein
12
1091In a region of space, the electric field is given by ( overrightarrow{boldsymbol{E}}=mathbf{8} hat{mathbf{i}}+mathbf{4} hat{mathbf{j}}+mathbf{3} hat{boldsymbol{k}} . ) The electric
flux through a surface of area 100 units in the xy plane is :
A. 800 units
B. 300 units
c. 400 units
D. 1500 units
12
1092There are two non conducting spheres
having uniform volume charge
densities ( rho ) and ( -rho . ) Both spheres have
equal radius R. The spheres are now laid
down such that they overlap as shown in the figure. The electric field ( overrightarrow{boldsymbol{E}} ) in the
overlap region is :
A. non uniform
B. zero
c. ( frac{rho}{3 epsilon_{0}} vec{d} )
12
1093When a glass rod is rubbed with a piece
of silk cloth the rod
( A cdot ) and the cloth both acquire positive charge
B. becomes positively charged while the cloth has a negative charge
( mathrm{C} ). and the cloth both acquire negative charge
D. becomes negatively charged while the cloth has a positive charge
12
1094Four particles, each having charge ( boldsymbol{q} )
are placed at four verticals of a regular
pentagon. The distance of each corner
from the center is ( a ). The electric field at
the center ( O ) of the pentagon is:
A ( cdot frac{q}{4 pi epsilon_{0} a^{4}} ) along ( E O )
B. ( frac{q}{2 pi epsilon_{0} a^{2}} ) along ( E O )
c. ( frac{q}{pi epsilon_{0} a^{2}} ) along ( E O )
D. ( frac{q}{4 pi epsilon_{0} a^{2}} ) along ( E O )
12
1095Complete the following statements with an appropriate word /term be filled in
the blank space(s).
The force of attraction or repulsion
between two charges is given by
A. Gauss’s law
B. Kepler’s law
c. Coulomb’s law
D. Gravitational law
12
1096Four charges are arranged at the corners
of a square ( mathrm{ABCD} ) as shown in the figure. If a test charge is placed at the centre calculate the direction of net force on that
charge.
A. zero
B. along the diagonal AC
c. along the diagonal BD
D. perpendicular to side AB
12
1097A molecule with a dipole moment p is placed in electric field of strength E. Initially the dipole is aligned parallel to the field. If the dipole is to be rotated to be anti parallel to the field, the work required to be done by an external agency is
A . – 2pE
B . -pE
c. pE
D. 2pE
12
1098Two ball ( A ) and ( B ) of same mass ( (M) )
and charges ( Q,-Q ) are suspended by
two strings of same length from two
different suspension points ( S_{1} ) and ( S_{2} ) if
( S_{1} S_{2}=3 x ) and ( A B=x ) then show that
tension in the string is ( T=frac{Q^{2} L}{4 pi in_{0} x^{3}} ) ( tan theta=frac{Q^{2}}{4 pi in_{0} x^{2} M g} )
12
1099Four positive charges ( (2 sqrt{2}-1) Q ) are
arranged at the four corner of a square. Another charge q is placed at the centre of the square. Resulting force acting on each corner charge is zero if q is :
A ( cdot frac{-7 Q}{4} )
в. ( frac{-4 Q}{7} )
( c cdot-Q )
D. ( -(sqrt{2}+1) Q )
12
1100Find the maximum intensity ( mathrm{E}_{max } ) and
the corresponding distance ( r_{m} )
12
1101State one activity to prove that air is a bad conductor of electricity12
1102The figure shows schematic field lines
resulting from interaction between
A . two positive charges
B. two negative charges
c. a positive and a negative charge
D. None of these
12
1103Two metallic spheres ( A ) and ( B ) are made of same material and have got an identical surface finish. The mass of
sphere ( mathbf{A} ) is four times that of ( mathbf{B} . ) Both
the spheres are heated to the same
temperature and placed in a room having a lower temperature but thermally insulated from each other.
A. The ratio of heat loss of A to that of B is ( 2^{4 / 3} )
B. The ratio of heat loss of A to that of B is ( 2^{2 / 3} )
C. The ratio of the initial rate of cooling of A to that of B is ( 2^{2 / 3} )
D. The ratio of the initial rate of cooling of ( A ) to that of ( B ) is ( 2^{-1 / 3} )
12
1104In the given figure, electric lines of force
diagram is shown. Then:
A ( cdot E_{A}E_{B}>E_{C} )
( mathbf{c} cdot E_{C}>E_{B} )
( mathbf{D} cdot E_{A}=E_{B}=E_{C} )
12
1105Two identical copper spheres carrying chatges ( +Q ) and ( -9 Q ) separated by a certain distance has attractive force ( F )
If the spheres are allowed to touch eacxh other and moved to distance of
separation ‘x’. So that the force between
them becomes ( frac{4 F}{9} . ) Then ( x ) is equal to
( A cdot d )
B. 2d
( c cdot d / 2 )
D. 4d
12
1106Four charges are placed at the
circumference of dial clock as shown in
figure. If the clock has only hour hand,
then the resultant force on a positive
charge ( q_{0} ) placed at the centre, points in
the direction which show the time as:
( mathbf{A} cdot 1: 30 )
B. 7: 30
( c cdot 4: 30 )
D. 10: 30
12
1107When a comb rubbed with dry hair
attracts pieces of paper. This is
because the
A. comb polarizes the piece of paper
B. comb induces a net dipole moment opposite to the direction of field
c. electric field due to the comb is uniform
D. comb induces a net dipole moment perpendicular to the direction of field
E. paper acquires a net charge
12
1108During discharging of a charged glass rod via earthing, the connecting material can be
A. another glass rod
B. a conducting wire
( c . ) fur
D. an ebonite rod
12
1109A charge ( Q ) is uniformly distributed over the surface of two concentric
conducting spheres of radii ( R ) and ( r )
( (R>r) ) such that surface charge
densities are same for both spheres.
Then potential at the common center of
these spheres is
A ( cdot frac{k Q(R+r)}{R r} )
B. ( frac{k Q(R+r)}{left(R^{2}+r^{2}right)} )
c. ( frac{k Q}{sqrt{R^{2}+r^{2}}} )
D ( quad k Qleft(frac{1}{R}-frac{1}{r}right) )
12
1110Identify incorrect for electric charge ( boldsymbol{q} )
A. Quantised
B. Conserved
D. Non-transferable
12
1111Electric flux is a
A. scalar
B. vector
c. constant
D. independent
12
1112Intensity of an electric field (E) depends on distance ( r . ) In case of dipole, it is
related as:
( ^{mathrm{A}}=_{E} propto frac{1}{r} )
в. ( quad E propto frac{1}{r^{2}} )
c. ( quad E propto frac{1}{r^{3}} )
D. ( quad E propto frac{1}{r^{4}} )
12
1113The gravitational force is
A. always attractive
B. always repulsive
C. either attractive or repulsive
D. None of these
12
1114A metal sphere is kept on an insulating stand. A negatively charged rod is
brought near it, then the sphere is
earthed as shown. On removing the earthing, and taking the negatively
charged rod away, what will be the
nature of charge on the sphere? Give

Ground

12
1115A radio active nucleus (initial mass number A and atomic number Z emits 4
( alpha ) – particles and 3 positrons).The ratio
of numbers of neutrons to that of
protons in the final nucleus will be
A ( cdot frac{A-Z-4}{Z-8} )
B. ( frac{A-Z-3}{Z-2} )
c. ( frac{A-Z-2}{Z-3} )
D. ( frac{A-Z-5}{Z-11} )
12
1116Figure shows some of the electric field
lines corresponding to an electric field.
The figure suggests that:
A ( cdot E_{A}>E_{B}>E_{C} )
B . ( E_{A}=E_{B}=E_{O} )
( mathbf{c} cdot E_{A}=E_{C}>E_{B} )
D. ( E_{A}=E_{C}<E_{B} )
12
1117Three charges ( -q_{1},+q_{2} ) and ( -q_{3} ) are placed
as shown in the figure. The ( x ) -component
of the force on ( -q_{1} ) is proportional to:
A ( cdot frac{q_{2}}{b^{2}}-frac{q_{3}}{a^{2}} cos theta )
B ( cdot frac{q_{2}}{b^{2}}+frac{q_{3}}{a^{2}} sin theta )
C ( cdot frac{q_{2}}{b^{2}}+frac{q_{3}}{a^{2}} cos theta )
D. ( frac{q_{2}}{b^{2}}-frac{q_{3}}{a^{2}} sin theta )
12
1118A neutral rubber rod and a neutral piece
of fur have equal amounts of negative and positive charge. When the fur is rubbed against the rod, a transfer of electrons occurs. The transfer of
electrons and mass
transfer respectively takes place from
A. fur to rubber rod; rubber rod to fur
B. fur to rubber rod; fur to rubber rod
c. rubber rod to fur; rubber rod to fur
D. rubber rod to fur; fur to rubber rod
12
1119Assertion
At a point in space, the electric field points towards north. In the region,
surrounding this point the rate of
change of potential will be zero along
the east and west
Reason
Electric field due to a charge is in the
space around the charge
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason is correct
12
1120Sparking occurs when a load is switched off because the circuit has
high :
A . resistance
B. inductance
c. capacitance
D. impedance
12
1121Mass of negative ion is slightly greater than its neutral atom.
A. True
B. False
12
1122State Coulomb’s law.12
1123What is the work done in rotating the
dipole through ( 180^{circ} ? )
A ( cdot frac{partial q Q x}{pi varepsilon_{0}left(R^{2}+x^{2}right)^{3 / 2}} )
В. ( frac{partial q Q x}{2 pi varepsilon_{0}left(R^{2}+x^{2}right)^{3 / 2}} )
c. ( frac{2 partial q Q x}{pi varepsilon_{0}left(R^{2}+x^{2}right)^{3 / 2}} )
D. ( frac{partial q Q x}{3 pi varepsilon_{0}left(R^{2}+x^{2}right)^{3 / 2}} )
12
1124Two small objects each with a net charge of ( +Q ) exert a force of magnitude Fon each other. We replace one of the objects with another whose net charge is ( +4 Q . ) We move the ( +Q ) and ( +4 Q ) charges to be 3 times as far apart as they were. What is the magnitude of the force on the ( +4 Q ) charge?
( A cdot F )
B. 4F
( c cdot 4 F / 3 )
D. 4F/9
E. F/3
12
1125The electric field in a region of space is
given by ( boldsymbol{E}=mathbf{5} boldsymbol{i}+mathbf{2} boldsymbol{j} boldsymbol{N} / boldsymbol{C} . ) Determine
the electric flux due to this field
through an area ( 2 m^{2} ) lying in the ( Y Z ) plane:
A . 10
B . 20
c. ( 10 sqrt{2} )
(
D. ( 2 sqrt{29} )
12
1126A charges of ( 8.7 times 10^{-18} C )
A. Does exist
B. Does not exist
c. Exists for a short time
D. Exists only if placed in higher orbits
12
1127Electric charge is measured in
A . coulombs
B. amperes
c. volts
D. watts
12
1128A large sheet carries uniform surface charge density ( sigma . ) A rod length ( 2 l ) has a linear charge density ( lambda ) on one half and ( -lambda ) on the second half. The rod is hinged at the midpoint 0 and makes and angle ( theta ) with the normal to the sheet. The
torque experienced by the rod is:
( A cdot O )
B. ( frac{sigma lambda l^{2}}{2 varepsilon_{0}} sin theta )
( ^{text {c. }} frac{sigma lambda l^{2}}{varepsilon_{0}} sin theta )
D. ( frac{sigma lambda l}{2 varepsilon_{0}} )
12
1129Consider the motion of a positive point charge in a region where there are simultaneous uniform electric and
magnetic fields ( mathrm{E}=mathrm{EO} mathrm{j} ) and ( mathrm{B}=mathrm{BO} mathrm{j}, mathrm{At} )
time ( t=0, ) this charge has velocity ( v ) in the ( x ) -y plane, making an angle 0 with the ( x ) -axis. Which of the following option(s) is(are) correct for time ( t>0 ? )
12
1130A charged particle q of mass m is in
equilibrium at a height h from a horizontal infinite line charge with
uniform linear charge density ( lambda ). The
charge lies in the vertical plane containing the line charge. If the particle is displaced slightly (vertically), prove that the motion of the charged particle will be simple harmonic. Also find its time period
12
1131A straight segment ( O C ) (of length ( L ) ) of
a circuit carrying a current ( I ) is placed along the ( x ) -axis. Two infinitely long straight wires ( A ) and ( B ), each extending
from ( z=-infty ) to ( +infty, ) are fixed at ( y= )
( -a ) and ( y=+a ) respectively, as shown
in the figure. If the wires ( A ) and ( B ) each
carry a current ( I ) into the plane of the
paper, obtain the expression for the force acting ont he segment ( O C . ) What
will be the force on ( O C ) if the current in
the wire ( B ) is reversed?
12
1132A charge ( q_{0} ) is brought from infinity to the centre of dipole. Find work done?
в. ( 0 . )
( c cdot 3 J )
D. ( 4 J )
12
1133A and B are two points on the axis and
the perpendicular bisector, respectively
of an electric dipole. A and B are far
away from the dipole and at equal
distances from it. The fields at ( A ) and ( B )
( operatorname{are} vec{E}_{A} ) and ( vec{E}_{B} . ) Then:
( mathbf{A} cdot vec{E}_{A}=vec{E}_{B} )
B ( cdot vec{E}_{A}=2 vec{E}_{B} )
( mathbf{c} cdot vec{E}_{A}=-2 vec{E}_{B} )
D ( cdotleft|vec{E}_{B}right|=frac{1}{2}left|vec{E}_{A}right| ), and ( left|vec{E}_{A}right| ) is perpendicular to ( vec{E}_{B} )
12
1134Which of the following is best insulator?
A. Carbon
B. Paper
c. Graphite
D. Ebonite
12
1135How many electronic charges from 1 coulomb?
A. ( 9.1 times 10^{-31} )
B . ( 1.6 times 10^{18} )
c. ( 62.5 times 10^{17} )
D. ( 1.76 times 10^{11} )
12
1136Identify the correct statement:
( A ). ( A ) and ( B ) will have the same mass afterwards.
B. A will have more mass than B afterwards.
C. A will have lesser mass than B afterwards.
D. None of these
12
1137A solid sphere of radius ( R ) has a charge
( +2 Q . ) A hollow spherical shell of radius
( 3 R ) placed concentric with the first
sphere has net charge – ( Q ). Calculate
the potential difference between the
spheres:
( ^{A} cdot frac{Q}{3 pi varepsilon_{0} R} )
в. ( frac{2 Q}{3 pi varepsilon_{Omega} R} )
c. ( frac{3 Q}{pi varepsilon_{0} R} )
( D )
12
1138Two fixed point charges ( +4 e ) and ( +e ) are
separated by a distance a. Where should the third point charge be placed
from ( +4 e ) charge for it to be in equilibrium?
A ( cdot frac{2}{3} a )
в. ( frac{4}{3} a )
( c cdot frac{1}{3} a )
D. None of these
12
1139Explain why a charged balloon is
repelled by another charged balloon
whereas an uncharged balloon is attracted by another charged balloon?
12
1140An electric dipole kept in a uniform electric field experiences:
A. Force and a torque
B. A force, but no torque
c. A torque but no force
D. Neither a force nor a torque
12
1141Four identical charges of charge ( q ) are
placed at the corners of a square of
sides r as shown above. Find the
magnitude of the net force acting on a
charge of magnitude ( 2 q ) placed in the
center of the square.
( mathbf{A} cdot mathbf{0} )
( mathbf{B} cdot frac{2 k q^{2}}{r^{2}} )
( mathbf{c} cdot frac{4 k q^{2}}{r^{2}} )
D. ( frac{16 k q^{2}}{r^{2}} )
E ( cdot frac{text { g } 2 k q^{2}}{r^{2}} )
12
1142A charge ( Q ) is distributed uniformly in a sphere (solid). Then the electric field at any point r where ( r<R ) (R is radius of the sphere) varies as
A ( cdot r^{1 / 2} )
B ( cdot r^{-1} )
( c )
D. ( r^{-2} )
12
1143Assertion
A charge ( q ) is placed inside the square of side b. The flux associated with the
square is independent of side length.
Reason

Gauss’s law is independent of size of
the Gaussian surface.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect

12
1144The equi-potential surface for an
electric dipole is:
A. the dipole axis
B. the perpendicular bisector of the dipole axis
C. a line parallel to the dipole axis
D. a line passing through one of the charges
12
1145Four electric charges are arranged as shown in the figure at the four corners of a square of side a. The potential energy of the system is:
A. Zero
B. Negative
c. Positive
D. Greater than ( frac{1}{4 pi varepsilon} frac{2 q^{2}}{a} )
12
1146A charged particle of mass ( 5 times 10^{-6} k g )
is held stationary in space by placing it
in an electric field of strength ( 10^{6} N C^{-1} ) directed vertically downwards. The charge on the particle is ( left(boldsymbol{g}=mathbf{1 0 m} boldsymbol{s}^{-2}right) )
A. ( -20 times 10^{-5} mu C )
B. ( -5 times 10^{-5} mu C )
c. ( 5 times 10^{-5} mu C )
D. ( 20 times 10^{-5} mu C )
12
1147For ( a=0, ) the value of ( d( ) maximum
value of ( rho ) as shown in the figure) is
( ^{A} cdot frac{3 Z e}{4 pi R^{3}} )
в. ( frac{3 Z}{pi R^{3}} )
c. ( frac{4 Z e}{3 pi R^{3}} )
D. ( frac{Z e}{3 pi R^{3}} )
12
1148Two concentric spheres of radii R and 2R are charged. The inner sphere has a
charge of ( 1 mu mathrm{C} ) and the outer sphere has a charge of ( 2 mu mathrm{C} ) of the same sign: The potential is ( 9000 mathrm{V} ) at a distance ( 3 mathrm{R} )
from the common centre. The value of ( mathrm{R} )
is :
( A cdot 1 m )
B. 2 ( m )
( c cdot 3 m )
D. ( 4 mathrm{m} )
12
1149Two conducting concentric, hollow spheres ( A ) and ( B ) have radii a and ( b ) respectively, with A inside B.Their common potentials is ( V ). A is now given some charge such that its potential becomes zero. The potential of B will
now be :
A. 0
B. ( V(1-a / b) )
c. ( v ) a/b
D. v b/a
12
1150State True or False :
Human body is a good conductor of electricity.
A. True
B. False
12
1151Assertion
Gauss theorem can be applied only for a
closed surface.
Reason
Electric flux can be obtained passing
from an open surface also.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
1152Three concentric conducting spherical
shells of radii ( boldsymbol{R}, 2 boldsymbol{R} ) and ( boldsymbol{3} boldsymbol{R} ) carry
charges ( Q,-2 Q ) and ( 3 Q, ) respectively
Find the electric potential at ( r=R ) and
( boldsymbol{r}=boldsymbol{3} boldsymbol{R}, ) where ( boldsymbol{r} ) is the radial distance
from the centre
( ^{mathrm{A}} cdot frac{Q}{6 pi varepsilon_{0} R}, frac{Q}{4 pi varepsilon_{0} R} )
в. ( frac{Q}{4 pi varepsilon_{0} R}, frac{Q}{6 pi varepsilon_{0} R} )
c. ( frac{Q}{2 pi varepsilon_{0} R}, frac{Q}{3 pi varepsilon_{0} R} )
D. ( frac{Q}{3 pi varepsilon_{0} R}, frac{Q}{2 pi varepsilon_{0} R} )
12
1153( y= )
( x )
0
12
1154Observe the circit in the figure. Which of
the following materials can be used to complete the open fruit and light the
bloub
[Paper, rubber bandm, steel spon silk, plastic, nail, blade]
12
1155The electric field at ( r=R ) is:
A. independent of a
B. directly proportional to a
C. directly proportional to ( a^{2} )
D. inversely proportional to
12
1156Between two plates charged to ( 10 q ) there is an electric field ( E, ) what acceleration
will a positively charged particle, with a charge of ( q ) and a mass of ( m )
experience in this region, due only the electric field?
( ^{text {A } cdot frac{21 q E}{m}} )
в. ( frac{11 q E}{m} )
( ^{mathbf{c}} cdot frac{10 q E}{m} )
D. ( frac{q E}{m} )
12
1157Find the electric flux through each of
the six cube faces ( S_{1}, S_{2}, S_{3}, S_{4}, S_{5} ) and
( boldsymbol{S}_{6} )
12
1158Six charges are kept at the vertices of a regular hexagon as shown in the figure. f magnitude of force applied by ( +Q ) on ( +q ) charge is ( F ), then net electric force
on the ( +Q ) is ( n F ). Find the value of ( n )
12
1159Rub a glass rod with a piece of silk. What happens?
A. the glass has a slightly positive charge and the silk is also slightly positive
B. the glass has a slightly positive charge and the silk is slightly negative
C. the glass has a slightly negative charge and the silk is also slightly negative
D. the glass has a slightly negative charge and the silk is slightly positive
12
1160A conductive base is provided to the
gold-leaf electroscope so that
A. the leaves discharge before tearing if an excess charge is applied.
B. the leaves discharge before tearing if negative charge is applied.
c. the leaves discharge before tearing if positive charge is applied.
D. All of the above
12
1161State whether true or false:
Unlike charges attract each other
A. True
B. False
12
1162Match the terms in column I with those
of column II
( begin{array}{ll}text { Column – I } & text { Column – II } \ text { i. Electric fuse } & text { A. Chemical effect } \ text { ii. Relay } & text { B. Electric discharge } \ text { iii. CFL } & text { C. Magnetic effect } \ text { iv. Button cell } & text { D. Heating effect }end{array} )
iii-A, iv-D
( A cdot ) i-C, ii-B,
B. i-B, ii-A, iii-C, iv-D
c. i-D, ii-C, iii-B, iv-A
D. i-D, ii-B, iii-C, iv-D
12
1163Electric field at point (30,30,0) due to a
point charge of ( 8 times 10^{-3} mu C ) placed at
origin will be (coordinates are in ( mathrm{cm} ) )
A. ( 8000 N / C )
в. ( 4000(hat{i}+hat{j}) N / C )
c. ( 200 sqrt{2}(hat{i}+hat{j}) N / C )
D. ( 400 sqrt{2}(hat{i}+hat{j}) N / C )
12
1164A charge ( Q ) is enclosed by a Gaussian spherical surface of radius R. If the
radius is doubled, then the outward
electric flux will :
A. be doubled
B. increase four times
c. be reduced to half
D. remain the same
12
1165Two thin infinite parallel sheets have uniform surface densities of charge ( +boldsymbol{sigma} )
and ( -sigma . ) Electric field in the space
between the two sheets is:
A ( cdot sigma / epsilon_{0} )
в. ( sigma / 2 epsilon_{0} )
( mathbf{c} cdot 2 sigma / epsilon_{0} )
D. zero
12
1166A comb run through ones hair attracts
small bits of paper. What happens, if
the hair are wet or if it is a rainy day?
A. The comb does not get charged and it will not attract small bits of paper
B. The comb does not get charged but it will attract small bits of paper.
C. The comb does gets charged and it will attract small bits of paper.
D. The comb does gets charged but it will not attract small bits of paper.
12
1167A cube of side ( 20 mathrm{cm} ) is kept in a region
as shown in the figure. An electric field
( vec{E} ) exists in the region such that the
potential at a point is given by ( boldsymbol{V}= )
( 10 x+5, ) where ( V ) is in volt and ( x ) is in ( m )
Find the electric flux through the cube
12
1168What will be the electric flux through
the sphere ( S_{1} ) if a medium of dielectric
constant ( epsilon_{r} ) is introduced in the
space inside ( S_{1} ) in place of air
A. ( frac{20}{epsilon epsilon_{n}} )
в. ( frac{40}{epsilon_{0} epsilon_{r}} )
c. ( frac{20 epsilon_{c}}{epsilon_{0}} )
D. ( frac{406}{6} )
12
1169For an ideal conductor thermal
resistance is :
A. unity
B. infinity
c. zero
D. 1000
12
1170A charge particle of mass ‘m’ & charge q is released from rest from a given position ( Q ) inside a fixed vertical
semicircular trough. For the presence and the absence of magnetic field
normal reaction acting on the change at
Pare ( N_{1} ) and ( N_{2} ) respectively. Neglecting friction and assuming
gravity presence. The value of ( N_{1}-N_{2} )
is:
A ( .2 B q sqrt{2 g R} )
в. ( frac{B q sqrt{2 g R}}{2} )
с. ( B q sqrt{2 g R} )
D. ( frac{B q sqrt{2 g R}}{4} )
12
1171( operatorname{Let} rho(r)=frac{Q r}{4 pi R^{4}} ) be the charge density
distribution of a solid sphere of radius ( R ) and total charge ( Q . ) Find the magnitude of electric field at a point ( boldsymbol{P} )
inside the sphere at a distance ( r_{1} ) from
the centre of the sphere.
A ( cdot frac{Q}{4 pi^{2} epsilon_{6} r_{1}^{2}} )
в. ( frac{Q r_{1}^{2}}{4 pi^{2} epsilon_{epsilon} R^{4}} )
c. ( frac{Q r_{1}^{2}}{16 pi epsilon_{1} R^{4}} )
D. 0
12
1172The total solid angle subtended by the sphere is
( mathbf{A} cdot 0.25 pi )
в. ( 0.5 pi )
c. ( 4 pi )
D . ( 2 pi )
E . ( 1 pi )
12
1173Using Gauss’s law derive an expression for the electric field intensity due to a uniform charged thin spherical shell at a point.
(i) Outside the shell
(ii) Inside the shell
12
1174Two equal positive charges ( Q ) are fixed at points ( (a, 0) ) and ( (-a, 0) ) on the ( x ) axis. An opposite charge ( -q ) at rest is released from point ( (0, a) ) on the ( y ) -axis.
The charge ( -boldsymbol{q} ) will
A. move to infinity
B. Move to origin and rest there
c. Undergo SHM about the origin
D. Execute oscillatory periodic motion but not SHM
12
1175Two isolated metallic solid spheres of
radii ( boldsymbol{R} ) and ( 2 boldsymbol{R} ) are charged such that
both of these have same charge density
( rho . ) The spheres are located far away from each other, and connected by a thin conducting wire. Then the new charge
density on the bigger sphere is:
12
1176Two charged objects are brought close
to each other. Choose the most
appropriate statement from the following options:
A. they may attract
B. they may repel
c. they may attract or repel depending on the type of charges they carry
D. there will be no effect
12
1177State Gauss theorem and uses it to
derive the Coulomb’s inverse square
law.
12
1178Can a body have a charge of ( 4.8 times 10^{-20} )
coulomb?
A. Yes
B. No
c. мау be
D. only semiconductors can have
12
1179A charge can exist without mass.
A. True
B. False
12
1180Which of the following represents the electric field lines due to a combination
of two negative charges?
( A )
B.
( c )
( D )
12
1181Let there be a spherically symmetric
charge distribution with charge density ( operatorname{varying} operatorname{as} rho(r)=rho_{0}left(frac{5}{4}-frac{r}{R}right) ) upto ( r= )
( R, ) and ( rho(r)=0 ) for ( r>R, ) where ( r ) is
the distance from the origin. Find the
electric field at a distance ( r(r<R) )
from the origin.
A ( cdot frac{3 rho_{0} r}{4 epsilon_{0}}left(frac{5}{3}-frac{r}{R}right) )
В ( cdot frac{4 rho_{0} r}{3 epsilon_{0}}left(frac{5}{3}-frac{r}{R}right) )
C ( cdot frac{rho_{0} r}{4 epsilon_{0}}left(frac{5}{3}-frac{r}{R}right) )
D. ( frac{3 rho_{0} r}{4 epsilon_{0}}left(frac{5}{4}-frac{r}{R}right) )
12
1182An application of electrostatic
induction is

This question has multiple correct options
A. electric generator
B. Van de Graff generator
c. Wimhurst machine
D. transformer

12
1183Protons and neutrons inside the
nucleus are called
12
1184If the electric field to the right of the two
sheets is ( K sigma / varepsilon_{0} . ) Find ( mathrm{K} ? )
12
1185Who named positive and negative charges?
B. Gauss
c. Benjamin Franklin
D. Curie
12
1186A charge ( q ) is located at the centre of a
cube.The electric flux through any face is –
( mathbf{A} cdot frac{2 pi q}{6(4 pi varepsilon)} )
В. ( frac{4 pi q}{6(4 pi varepsilon)} )
( mathbf{c} cdot frac{pi q}{6(4 pi varepsilon)} )
D. ( frac{q}{6(4 pi varepsilon 0)} )
12
1187Name the physical quantity of which the unit is coulomb:
A. capacitance
B. charge
c. current
D. inductance
12
1188A circular plane sheet of radius ( 10 mathrm{cm} ) is
placed in a uniform electric field of ( mathbf{5} times mathbf{1 0}^{mathbf{5}} mathbf{N} quad mathbf{C}^{-1}, ) making an angle of ( mathbf{6 0}^{mathbf{0}} )
with field. The electric flux through the sheet is
( begin{array}{lll}text { A } cdot 1.36 times 10^{2} N & text { m }^{2} & C^{-1}end{array} )
B . ( 1.36 times 10^{4} N quad m^{2} quad C^{-1} )
( begin{array}{lll}text { С } cdot 0.515 times 10^{2} N & text { m }^{2} & C^{-1}end{array} )
( begin{array}{lll}text { D. } 0.515 times 10^{4} N & text { m }^{2} & C^{-1}end{array} )
12
1189A charged particle of mass ( 5 times 10^{-6} mathrm{kg} ) is
held stationary in space by placing it in an electric field of strength ( 10^{6} N / C )
directed vertically downwards. The charge on the particle is: ( left(g=10 m / s^{2}right) )
A. ( -20 times 10^{-5} mu C )
B. ( -5 times 10^{-5} mu C )
c. ( 5 times 10^{-5} mu C )
D. ( 20 times 10^{-5} mu C )
12
1190A metal sphere A of radius ( r_{1} ) charged
to a potential ( phi_{1} ) is enveloped by a thin
walled conducting spherical shell B of
radius ( r_{2} ). Then potential ( phi_{2} ) of the sphere ( A ) after it is connected to the
shell B by a thin conducting wire will be
A ( cdot phi_{1} frac{r_{1}}{r_{2}} )
В ( cdot phi_{1}left(frac{r_{2}}{r_{1}}right) )
c. ( phi_{1}left(1-frac{r_{2}}{r_{1}}right) )
( mathbf{D} cdot mathbf{q} phi_{1}left(frac{r_{1} r_{2}}{r_{1} r_{2}}right) )
12
1191A small ball of mass ( m ) and charge ( +q )
tied with a string of length ( l ) is rotating in a vertical circle under gravity and a
uniform horizontal electric field ( boldsymbol{E} ) as
shown. The tension in the string will be
minimum for:
A ( cdot quad theta=tan ^{-1}left(frac{q E}{m g}right) )
B . ( theta=pi )
( ^{mathbf{c}} cdot_{theta}=pi-tan ^{-1}left(frac{q E}{m g}right) )
D.
12
1192Above an infinitely large plane carrying
charge density ( sigma, ) the electric field points up and is equal to ( frac{sigma}{2 epsilon_{0}} . ) What is the magnitude and direction of the
electric field below the plane?
( A cdot sigma / 2 epsilon_{0}, ) down
В ( cdot sigma / 2 epsilon_{0}, ) up
( mathrm{c} cdot sigma / epsilon_{0}, ) down
D. ( sigma / epsilon_{0}, ) up
12
1193Which of the following may be discontinuous across a charged
conducting surface?
A. Electric potential
B. Electric intensity
c. Both electric intensity and potential
D. None of these
12
1194In the diagram shown, a positively charged rod is brought near the knob of an uncharged electroscope. The leaves will :
A. diverge and will be negatively chargedd
B. diverge and will be positively charged
C. converge and will be negatively chargedd
D. converge and will be positive chargedd
E. converge and will remain neutral
12
1195Which is the elementary quantum of energy?
A. Photon
B. Electron
c. Proton
D. Neutron
12
1196The electric field in a region is radially
outward with magnitude ( boldsymbol{E}=boldsymbol{alpha} boldsymbol{r} )
Calculate the charge contained in a sphere of radius ( R ) centered at the
origin. Calculate the value of the charge
if ( alpha=100 V m^{-2} ) and ( R=0.30 mathrm{m} )
A ( cdot 3 times 10^{-7} C )
В. ( 12 times 10^{-10} mathrm{C} )
c. ( 3 times 10^{-10} C )
D. ( 7 times 10^{-10} C )
12
1197Figure shows two large cylindrical
shells having uniform linear charge
densities ( +a lambda ) and ( -lambda . ) Radius of inner
cylinder as ‘a’ and that o outer cylinder
is ‘b’. A charged particle of mass m,
charge q revolves in a circle of radius
r.Then its speed ‘v’ is : (Neglect gravity and assume the radii of both the
cylinders to be very small in
comparision to their length)
A ( cdot sqrt{frac{lambda q}{2 pi epsilon_{0} m}} )
B. ( sqrt{frac{2 lambda q}{pi epsilon_{0} m}} )
c. ( sqrt{frac{lambda q}{pi epsilon_{0} m}} )
D. ( sqrt{frac{lambda q}{4 pi epsilon_{0} m}} )
12
1198Assertion
Insulators do not allow flow of current
through them.
Reason
Insulators have no free charge carriers.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is
not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect
12
1199What is the mangitude of a point
charge chosen so that electric field 50 ( mathrm{cm} ) away has magnitude ( 2.0 mathrm{N} / mathrm{C} ) ?
12
1200An infinite line charge is at the axis of a cylinder of length ( 1 mathrm{m} ) and radius ( 7 mathrm{cm} )
If electric field at any point on the
curved surface of cylinder is ( 250 N C^{-1} ) then net electric flux through the cylinder is:
12
1201Three point charges ( q ) are placed at three vertices of an equilateral triangle of side a. The magnitude of electric force on any charge due to the other two is equal to ( frac{sqrt{x}}{4 pi varepsilon_{0}}left(frac{q}{a}right)^{2} ) where ( x ) is:12
1202If the surface normal vector ( hat{n} ) makes an
angle ( theta ) with the electric field ( vec{E} ), then
the electric flux through a surface of
( operatorname{area} d S ) is given by
A. ( phi=E d S sin theta )
( mathbf{B} cdot phi=E d S cos theta )
c. ( phi=d S cos theta )
D. ( phi=E cos theta )
12
1203The Sl unit of charge is…..
A. ohm
B. volt
D. coulomb
12
1204Assertion
On going away from a point charge or a small electric dipole, electric field decreases at the same rate in both the
cases.
Reason
Electric field is inversely proportional to
square of distance from the charge or on electric dipole.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect.
D. Both Assertion and Reason are incorrect.
12
1205The tangent drawn on electric field lines
at a point gives the direction of lines of
force at that point.
A. True
B. False
12
1206A positive charge ( +mathrm{Q} ) is located at ( 5 mathrm{cm} )
on the positive y-axis. A negative charge
-Q is located at ( 5 mathrm{cm} ) on the positive ( x ) –
axis. A positive test charge is at the origin where it feels a force “F” from the
positive charge above it. What is the net
force from both charges?
( mathbf{A} cdot 2 F )
B ( . F^{2} )
( c cdot frac{F}{2} )
D. ( sqrt{2} F )
12
1207Some materials have electrons that are
tightly bound to the nucleus and are not free to travel within the substance.
These materials are called
A. conductors
B. insulators
c. semiconductors
D. none of these
12
1208The electric field at point Pjust outside the outer surface of a hollow spherical conductor of inner radius ( 10 mathrm{cm} ) and
outer radius ( 20 mathrm{cm} ) has magnitude 450 ( mathrm{N} / mathrm{C} ) and is directed outward. When an
unknown point charge ( Q ) is placed at the center of the sphere, the electric field at point ( P ) is still pointing outward but is now ( 180 mathrm{N} / mathrm{C} ). What is the value of
charge Q?
A . 4.5 nc
в. 1.5 nc
( c .-1.5 mathrm{nc} )
D. -1.2 nc
12
1209Two charges of magnitudes ( -2 Q ) and
( +Q ) are located at points ( (a, 0) ) and
( (4 a, 0) ) respectively. What is the electric
flux due to these charges through a
sphere of radius ( ^{prime} 3 a^{prime} ) with its centre at
the origin?
12
1210Using general logic for electric field, the flux of ( vec{g} ) through any closed surface is given by :
A ( cdot oint vec{g} cdot d vec{s}=4 pi G m_{text {endosed }} )
в. ( oint vec{g} cdot d vec{s}=-4 pi G m_{text {endosed }} )
c. ( oint vec{g} cdot d vec{s}=G m_{text {enclosed}} )
D ( cdot oint vec{g} cdot d vec{s}=-G m_{text {endose}} )
12
1211A ball with charge -50e is placed at the
centre of a hollow spherical shell has a
net charge of -50e. What is the charge on the shell’s outer surface?
A . – -50e
B. zero
( c cdot-100 e )
D. ( +100 e )
12
1212An electron of mass ( m_{e}, ) initially at rest,
move through a certain distance in a
uniform electric field in time ( t_{1} . A )
proton of mass ( m_{p}, ) also, initially at rest
takes time ( t_{2} ) to move through an equal distance in this uniform electric field.
Neglecting the effect of gravity, the ratio ( t_{2} / t_{1} ) is nearly equal to
A. 1
в. ( _{left(m_{p} / m_{e}right)^{1 / 2}} )
( ^{mathbf{c}} cdotleft(m_{e} / m_{p}right)^{1 / 2} )
D. 1836
12
1213If the distance between two unlike poles
is doubled then the force of attraction
between them becomes ( _{–}-_{-}- ) times
its original value
A . 0.25
B. 0.5
c. 0.125
D. 2
12
1214A charge 10 esu is placed at a distance of ( 2 mathrm{cm} ) from a charge 40 esu and ( 4 mathrm{cm} )
from another charge of 20 esu. The potential energy 10 esu in ergs is
A. 87.5
в. 112.5
( c cdot 150 )
D. 250
12
1215Two free charges ( +q ) and ( +4 q ) are
placed at a distance ( ^{prime} r^{prime} ) between them.
A third charge is placed in between them and find the third charge when the system is in equilibrium.
A ( cdot frac{4 q}{3} )
в. ( frac{4 q}{9} )
c. ( frac{2 q}{9} )
D. ( frac{q}{9} )
12
1216The cube as shown in Fig. has sides of
length ( boldsymbol{L}=mathbf{1 0 . 0} mathrm{cm} . ) The electric field is
uniform, has a magnitude ( boldsymbol{E}=mathbf{4 . 0 0} times )
( 10^{3} N C^{-1}, ) and is parallel to the ( x y- )
plane at an angle of ( 37^{circ} ) measured from
the ( +x-a x i s ) towards the ( +y-a x i s )
The surfaces that have zero flux are
( A cdot S_{1} ) and ( S_{3} )
B. ( S_{5} ) and ( S_{6} )
( c cdot S_{2} ) and ( S_{4} )
D. ( S_{1} ) and ( S_{1} )
12
1217Using Gauss’s theorem determine the electric field due to a uniformly charged sphere shell at a point which is12
1218An electron of mass ( M_{e}, ) initially at rest moves through a certain distance in a uniform electric field in time ( t_{1} . A )
proton of mass ( M_{p}, ) also initially at rest,
takes time ( t_{2}, ) to move through an equal distance in this uniform electric field.
Neglecting the effect of gravity, the ratio ( t_{2} / t_{1} ) is nearly equal to?
A . 1
в. ( sqrt{frac{M_{p}}{M_{e}}} )
c. ( sqrt{frac{M_{e}}{M_{p}}} )
D. 1836
12
1219In a region of space the electronic field is given by ( vec{E}=(8 hat{i}+4 hat{j}) N / C . ) The electric
flux through a surface of area ( 10 mathrm{m}^{2} ) in the
x-y plane is
A. 80 units
B. 40 units
c. 120 units
D. zero
12
1220Two pith balls carrying equal charges are suspended from a common point by strings of equal length, the equilibrium separation between them is r. Now the
strings are rigidly clamped at half the height. The equilibrium separation between the balls now become:
( A )
B. ( left(frac{r}{3 sqrt{2}}right) )
c. ( left(frac{2 r}{sqrt{3}}right) )
D. ( frac{2 r}{3} )
12
1221Assume that a neutron breaks into a
proton and an electron. The energy released during this process is : (mass of neutron ( =1.6725 times 10^{-27} k g, ) mass
of proton ( =1.6725 times 10^{-27} k g, ) mass of
electron ( left.=9 times 10^{-31} k gright) )
( mathbf{A} .5 .4 mathrm{MeV} )
в. ( 0.73 mathrm{MeV} )
c. ( 7.10 M e V )
D. ( 6.30 mathrm{MeV} )
12
1222An electric dipole will experience a net force when it is placed in :
A. Uniform electric field
B. A non-uniform electric field
c. Both the above cases
D. None of these
12
1223In electrical field, equipotential
surfaces must:
A. be plane surfaces
B. be tangential to the direction of field
C. be spaced such that surfaces having equal difference in potential are separated by equal distance
D. have decreasing potential in the direction of field
12
1224A point charge of ( +6 mu C ) is placed at a distance ( 20 mathrm{cm} ) directly above the centre of a square of side ( 40 mathrm{cm} . ) The magnitude of the flux through the
square is
( A cdot epsilon_{0} )
в. ( frac{1}{epsilon_{0}} )
c. ( epsilon_{0} times 10^{-6} )
D. ( frac{1}{epsilon_{0}} times 10^{-6} )
12
1225An electric dipole has the magnitude of its charge as ( q ) and its dipole moment is
( boldsymbol{p} . ) It is placed in uniform electric field ( boldsymbol{E} ) If its dipole moment is along the direction of the field, the force on it and
its potential energy are respectively
A. ( q . E ) and max
в. 2q.E and min
c. ( q . E ) and min
D. zero and min
12
1226An electric dipole of dipole moment ( 20 times 10^{-6} C ) is enclosed by closed
surface. What is the net electric flux
coming out of this surface?
12
1227At what separation should two equal charges, ( 1.0 C ) each, be placed so that
the force between them equals the
weight of a ( 50 k g ) person?
12
1228The electric field just outside the surface of conductor of area ( boldsymbol{A} ) and
surface charge density ( sigma ) is given by
A ( cdot frac{sigma}{3 epsilon_{0}} )
в. ( frac{sigma}{2 epsilon_{0}} )
c. ( frac{sigma}{epsilon_{0}} )
D. ( frac{2 sigma}{epsilon_{0}} )
12
1229Three charged particles are in equilibrium under their electrostatic forces only. Then
A. The particles must be collinear
B. All the charges cannot have the same magnitude
c. All the charges cannot have the same sign
D. The equilibrium is unstable
E. All option is correct
12
1230Charging by friction is accompanied by loss or gain of electrons. State which
body loses electrons when an ebonite rod is rubbed with fur.
A . ebonite
B. fur
c. hand
D. Both fur and ebonite
12
1231The charge on an electron is:
A . ( 1 mathrm{c} )
B ( cdot+1.6 times 10^{-19} mathrm{C} )
( mathrm{c} ldots 1.6 times 10^{-19} mathrm{C} )
D. 6.25 ( times 10^{18} mathrm{C} )
12
1232Why do electric lines of force never
intersect each other?
12
1233In a region of uniform electric field of
intensity ( boldsymbol{E}, ) an electron of mass ( boldsymbol{m}_{e} ) is relased from rest. The distance travelled
by the electron in a time ( t ) is:
( ^{mathbf{A}} cdot frac{2 m_{e} t^{2}}{e} )
B. ( frac{e E t^{2}}{2 m_{e}} )
( ^{mathbf{c}} cdot frac{m_{e} g t^{2}}{e E} )
D. ( frac{2 E t^{2}}{e m_{c}} )
12
1234Does the charge given to a metallic sphere depends on whether it is hollow or solid? Given reason for your answer.12
1235The electric field in a region is radially outward with magnitude ( mathrm{E}=2 mathrm{r} . ) The charge contained in a sphere of radius a
( =2 mathrm{m} ) centred at the origin is ( 4 x pi epsilon_{0} . ) Find
the value of ( x )
12
1237Two identical metallic spheres ( A ) and ( B ) of exactly equal masses are taken. Sphere ( A ) is given positive charge ( Q ) columb and B is given an equal negative charge. So initially before the
charge is given. What will be the masses after the charging?
12
1238If a point lies at a distance ( ^{prime} x^{prime} ) from the
mid point of the dipole along its axis, the electric potential at this point is proportional to :
A ( cdot frac{1}{x^{2}} )
B. ( frac{1}{x^{3}} )
c. ( frac{1}{x^{4}} )
D. ( frac{1}{x^{3 / 2}} )
12
1239Which of the following figure represents the electric field lines due to the
combination of one positive and one negative charge?
( A )
в.
( c )
D.
12
1240Four charges are kept at the corners of a
square ( A B C D ) as shown. The force on a
positive charge placed at the centre of
the square is
( A )
B. Along diagonal ACC
c. Along diagonal BD
D. perpendicular to side AB
12
1241( A ) and ( B ) are two points on the axis and the perpendicular bisector respectively of an electric dipole. A and B are far away from the dipole and at equal distances from it. The potentials at ( A )
and ( mathrm{B} ) are ( V_{A} ) and ( V_{B} ) respectively. Then
A. ( V_{A}=V_{B}=0 )
в. ( V_{A}=2 V_{B} )
( mathbf{c} cdot V_{A} neq 0, V_{B}=0 )
D. ( V_{A} neq 0, V_{B} neq 0 )
12
1242Electric charge is due to the loss or gain
of
A. protons
B. neutrons
c. electrons
D. none of these
12
1243The field potential inside a charged ball of radius ( mathrm{R} ) and centre at o depends only
on distance from its center as ( V(r)= )
( boldsymbol{alpha} boldsymbol{r}^{2}+boldsymbol{beta} ) when ( boldsymbol{alpha}, boldsymbol{beta} ) are ( + ) ve constant
now choose correct options
A . electric field inside the ball ( E_{r}=-2 alpha r )
B. electric flux passing through an imaginary sphere of radius r centre at 0 will be ( -2 pi alpha r^{4} )
C. volume charge density p(r) inside ball is ( -6 varepsilon_{0} alpha )
D. electric energy of charged ball will be ( frac{48}{5} pi varepsilon_{0} alpha^{2} R^{5} )
12
1244Show that no translator forces act on an
electric dipole held in uniform electric
field.
12
1245The given graph shows variation (with
distance r from center) of :
A. Electric field of a uniformly charged sphere
B. potential of a uniformly charged spherical shell
C. potential of a uniformly charged sphere
D. Electric field of a uniformly charged spherical shell
12
1246( A B C ) is a right angled triangle. Calculate
the magnitude of force on charge – ( Q )
12
1247the point ( P, ) the flux of the electric field
through the closed surface:
A. will remain zero
B. will becomes positive
c. will become negative
D. will become undefined
12
1248A solid metal sphere of radius ( boldsymbol{R} ) has a
charge ( +2 Q . ) A hollow spherical shell of
radius ( 3 R ) placed concentric with the
first sphere has net charge – ( boldsymbol{Q} )
A. The electric field between the spheres at a distance ( r ) from the centre of the inner sphere at ( R<r<2 R ) is
( frac{Q}{2 pi epsilon_{0} r^{2}} )
3. The potential difference between the spheres is ( frac{Q}{3 pi epsilon_{0} R} )
c. The final distribution of charges if the spheres are joined by a conducting wire is zero on both inner and outer surfaces of the outer sphere
( D )
If the inner sphere is earthed, the charge on it is
12
1249Mid way between the two equal and similar charges, we placed the third equal and similar charge. Which of the following statements are correct, concerned to the equilibrium along the line joining the charges?
A. The third charge will experience a net force inclined to the line joining the charges.
B. The third charge is in a stable equilibrium.
c. The third charge is in an unstable equilibrium.
D. The third charge will experience a net force perpendicular to the line joining the charges.
12
1250The displacement of a charge ( Q ) in the electric field ( boldsymbol{E}=boldsymbol{e}_{1} hat{boldsymbol{i}}+boldsymbol{e}_{2} hat{boldsymbol{j}}+boldsymbol{e}_{3} hat{boldsymbol{k}} ) is
( hat{boldsymbol{r}}=boldsymbol{a} hat{mathbf{1}}+boldsymbol{b} hat{boldsymbol{j}} . ) The work done is-
A ( Qleft(a e_{1}+b e_{2}right) )
() ( aleft(a_{1}+b_{2}right)+b_{2}+b_{2} )
в. ( Q sqrt{left(a e_{1}right)^{2}+left(b e_{2}right)^{2}} )
c. ( Qleft(e_{1}+e_{2}right) sqrt{a^{2}+b} )
D. ( Q(sqrt{e_{1}^{2}+e_{2}^{2}})(a+b) )
12
1251The number of electrons present in
( -1 C ) of charge is:
A ( cdot 6 times 10^{18} )
B . ( 1.6 times 10^{19} )
( c cdot 6 times 10^{19} )
D. ( 1.6 times 10^{18} )
12
1252An electric dipole is placed at the centre
of a sphere. Mark the correct answers:
This question has multiple correct options
A. The flux of the electric field through the sphere is zero.
B. The electric field is zero at every point of the sphere.
C. The electric potential is zero everywhere of the sphere.
D. The electric potential is zero on a circle on the surface.
12
1253Three concentric conducting spherical shells of radii ( boldsymbol{R}, 2 boldsymbol{R} ) and ( boldsymbol{3} boldsymbol{R} ) carry
charges ( Q,-2 Q ) and ( 3 Q, ) respectively. Compute the electric field at ( r=frac{5}{2} R )
( A )
B.
( c )
D.
12
1254Electric lines of forces.
A. May form closed path
B. Must form closed path
C. May be discontinuous
D. Both (a) and
(c) are correct
12
1255A body has a charge of ( -2 mu C ). If it has
( 2.5 times 10^{13} ) protons, then how many
electrons the body has?
A ( cdot 1.25 times 10^{13} )
B. ( 2.5 times 10^{13} )
c. ( 3.75 times 10^{13} )
D. None of these
12
1256The electric field at a point ( 2 mathrm{cm} ) from an infinite line charge of linear charge density ( 10^{-7} mathrm{cm}^{-1} ) is?
A ( cdot 4.5 times 10^{4} N C^{-1} )
B. ( 9 times 10^{4} N C^{-1} )
c. ( 9 times 10^{2} N C^{-1} )
D. ( 18 times 10^{4} N C^{-1} )
12
1257In conductors electrons can flow
because their
A . ions are free
B. electrons are free and mobile
c. protons are free
D. negative ions are free
12
1258Derive an expression for intensity of electric field at a point broadside
position or an equatorial line of an electric dipole.
12
1259What is the work done in moving a test charge ( q ) through a distance ( 4 mathrm{cm} ) along the equatorial axis of an electric dipole?
A . 4
B. 40
( c )
D.
12
1260The imaging drum of a photocopier is positively charged to attract negatively
charged particles of toner. Near the surface of the drum, its electric field
has magnitude ( 1.4 times 10^{5} N C^{-1} . ) A toner
particle is to be attached to the drum with a force that is 10 times the weight of the particle. Assume toner particles are made of carbon ( _{6}^{12} C ) Find charge to mass ratio of the charged toner particle :
A ( cdot 7.0 times 10^{-4} mathrm{Ckg}^{-1} )
В. ( 7.0 times 10^{-3} mathrm{Ckg}^{-1} )
C. ( 7.0 times 10^{-5} mathrm{Ckg}^{-1} )
D. ( 7.0 times 10^{-6} mathrm{Ckg}^{-1} )
12
1261So that the torque acting on it is maximum.12
1262A particle A having a charge of ( 5.0 times )
( 10^{-} 7 C ) is fixed in a vertical wall. ( A )
second particle ( B ) of mass 100 g and having equal charge is suspended by a
silk thread of length ( 30 mathrm{cm} ) above the
particle A. Find the angle of thread with
the vertical when it stays in
equilibrium.
12
1263Figure shows the electric field lines
around three point charges ( A, B ) and ( C )
Which charge has the largest
magnitude then?
( mathbf{A} cdot A )
B. ( B )
( c cdot C )
D. ( B ) and ( C ) have equal magnitude
12
1264Establish the formula for electric field
intensity at a point on the axis of an electric dipole.
12
1265Two spheres having same radius and mass are suspended by two strings of equal length from the same point in such a way that their surfaces touch
each other. On depositing charge ( 2 times ) ( 10^{-6} C ) on them they repel each other in
such a way that in equilibrium the angle between their strings becomes
( 60^{circ} . ) If the distance from the point of
suspension to the centre of the sphere is ( 10 mathrm{cm} . ) Find the mass of each sphere.
( left(boldsymbol{K}=mathbf{9} times mathbf{1 0}^{mathbf{9}} boldsymbol{S} boldsymbol{I} quad text { and } quad boldsymbol{g}=mathbf{1 0 m s}^{-1}right) )
A. ( 0.6235 k g )
в. ( 0.3117 k g )
c. ( 0.1559 k g )
D. ( 1.2468 k g )
12
1266An electric dipple has dipple moment
( 4 times 10^{-11} ) and the two charges have
magnitudes 4 nC each. Calculate the electric field due to the dipole
i) At a point on the axis at a distance ( 0.01 mathrm{m} ) from one of the charges and
ii) At a point on the perpendicular bisector at a distance ( 0.02 mathrm{m} ) from the
middle point.
12
1267Find the orbital magnetic dipole moment of the electron in a hydrogen
atom
12
1268A hollow conducting sphere has a net
charge of ( +Q . ) There are four labeled
points all on the inside of the sphere, as
shown above. Points A through D are
ocated progressively closer to the
center of the sphere.
Which point has the largest magnitude
of electric field?
A. Point A
B. Point B
( c . ) Point ( c )
D. Point D
E. All points have the ( d )
ie
12
1269A hollow conducting sphere is placed in
an electric field produced by a point
charge as shown. Let ( V_{A}, V_{B}, V_{C} ) be the
electric potentials at points ( A, B, C )
respectively and ( V_{0} ) is the potential at
centre 0 due to induced charge on shell.
This question has multiple correct options
A ( . V_{0}=0 )
В. ( V_{A}>V_{B}>V_{C} )
( mathbf{c} cdot V_{4}=V_{B}=V_{O} )
( mathbf{D} cdot V_{A}<V_{B}<V_{C} )
12
1270Three charges ( -mathbf{q}_{1},+mathbf{q}_{2} ) and ( -mathbf{q}_{3} ) are
placed as shown in the figure. The ( x )
component of the force on ( -q_{1} ) is proportional to:
A ( cdot frac{mathrm{q}_{2}}{mathrm{b}^{2}}-frac{mathrm{q}_{3}}{mathrm{a}^{2}} cos theta )
B. ( frac{mathrm{q}_{2}}{mathrm{b}^{2}}+frac{mathrm{q}_{3}}{mathrm{a}^{2}} sin theta )
c. ( frac{mathrm{q}_{2}}{mathrm{b}^{2}}+frac{mathrm{q}_{3}}{mathrm{a}^{2}} cos theta )
D. ( frac{mathrm{q}_{2}}{mathrm{b}^{2}}-frac{mathrm{q}_{3}}{mathrm{a}^{2}} sin theta )
12
1271If ( V_{0} ) be the potential at origin in an electric field ( overrightarrow{boldsymbol{E}}=boldsymbol{E}_{boldsymbol{x}} hat{boldsymbol{j}}+boldsymbol{E}_{boldsymbol{y}} hat{boldsymbol{j}}, ) then the
potential at point ( boldsymbol{P}(boldsymbol{x}, boldsymbol{y}) ) is
( mathbf{A} cdot V_{0}+x E_{x}+y E_{y} )
B. ( V_{0}+x E_{x}-y E_{y} )
C ( . V_{0}-x E_{x}-y E_{y} )
D. ( sqrt{left(x^{2}+y^{2}right)} sqrt{E_{x}^{2}+E_{y}^{2}}-V_{0} )
12
1272A cube is arranged such that its length, breadth, height are along ( X, Y ) and ( Z )
directions. One of its corners is situated
at the origin. Length of each side of the
cube is ( 25 mathrm{cm} ). The components of electric field are ( E_{x}=400 sqrt{2} N / C, E_{y}=0 ) and
( E_{Z}=0 ) respectively. The flux coming out
of the cube at one end, whose plane is
perpendicular to ( X ) axis, will be:
( mathbf{A} cdot 25 sqrt{2} N m^{2} / C )
( mathbf{B} cdot 5 sqrt{2} N m^{2} / C )
( mathbf{c} cdot 250 sqrt{2} N m^{2} / C )
D. ( 25 mathrm{Nm}^{2} / mathrm{C} )
12
Let ( left[epsilon_{0}right] ) denote the dimensional formula
of the permittivity of vacuum and ( left[mu_{0}right] ) that of the permeability of vacuum. If ( mathrm{M} ) ( = ) mass, ( L= ) length, ( T= ) time, and ( l= ) electric current, then
This question has multiple correct options
A ( cdotleft[epsilon_{0}right]=M^{-1} L^{-3} T^{2} I^{2} )
B . ( left[epsilon_{0}right]=M^{-1} L^{-3} T^{4} I^{2} )
c. ( left[mu_{0}right]=M L T^{-2} I^{-2} )
D. ( left[mu_{0}right]=M L^{2} T^{-1} I )
12
1274A point charge ( q ) is located at the centre of a thin ring of radius ( R ) with uniformly
distributed charge -q. Find the magnitude of the electric field strength vector at the point lying on the axis of the ring at a distance ( x ) from its centre
if ( x>>R )
12
1275If the dipole of moment ( 2.57 times )
( 10^{-17} mathrm{C} . mathrm{m} ) is placed into an electric
field of magnitude ( 3.0 times 10^{4} N / C ) such
that the fields lines are aligned at ( 30^{circ} ) with the line joining the dipole, what torque will act on the dipole?
A. ( 7.7 times 10^{-13} mathrm{Nm} )
B . ( 3.855 times 10^{-13} mathrm{Nm} )
( mathbf{c} cdot 3.855 times 10^{-15} mathrm{Nm} )
D. ( 7.7 times 10^{-15} mathrm{Nm} )
12
1276Which of the following is not a property
of charge?
B. Quantization
c. continuity
D. conservation
12
1277Who established that electric charge is quantised?
A. J.J. Thomson
B. William Crookes
c. R.A Millikan
D. Wilhelm Rontgen
12
1278Water from a tap, maintained at a constant potential ( V ), is allowed to fall by drops of radius ( r ) through a small hole into a hollow conducting sphere of radius R standing on an insulating stand until it fills the entire sphere. Find the potential of the hollow conductor after it is completely filled with water.12
1279The electric field in a region is radially
out ward with magnitude ( boldsymbol{E}=boldsymbol{A} boldsymbol{r} ). Find
the charge contained in a sphere of
radius ( 20 c m . ) Given ( A=100 V m^{-2} )
12
1280Quantisation of charge implies:
A. charge cannot be destroyed
B. charge exists on particles
C. there is a minimum permissible charge on a particle
D. charge, which is a fraction of a charge on an electron is not possible
12
1281When a charged balloon is brought near a charged silk thread, the two bodies
A. Repel each other
B. Attract each other
c. Neither attract nor repel
D. None of the above
12
1282Force of attraction between two point charges ( Q ) and ( -Q ) separated by ( d )
meter is ( F_{e} . ) When these charges are
placed two identical sphere of radius ( R=0.3 d ) whose centries are ( d ) meter
apart the force of attraction between
them is
A. Greater than ( F_{e} )
B. Equal to ( F_{e} )
c. Less than ( F_{e} )
D. None of these
12
axis. What would be the direction of
force on a positive test charge located
at the origin?
( mathbf{A} )
B.
( c )
( D )
12
1284A point charge is brought in an electric field. The electric field at a nearby point:
This question has multiple correct options
A. Will increase if the charge is positive
B. Will decrease if the charge is negative
c. May increase if the charge is positive
D. May decrease if the charge is negative
12
1285Electrically charged drops of mercury fall from an altitude ( h ) into a spherical metal vessel of radius R. There is a
small opening in the upper part of the vessel. The mass of each drop is ( mathrm{m} ), and the charge on the drop is Q. What will be
the number n of the last drop that can
still enter the sphere?
12
1286The intensity of an electric field at some point distant ( r ) from the axis of infinity long pipe having charged per unit length as q will be:
A. Proportional to ( r^{2} )
B. Proportional to ( r^{3} )
c. inversely proportional to ( r )
D. inversely Proportional to ( r^{2} )
12
1287Electric charges -q, -q, -q and 3q are
placed at the corners of a square ABCD
of length/as shown in figure. The magnitude of electric dipole moment of
the system is
( A cdot sqrt{2 q} )
B. 9
( c cdot 2 q )
D. ( 2 sqrt{2} q l )
12
1288The graph below shows the “x-direction”
position of a charged particle flying
around in space and accelerating due
only to some electric field.

During which time interval is the force
on the particle in the x-direction
greatest?
( mathbf{A} cdot 5 ) to 6 seconds
B. 6 to 7 seconds
( c .7 ) to 8 seconds
D. 8 to 9 seconds
E. 10 to 11 seconds

12
1289Consider an infinite line charge having uniform linear charge density and
passing through the axis of a cylinder. What will be the effect on the flux
passing through the cylinder if the
portions of the line charge outside the
cylinder is removed.
A. decreases
B. increases
c. remains same
D. cannot say
12
1290The potential at 0 is :
A. zero
В ( cdot frac{q}{4 pi epsilon_{0}}left[frac{1}{r}-frac{1}{R_{1}}+frac{1}{R_{2}}right] )
( ^{mathbf{C}} cdot frac{q}{4 pi epsilon_{0}}left[frac{1}{r}-frac{1}{R_{1}}right] )
D. None of these
12
1291Consider a thin spherical shell of radius R with its center at the origin, carrying uniform positive surface charge density. The variation of the magnitude
of the electric field and the electric
potential ( V(r) ) with the distance ( r ) from the center, is best represented by which
( operatorname{graph} )
( A cdot A )
B. B
( c . c )
( D )
12
1292An electric dipole of length ( 2 mathrm{cm}, ) when placed with its axis making an angle of ( 60^{circ} ) with a uniform electric field,
experiences a torque of ( 6 sqrt{3} mathrm{Nm} ) Calculate the potential energy of the dipole, if it has a charge of ( pm 2 mathrm{nC} )
12
1293What will be the magnitude of torque on an electric dipole having dipole moment of ( 4 times 10^{-9} mathrm{cm} ) placed in a uniform
electric field of intensity of ( 5 times )
( 10^{4} N C^{-1} ) making an angle ( 180^{circ} ) with
the field.
A ( cdot 10^{-4} N-m )
В. ( 2 times 10^{-4} N-m )
( c .0 ) (zero)
D. ( 10^{-6} N-m )
12
1294The electrostatic force between two
point charges ( q_{1} ) and ( q_{2} ) at separation ‘ ( r^{prime} ) is given by ( F=frac{K q_{1} q_{2}}{r^{2}} . ) The constant ( K )
A. depends on the system of units only
B. depends on the medium between the charges only.
c. depends on both the system of units and the medium between the charges.
D. is independent of both the system of units and the medium between the charges
12
1295When the disc of gold leaf electroscope is touched with positively charged glass rod the charge on the leaves of gold leaf electroscope is :
A. positive
B. negative
c. neutral
D. none of these
12
1296Two uncharged bodies when rubbed
against each other get charged. This is known as
A. Charging by conduction
B. Charging by friction
c. charging by induction
D. Charging by convection
12
1297Poor conductors of electricity is/are:
A. Silver
B. Aluminium
c. Pure water
D. copper
12
1298A charge of ( 5 times 10^{-10} C ) is given to a
metal cylinder of length ( 10 mathrm{m}, ) placed in air. The electric intensity at a distance of ( 0.2 mathrm{m} ) from its axis is :
A. ( 4.5 vee / ) m
B. ( 45 mathrm{V} / mathrm{m} )
c. ( 450 mathrm{V} / mathrm{m} )
D. ( 100 mathrm{v} / mathrm{m} )
12
1299A uniform electric field ( boldsymbol{E}=mathbf{2} times )
( 10^{3} N C^{-1} ) is acting along the positive ( x )
axis. The flux through the same square if the line normal to tis plane makes a
( 60^{circ} ) angle with the ( x ) -axis is
( begin{array}{lll}text { A. } 30 N & C^{-1} m^{2}end{array} )
B. ( 10 N quad C^{-1} m^{2} )
( begin{array}{lll}c cdot 20 N & C^{-1} m^{2} & ^{2}end{array}^{C^{2}} )
D. ( 25 N quad C^{-1} m^{2} )
12
1300On to a sphere of radius ( boldsymbol{R} / 2 ) and
density ( rho_{2} ) with centre at ( C_{2} ) a second
solid sphere is moulded with density ( rho_{1} )
radius ( R ) and centre ( C_{1} ). Find the force
experienced by a point mass ( m ) at point
( P ) at a distance ( y ) from the combination
as shown.
12
1301An electric dipole is placed at an angle
of ( 30^{circ} ) with an electric field of intensity
( 2 times 10^{5} N C^{-1} . ) It experiences a torque
of ( 4 N m . ) Calculate the charge on the
dipole if the dipole length is ( 2 mathrm{cm} ) :
( A cdot 8 m C )
в. ( 4 m C )
( c cdot 8 mu C )
D. ( 2 m C )
12
1302in which two infinitely long static line charges of constant positive line charge
density ( lambda ) are kept parallel to each other.
In their resulting electric field, point
charges ( boldsymbol{q} ) and ( -boldsymbol{q} ) are kept in
equilibrium between them. The point
charges are confined to move in the ( x )
direction only. If they are given a small
displacement about their equilibrium positions, then the correct statement(s) is (are)
A. Both charges execute simple harmonic motion.
B. Both charges will continue moving in the direction of their displacement
c. Charge ( +q ) executes simple harmonic motion while charge ( -q ) continues moving in the direction of its displacement.
D. Charge ( -q ) executes simple harmonic motion while charge ( +q ) continues moving in the direction of its displacement
12
1303A cylinder of radius ( R ) and length ( L ) is
placed in a uniform electric field ( boldsymbol{E} )
parallel to the cylinder axis. The total flux for the surface of the cylinder is given by :
( mathbf{A} cdot 2 pi R^{2} E )
в. ( frac{pi R^{2}}{E} )
c. ( frac{R}{E} )
D. zero
12
1304A balloon is blown up to a radius ( R ). It is
then has a positive charge ( +Q ) added to it. Air is then let out so that the radius
reduces to ( R / 2 ), however, the net charge remains the same.
How is the charge density affected by the reducing of the radius?
A. The charge density increases.
B. The charge density is unaffected.
c. The charge density decreases.
D. There is not enough information to answer the question
12
1305An electric dipole of moment ( vec{p} ) is placed normal to the lines of force of electric intensity ( vec{E} ), then work done in
deflecting it through an angle of ( 180^{circ} ) is:
A ( . p E )
в. ( +2 p E )
c. ( -2 p E )
D. zero
12
1306A charge is distributed over two
concentric hollow spheres of radii ( boldsymbol{R} ) and ( r, ) where ( R>r, ) such that the
surface densities of charges are equal
( ( sigma ) ). What is the potential at their
common centre?
A ( cdot frac{sigma}{varepsilon_{0}}(R+r) )
В ( cdot frac{varepsilon_{0}}{sigma}(R+r) )
c. ( frac{sigma}{varepsilon_{0}} R )
D. ( frac{sigma}{varepsilon_{0}} r )
12
1307A charge ( ^{prime} boldsymbol{q}^{prime} ) is placed at the centre of the line joining two equal charges. The system will be in equilibrium if ( q ) is
equal to
A. ( -Q / 2 )
в. ( -Q / 4 )
( c .-4 Q )
D. ( +Q / 2 )
12
1308Correct the given statements:
Materials which allow electric current
to pass through them are called Insulators.
12
1309A point charge is placed at the corner of a cube. The electric flux through the
( A cdot frac{q}{8 c_{0}} )
B. ( frac{q}{varepsilon_{0}} )
( c cdot frac{q}{24 c} )
( D cdot frac{q}{12 varepsilon 0} )
12
1310When a glass rod is rubbed with silk
cloth, it acquires positive charge because:
A. electrons are added to it
B. electrons are removed from it
c. protons are added to it
D. protons are removed from it
12
1311A charged oil drop is suspended in
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 ( =mathbf{9 . 9} times )
( left.10^{-15} mathrm{kg} text { and } g=10 m / s^{2}right) )
A . ( 3.3 times 10^{-18} mathrm{C} )
B. ( 3.2 times 10^{-18} mathrm{C} )
c. ( 1.6 times 10^{-18} mathrm{C} )
D. ( 4.8 times 10^{-18} mathrm{C} )
12
1312The dimensions of an atom are of the
order of an Angstrom. Thus there must be large electric fields between the protons and electrons. Why then is the electrostatic field inside a conductor
zero?
12
13131000 small water drops each of radius
( r^{prime} ) and charge ( ^{prime} q^{prime} ) coalesce together to one spherical drop. The potential of the big drop is larger than that of the smaller drops by a factor of:
A. 1000
в. 100
c. 10
D.
12
1314Two charges when kept at a distance of ( 1 m ) apart in vacuum have some force of
repulsion. If the force of repulsion between these two charges be same, when placed in an oil of dielectric
constant ( 4, ) the distance of separation is :
( mathbf{A} cdot 0.25 m )
в. ( 0.4 m )
( c .0 .5 m )
D. ( 0.6 m )
12
1315What happens when two straws are individually rubbed with separate sheets of paper and are brought near to each other?
A. The straws attract each other
B. The straws repel each other
c. The straws remain indifferent of each other
D. Either A or B
12
1316A conducting ball is given a certain charge and fixed at point ( P . ) An another
charge of mass ( 1 g m ) and charge ( 20 mu C )
when kept at ( Q(3 m, 9 m) ) starts moving with acceleration ( overrightarrow{boldsymbol{a}}=(1.08 hat{boldsymbol{i}}+ )
1.44 ( hat{boldsymbol{j}} ) ) ( boldsymbol{m} boldsymbol{s}^{-2} ). The potential at ( boldsymbol{Q} ) is ( +mathbf{7 2 0} )
volt. Calculate
(a) charge given to ball
(b) position of the ball
( mathbf{A} cdot 6.4 times 10^{-7} C(mathrm{b})(-1.8 m, 4 m) )
B . ( 6.4 times 10^{-7} C(text { b ) }(-2.8 m, 2 m) )
C ( .7 .4 times 10^{-7} C(mathrm{b})(-1.8 m, 2 m) )
D. ( 6.4 times 10^{-7} C ) (b) ( (-1.8 m, 2 m) )
12
1317The bob of a pendulum of mass ( mathrm{m} ) and length I and a charge of q is in the rest position in a uniform horizontal electric field of E. The tension in the string of the
pendulum is :
A . ( m g )
в. ( q E )
c. ( left[(m g)^{2}+(q E)^{2}right]^{1 / 2} )
D ( cdotleft[(m g)^{2}+(q E)^{2}right]^{1 / 4} )
12
1318Charges ( Q ) each are placed at each of two opposite corners of a square. Charges ( q ) each are placed at each of
the other two corners. Find the relation
between ( q ) and ( Q, ) when the net force on
Q is zero.
A ( cdot_{q}=-frac{3 Q}{2 sqrt{2}} )
в. ( _{q}=+frac{Q}{2 sqrt{2}} )
c. ( _{q=-frac{Q}{sqrt{2}}} )
D. ( _{q}=-frac{Q}{2 sqrt{2}} )
12
1319Three infinitely charged sheets are kept parallel to ( x-y ) plane having charge
densities as shown. Then the value of
electric field at ( ^{prime} boldsymbol{P}^{prime} ) is:
A ( frac{-4 sigma}{epsilon_{0}} )
в. ( frac{4 sigma}{epsilon_{0}} )
c. ( frac{-2 sigma}{epsilon_{0}} )
( D cdot frac{2 sigma}{epsilon_{0}} )
12
1320At a certain locations, the strength of the electric field is ( 30.0 mathrm{N} / mathrm{C} ). A charge of ( 3.00 mathrm{C} ) is placed at this location. How much force does this charge experience due to the electric field?
A. 90.0 N
B. 10.0
c. ( 0.100 mathrm{N} )
D. 270 N/C
E. ( 3.33 mathrm{N} / mathrm{C} )
12
1321Two charges ( Q ) and ( -2 Q ) are placed at some distance. the locus of points in
the plane of the charges where the potential is zero will be
A. Straight line
B. Circle
c. Parabola
D. ellipse
12
1322Electric switches and
appliances should be tested only with
A. Right hand
B. Left hand
c. Both hands
D. Electric tester
12
1323If ( 10^{20} ) electrons are removed from a
conductor. The nature and magnitude of the charge developed on it is :
( mathbf{A} cdot+16 C )
в. ( -16 C )
( c cdot+10 C )
D. ( -10 C )
12
1324In a region an electric field ( mathrm{E}=15 mathrm{N} / mathrm{C} )
making an angle of ( 30^{circ} ) with the horizontal plane is present. A ball having charge ( 2 mathrm{C}, ) mass ( 3 mathrm{kg} ) and coefficient of restitution with ground
( 1 / 2 ) is projected at an angle of ( 30^{circ} ) with the horizontal in the direction of electric field with speed ( 20 mathrm{m} / mathrm{s} ), the horizontal distance travelled by ball from first drop to the second drop is equal to ( 10 x sqrt{3} m ) The value of ( x ) is:
12
1325charge distribution will be:
( A )
B.
( c )
D.
12
1326If a body is charged by rubbing it, its weight
A. Remains precisely constant
B. Increases slightly
c. Decreases slightly
D. May increase or decrease slightly
12
1327If ( I_{1} ) and ( I_{2} ) are the magnitudes if
inclined current in the cases I and II
respectively, then.
( mathbf{A} cdot I_{1}=I_{2} )
( mathbf{B} cdot I_{1}>I_{2} )
( mathbf{C} cdot I_{1}<I_{2} )
D. Nothing can be said
12
1328When a plastic comb rubbed on hair is brought near bits of paper, it attracts them because:
A. The comb and the paper get similarly charged.
B. They get oppositely charged.
c. The paper bits are very light.
D. None of these
12
1329The exact equation of motion of the
( ^{mathbf{A}} cdot_{m} frac{d^{2} x}{d t^{2}}=–frac{k 2 Q q x}{left(x_{0}^{2}+R^{2}right)^{3 / 2}} )
B. ( quad m frac{d^{2} x}{d t^{2}}=–frac{k Q q x}{left(x_{0}^{2}+R^{2}right)^{3 / 2}} )
( ^{mathbf{C}} cdot quad m frac{d^{2} x}{d t^{2}}=–frac{k 2 Q q x}{left(x_{0}^{2}-R^{2}right)^{3 / 2}} )
( ^{mathrm{D}} cdot quad m frac{d^{2} x}{d t^{2}}=–frac{k Q q x}{left(x_{0}^{2}-R^{2}right)^{3 / 2}} )
12
1330A ( 1 mathrm{kg} ) ball is suspended in a uniform electric field with the help of a string fixed to a point. The ball is given a charge ( sqrt{5} ) coulomb and the string
makes an angle ( 37^{0} ) with the vertical in
the equilibrium position. In the equilibrium position the tension is double the weight of the ball. Find the magnitude of the electric field in ( mathrm{N} / mathrm{C} )
( A cdot 6 )
B. 3
( c cdot 2 )
D. 5
12
1331Aluminium metal is:
A. magnetic substance
C . good conductor of electricity
12
1332Gases begin to conduct electricity at
low pressure because
A. the lectrons in atoms can move freely at low pressures
B. atoms break up into electrons and protons.
C. colliding electrons can acquire higher kinetic energy due to increased mean free path leading to ionization of atoms.
D. at low pressure gases turn into plasma.
12
1333If a water particle of mass ( 10 mathrm{mg} ) and having a charge of ( 1.5 times 10^{-6} C ) stays
suspended in a room, then the
magnitude and direction of electric field in the room is
A. ( 15 N / C ), vertically upwards
B. 15 N/C, vertically downwards
c. ( 65.3 mathrm{N} / mathrm{C} ), vertically upwards
D. ( 65.3 mathrm{N} / mathrm{C} ), vertically downwards
12
1334If the flux of the electric field through a closed surface is zero,
This question has multiple correct options
A. the electric field must be zero everywhere on the surface
B. the electric field may be zero everywhere on the surface
c. the charge inside the surface must be zero
D. the charge in the vicinity of the surface must be zerç
12
1335Three point charges ( -q, q ) and ( Q ) are arranged as given in figure:

If ( d ) is distance from centre of ( -q ) and ( +boldsymbol{q} ) to ( boldsymbol{Q} ) and ( boldsymbol{d}>>>boldsymbol{a}, ) then the
potential energy of given system is:
[
mathbf{q}
]
( A )
[
left(frac{k q Q a}{d^{2}}right)
]
в.
[
left(frac{+k q^{2}}{a}+frac{k q Q a}{d^{2}}right)
]
c.
[
left(frac{-k q^{2}}{a}+frac{k q Q a}{2 d^{2}}right)
]
D.
[
left(frac{-k q^{2}}{a}+frac{k q Q a}{d^{2}}right)
]

12
1336A thin spherical conduction shell of radius R has a charge q. another charge ( mathrm{Q} ) is placed atthe centre of the shell. The electrostatic potential at a point ( mathrm{P} ) at a distance ( mathrm{R} / 2 ) from thecentre of the shell is
A ( cdot frac{2 Q}{4 pi varepsilon_{0} mathrm{R}} )
в. ( frac{2 Q}{4 pi epsilon_{0} mathrm{R}}-frac{2 mathrm{q}}{4 pi varepsilon_{0} mathrm{R}} )
c. ( frac{2 mathrm{Q}}{4 pi epsilon_{6} mathrm{R}}+frac{mathrm{q}}{4 pi varepsilon_{0} mathrm{R}} )
D. ( frac{(mathrm{q}+mathrm{Q})}{4 pi varepsilon_{0}} frac{2}{mathrm{R}} )
12
1337A gold coin has a charge of ( +10^{-4} C . ) The
number of electrons removed from it is:
A ( cdot 10^{6} )
В. ( 625 times 10^{12} )
c. ( 1.6 times 10^{-25} )
D. ( 1.6 times 10^{13} )
12
1338If ( F_{g} ) and ( F_{e} ) are gravitational and electrostatic forces between two
electrons at a distance ( 0.1 m ) then
( boldsymbol{F}_{boldsymbol{g}} / boldsymbol{F}_{e} ) is in the order of
A ( cdot 10^{43} )
B . ( 10^{-43} )
( mathbf{c} cdot 10^{35} )
D. ( 10^{-35} )
12
1339Which of the following instruments is used for detecting electric charge?
A. Ammeter
B. Galvanometer
c. Electroscope
D. None of the above
12
1340An electric dipole is placed at the centre
of a sphere. Mark the correct options:
A. The electric field is zero at every point of the sphere
B. The flux of the electric field through the sphere is nonzero
c. The electric field is zero on a circle on the sphere
D. The electric field is not zero anywhere on the sphere
12
1341Two concentric spheres kept in air have radii ‘R’ and ‘r’. They have similar charge
and equal surface charge density’ ( sigma^{prime} ) The electric potential at their common
centre is. ( left(epsilon_{0}= ) permittivity of free right. space ( ) )
A ( cdot frac{sigma(R+r)}{epsilon_{0}} )
в. ( frac{sigma(R-r)}{epsilon_{0}} )
c. ( frac{sigma(R+r)}{2 epsilon_{0}} )
D. ( frac{sigma(R+r)}{4 epsilon_{0}} )
12
1342Three charged particles are in equilibrium under their electrostatic forces only. which of the following statements is true for the system. This question has multiple correct options
A. the particles have the same charge
B. all the charges cannot have the same magnitude
c. all the charges cannot have the same sign
D. the equilibrium is unstable
12
1343A woolen cloth when rubbed against
plastic object acquires
charge.
A. Sometimes positive and sometimes negative
B. Negative
c. Positive
D. None of the these
12
1344Two metallic spheres of radii ( 1 mathrm{cm} ) and
( 3 c m ) are given charges of ( -1 times 10^{-2} C )
and ( 5 times 10^{-2} C, ) respectively. If these are
connected by a conducting wire, the final charge on the bigger sphere is-
A ( cdot 3 times 10^{-2} mathrm{C} )
B. ( 4 times 10^{-2} mathrm{C} )
c. ( 1 times 10^{-2} C )
D. ( 2 times 10^{-2} C )
12
1345An electric dipole placed with its axis in the direction of a uniform electric field experiences:
( A ). a force but not torque
B. a torque but no force
c. a force as well as a torque
D. neither a force nor a torque
12
1346In charging by conduction, the charged
object
A. ends up oppositely charged to the object used to charge it.
B. ends up similarly charged to the object used to charge it.
C. discharges the object used to charge it, completely.
D. discharges the object used to charge it, to some extent
12
1347A proton of mass ( m ) charge ( e ) is released from rest in a uniform electric field of
strength ( E . ) The time taken by it to travel a distance ( d ) in the field is :
A ( cdot sqrt{frac{2 d e}{m E}} )
в. ( sqrt{frac{2 d m}{E e}} )
c. ( sqrt{frac{2 d E}{m e}} )
D. ( sqrt{frac{2 E e}{d m}} )
12
two charges is represented by the field
lines also shown in the diagram.
What signs do the two charges have,
and which charge is stronger?
A. Charge 1 is positive, Charge 2 is negative and the stronger charge is Charge 1
B. Charge 1 is positive, Charge 2 is negative, and both charges have the same strength.
C. Charge 1 is negative, Charge 2 is positive, and the stronger charge is Charge 1
D. Charge 1 is negative, Charge 2 is positive, and both charges have the same strength.
E. Charge 1 is positive, Charge 2 is negative, and the stronger charge is Charge 2
12
1349Two tiny spheres, each of mass ( M, ) and
charges ( +boldsymbol{q} ) and ( -boldsymbol{q} ) respectively, are connected by a massless rod of length,
L. They are placed in a uniform electric field an an angle ( theta ) with the ( vec{E}left(theta=0^{circ}right) )
Calculate the minimum time in which
the dipole axis becomes parallel to the field line.
12
1350A positively charged rod is brought near the disc of a positively charged gold leaf electroscope. State your observation
A. Divergence increases.
B. Divergence decreases.
c. Divergence remains same
D. cant say
12
1351A particle that carries a charge ( -q ) is placed at rest in uniform electric field
( 10 N / C . ) It experiences a force and moves in a certain time ( t, ) it is observed to acquire a velocity ( 10 vec{i}-10 vec{j} mathrm{m} / mathrm{s} ). The
given electric field intersects a surface of area ( A m^{2} ) in the ( X ) -Z plane. Electric flux
through surface is:
в. ( 5 A N m^{2} / C )
c. ( sqrt{2} A N m^{2} / C )
( mathbf{D} cdot 2 sqrt{5} A N m^{2} / C )
12
1352When a body is negatively charged by
friction, it means
A. the body has acquired excess of electrons
B. the body has acquired excess of protons
C. the body has lost some electrons
D. the body has lost some neutrons
12
1353The potential of outer shell is
( A cdot frac{q}{32 pi epsilon 0^{a}} )
B. ( frac{q}{16 pi epsilon a} )
( c cdot frac{q}{8 pi cos ^{a}} )
( D cdot frac{q}{4 pi varepsilon a a} )
12
1354If a body is charged by rubbing it, its weight :
A. Remains precisely constant
B. Increase slightly
c. Decrease slightly
D. May increase slightly or may decrease slightly
12
1355A rectangular tank of mass ( m_{o} ) and charge ( Q ) over it is placed over a smooth horizontal floor. A horizontal electric
field ( E ) exist in the region. Rain drops are falling vertically in the tank at the constant rate of ( n ) drops per second
Mass of each drop is m. Find velocity of ( operatorname{tank} ) as function of time.
12
1356Stat law of conservation of charges?12
1357What is the ratio of electric field
intensity at distance ( 5 mathrm{cm} ) to that at 10
( mathrm{cm} ) from a point charge ( Q ) in air?
A . 2: 1
B. 1: 2
c. 4: 1
D. 1: 4
12
1358When a body is charged, its mass:
A. increases
B. decreases
c. remains same
D. none of these
12
1359A charge ( Q ) is placed at the centre of the open end of a cylindrical vessel of radius ( R ) and height ( 2 R ) as shown in
figure. The flux of the electric field through the surface (curved surface ( + ) base) of the vessel is
A ( cdot frac{Q}{epsilon_{0}} )
в. ( frac{Q}{2 E_{0}}left(1+frac{1}{sqrt{2}}right) )
c. ( frac{Q}{4 epsilon_{0}} )
D. ( frac{Q}{sqrt{5} epsilon_{0}} )
12
1360An electric dipole when placed in a uniform electric field will have minimum
potential energy, if the angle between dipole moment and electric field is
A . zero
B. ( frac{pi}{2} )
( c . pi )
D. ( frac{3 pi}{2} )
12
1361A charge ( q ) is placed at the centre of the open end of cylindrical vessel. The flux of electric field through the surface of
the vessel is
A . 0
в. ( frac{q}{epsilon_{0}} )
c. ( frac{q}{2 epsilon_{0}} )
D. ( frac{2 q}{epsilon_{0}} )
12
1362Glass wool is a ….. conductor of
electricity.
A . goodd
c. very good
D. None of the above
12
1363Identify the conductors from the
following:
Eraser, paper, matchstick, copper wire, polythene
A . eraser
B. copper wire
c. paper
D. polythene
12
1364toppr
of the electric field and the electric
potential ( V(r) ) with the distance ( r ) from
the centre, is best represented by which
graph ?
( A )
( B )
( c )
( D )
12
1365The electric flux passing through a hemispherical surface of radius ( mathrm{R} )
placed in an electric field E with its axis parallel to the filed is :
( mathbf{A} cdot pi R^{2} E )
В. ( 2 pi R^{2} E )
c. ( 2 pi R E )
( mathbf{D} cdot 2 pi R^{3} E )
12
1366A cube of side ( 10 mathrm{cm} ) encloses a charge
of ( 0.1 mu C ) at its centre.What is the
number of lines of force through each
face of the cube
A ( cdot 1.13 times 10^{11} )
В. ( 1.13 times 10^{6} )
c. ( 1.13 times 10^{23} )
D. 1883
12
1367The above diagrams show the electric field lines of charged particles. Identify which of the following drawing represents field lines between two
parallel plates?
A. Drawing
B. Drawing II
c. Drawing III
D. Drawing IV
E. Drawing V
12
1368The specific charge of a proton is ( 9.6 times ) ( 10^{7} C / k g . ) The specific charge of an
alpha particle will be:
( mathbf{A} cdot 9.6 times 10^{7} C / k g )
B . ( 19.2 times 10^{7} C / k g )
( mathbf{c} cdot 4.8 times 10^{7} C / k g )
D. ( 2.4 times 10^{7} C / k g )
12
1369An electron and a proton equal momenta, enter a uniform magnetic filed at right angles to the field lines.
What will be the ratio of the radii of an
vature of three trajectories.
A . 1: 1
B. 1: 2
c. 2: 3
D. 3: 4
12
1370A charge ( q ) is located at the centre of a cube. The electric flux through any face is :
A ( cdot frac{pi q}{6left(4 pi varepsilon_{0}right)} )
в. ( frac{q}{6left(4 pi varepsilon_{0}right)} )
c. ( frac{4 pi q}{6left(4 pi varepsilon_{0}right)} )
D. ( frac{4 pi q}{frac{1}{6}left(4 pi varepsilon_{0}right)} )
12
1371toppr ( mathbf{G} )
the plates
As some of the oil evaporates, the
droplet loses mass and starts to
accelerate. Its charge remains constant.
In which direction does the droplet
accelerate, and which change needs to
be made to the separation of the plates in order to stop this acceleration?
separation of the direction of
acceleration
downwards
downwards
upwards decrease
D upwards increase
( A cdot A )
B. B
( c cdot c )
D. D
12
1372An electric dipole is placed in an electric
field generated by a point charge. Choose the correct option:
A. the net electric force on the dipole must be zero
B. the net electric force on the dipole may be zero
C. the torque on the dipole due to the field must be zero
D. the torque on the dipole due to the field is not equal to zero
12
1373You are provided with a negatively charged gold leaf electroscope. What is the effect on the gold leaves when a glass rod rubbed with silk is brought near the disc of electroscope?
A. Divergence increases
B. Divergence decreases
c. Divergence remains same
D. Can not be determined
12
1374There is an electric field ( overrightarrow{mathrm{E}}=frac{a x^{3} hat{i}+b y^{4} widehat{j}+c z^{2} widehat{k}}{a x^{4}+b y^{5}+c z^{3}} )
at any ( (x, y, z) ) coordinates in the space
except origin, Where a,b & c are constant.
Find the electrostatic flux passing
through a sphere of radius R whose
center is at the origin.
( mathbf{A} cdot pi R )
( mathbf{B} cdot 2 pi R )
( mathbf{c} .4 pi R )
D. Zero
12
1375The adjoining figure shows a negatively charged electroscope. If a negatively charged rod is brought close to, but not
touching, the knob, the two leaves will :
A. move closer together
B. move farther aparttt
c. not move at all
D. None of these
12
1376A mass of 1 kg carrying a charge of ( 2 C )
is accelerated through a potential of ( 1 mathrm{V} ) The velocity acquired by it is?
A ( cdot sqrt{2} m s^{-1} )
B . ( 2 m s^{-1} )
c. ( frac{1}{sqrt{2}} m s^{-1} )
D. ( frac{1}{2} m s^{-1} )
12
1377The region between two concentric
spheres of radii a and ( b(>a) )
contains volume charge density ( rho(r)= )
( C )
( boldsymbol{r} )
where ( C ) is a constant and ( r ) is the
radial distance, as shown in figure. A
point charge ( q ) is placed at the origin, ( r= )
O.Find the value of ( C ) for which the
electric field in the region between
the spheres is constant (i.e., r
independent)
12
1378The minimum charge on an object is:
A. 1 coulomb
B. 1 stat coulomb
C ( .1 .6 times 10^{-20} ) coulomb
D. ( 1.6 times 10^{-19} ) coulomb
12
1379What is the nature of electric charge?
A . only positive
B. only negative
c. positive and negative both
D. neutral.
12
1380Equal charges ( Q ) are placed at the four corners ( A, B, C ) and ( D ) of a square of
length ( a ). The magnitude of the force on
the charge at ( B ) will be
( ^{mathrm{A}} cdot frac{3 Q^{2}}{4 pi varepsilon_{0} a^{2}} )
В. ( frac{4 Q^{2}}{4 pi varepsilon_{0} a^{2}} )
c. ( frac{k Q^{2}}{a^{2}}left(frac{2 sqrt{2}+1}{2}right) )
D ( cdotleft(2+frac{1}{sqrt{2}}right) frac{3 Q^{2}}{4 pi varepsilon_{0} a^{2}} )
12
1381Find the electric field at a distance ( x )
from the centre inside the shell.
( mathbf{A} cdot E=0 )
в. ( quad E=frac{Q}{4 pi epsilon_{0} a^{2}} )
c. ( _{E}=frac{Q}{4 pi epsilon_{0} x^{2}} )
D. ( _{E}=frac{Q}{4 pi epsilon_{0}(a-x)^{2}} )
12
1382An electric dipole consists of charges
( pm 2.0 times 10^{-8} C ) separated by a distance
of ( 2.0 times 10^{-3} m ). It is placed near a
long line charge of linear charge density ( 4.0 times 10^{-4} C quad m^{-1} ) as shown in the
figure, such that the negative charge is
at a distance of ( 2.0 mathrm{cm} ) from the line
charge. The force acting on the dipole
will be
A. ( 7.2 N ) towards the line charge
B. ( 6.6 N ) away from the line charge
c. ( 0.6 N ) away from the line charge
D. ( 0.6 N ) towards the line charge
12
1383The particles which can be added to the nucleus of an atom, without changing properties, are called.
A. Neutrons
B. Electrons
c. Protons
D. None of these
12
1384An electric dipole when placed in a uniform electric field ( boldsymbol{E} ) will have a
minimum potential energy if the dipole moment makes the following angle with
( boldsymbol{E} )
( A )
В. ( pi / 2 )
c. zero
D. ( 3 pi / 2 )
12
1385Two small identical conducting balls ( A ) and ( mathrm{B} ) of charges ( +10 mu mathrm{C} ) and ( +30 mu mathrm{C} ) respectively, are kept at a separation of ( 50 mathrm{cm} . ) These balls have been connected by a wire for a short time. The final
charge on each of the balls ( A ) and ( B ) will
be:
A ( . ) 10 ( mu mathrm{C} ) and ( 30 mu mathrm{C} ), respectively
B. 20 muC on each ball
c. ( 30 mu mathrm{c} ) and ( 10 mu mathrm{C} ), respectively
D. -40 muC and 80 muC, respectively
12
1386Which statement best explains why a
rubber rod becomes negatively charged
when rubbed with fur?
A. The rubber that the rod is made of is a better insulator than fur.
B. The fur is a better insulator than the rubber.
C. Molecules in the rubber rod have a stronger attraction for electrons than the molecules in the fur.
D. Molecules in the fur have a stronger attraction for electrons than the molecules in the rubber rod.
12
body of mass ( mathrm{m} ) and charge ( mathrm{q} ) is placed
perpendicular to the centre of sqaure at
a distance ( h ) from the centre. Take the
distance between centre and vertices of
the sqaure to be ‘ ( a ) ‘. What should be the
value of ( Q ) in order that this body may be
in equilibrium?
A ( cdot pi varepsilon_{0} frac{m g}{2 h q}left(h^{2}+2 a^{2}right)^{3 / 2} )
B. ( pi varepsilon_{0} frac{m g}{h q}left(h^{2}+a^{2}right)^{3 / 2} )
c. ( pi varepsilon_{0} frac{2 m g}{h q}left(h^{2}+2 a^{2}right)^{3 / 2} )
P. ( quad frac{m g}{h q}left(h^{2}-a^{2}right)^{3 / 2} )
12
1388A positively charged rod is touched with the brass disc of a positively charged gold leaf electroscope. State the effect on divergence of the leaves.
A. Divergence increases
B. Divergence decreases
c. Divergence remains same
D. none
12
1389A charge ( Q ) is divided into two parts of ( q )
and ( Q-q . ) If the Coulomb repulsion
between them when they are separated, is to be maximum, the ratio of ( frac{Q}{q} ) should be:
A .2
в. ( 1 / 2 )
( c cdot 4 )
D. ( 1 / 4 )
12
1390The rod or stem of a gold leaf electroscope is made of
A. wood
B. Brass
c. Glass
D. Ebonite
12
1391A small isolated conductor has a large
positive charge.

What is true of the electric field and the
electric potential inside this conductor?
A . Electric Field inside Conductor – Electric Potential inside Conductor, large and positive – large and positive
B. Electric Field inside Conductor – Electric Potential inside Conductor, zero – zero
C. Electric Field inside Conductor – Electric Potential inside Conductor, zero – large and positive
D. Electric Field inside Conductor – Electric Potential inside Conductor, large and positive – zero
E. Electric Field inside Conductor – Electric Potential inside Conductor, large and positive – large and negative

12
1392Define one “Coulomb”‘ on the basis of
Coulomb’s law.
12
1393A charge ( Q ) is to be distributed on two
objects, ( A ) and ( B ). The values of the
charges on the objects are such that the force between the objects will be
maximum. The ratio ( Q_{A}: Q_{B} ) will be
A . 1: 1
B. 1: 2
c. 1: 3
D. 1: 4
12
1394The electric field ( vec{E} ) in the overlapped
region is
A. non-uniform
c. ( frac{p}{3 varepsilon_{0}} )
D. ( frac{-p}{3 varepsilon_{0}} )
12
1395Formula of coloumbs inverse square
law is (using electric charges), assume ( k=frac{1}{4 pi epsilon_{0}} )
A. ( F=q_{1} q_{2} d^{2} cdot K )
B. ( F=frac{q_{1} q_{2}}{K d^{2}} )
( ^{mathrm{c}} cdot_{F}=frac{sqrt{K} q_{1} q_{2}}{d^{2}} )
D. None of these
12
13966. A charged oil drop is suspended in a uniform field of
3 x 104 V/m so that it neither falls nor rises. The charge
on the drop will be (take the mass of the charge as
9.9 x 10-15 kg and g = 10 m/s)
(a) 3.3 x 10-18C (b) 3.2 x 10-18 C
(c) 1.6 x 10-18 C
(d) 408 x 1018 C
(AIEEE 2004)
12
1397The magnitude of electric field as a
function of the distance r inside the
sphere is given by :
( ^{mathbf{A}} cdot_{E}=frac{rho_{0}}{varepsilon}left[frac{r}{3}-frac{r^{2}}{4 R}right] )
B. ( quad E=frac{rho_{0}}{varepsilon}left[frac{r}{4}-frac{r^{2}}{3 R}right] )
( ^{mathrm{C}}=frac{rho_{0}}{varepsilon}left[frac{r}{3}+frac{r^{2}}{4 R}right] )
D. ( quad E=frac{rho_{0}}{varepsilon}left[frac{r}{4}+frac{r^{2}}{3 R}right. )
12
1398Which material is a best conductor?
A . silver
B. porcelain
c. rubber
D. gold
12
1399The electric field in a region of space is given by ( vec{E}=(hat{5} i+hat{2} j) N c^{-1} . ) The electric
flux due to this field through an area ( 2 m^{2} )
lying in the ( Y ) -Z plane in S.I. units is
A . 10
B. 20
c. ( 10 sqrt{2} )
2
D. ( 2 sqrt{29} )
12
1400Calculate the electric potential at the
center of the square in figure.
12
1401In instantaneous current in a metallic
wire is ( mathrm{i}=(5+10 mathrm{t}) mathrm{A} ) then find amount of
charge flown through it from ( t=2 s ) to ( t=3 s ) is
A . 100
B. 24C
c. ( 30 c )
D. 40C
12
1402Three large plates are arranged as shown. How much charge will flow
through the key ( K ) if it is closed?
( A cdot frac{5 Q}{6} )
в. ( frac{4 Q}{3} )
( c cdot frac{3 Q}{2} )
D. None of these
12
1403The figure shows three concentric metallic spherical shells. The outermost
shell has charged ( q_{2}, ) the innermost
shell has charged ( q_{1} ), and the middle shell is undercharged. The charge
appearing on the inner surface of the outermost shell is
A ( cdot(a) q_{1}+q )
[
q
]
B. ( (b) frac{q}{2} )
( c cdot(c)-q )
( D cdot(d) ) Zero
12
1404Define intensity of electric field at a
point. Derive an expression for the
electric field intensity due to a point charge.
12
1405Point charges each of magnitude ( Q ) are
placed at three corners of a square as shown in the diagram.

What is the direction of the resultant
electric field at the fourth corner?
A. ( O C )
в. ( O E )
( c . O D )
( D, O B )

12
1406Gases are good conductors of electricity
This question has multiple correct options
A . low pressure
B. high pressure
c. low temperature
D. high temperature
12
1407What will be the nature of charge on the metal paper clip of electroscope when a positively charged body is brought in contact with it?
A. Positive
B. Negative
c. Partially negative
D. None of the above
12
1408A given charge ( q ) is situated at a certain distance from a small electric dipole in the end on position experiences a force
F. If the distance of the charge is doubled, the force acting on the charge
will become:
A ( .2 F )
B. ( F / 2 )
c. ( F / 4 )
D. ( F / 8 )
12
1409In induction the charge induced in the near surface of a dielectric is:
A. equal and similar
B. greater and dissimilar
c. lesser and dissimilar
D. equal and dissimilar
12
1410The electrical potential on the surface of a
sphere of radius ( ^{prime} r^{prime} ) due to a charge ( 3 times )
( 10^{-6} ) is ( 500 V ). The intensity of electric field
on the surface of the sphere is ( left[frac{1}{4 pi varepsilon_{0}}=9 times 10^{9} N m^{2} C^{-2}right]left(i n N C^{-1}right) )
A ( .250 / 27 )
B. ( 27 / 250 )
( c .250 )
D. 27
12
1411A dipole of moment ( vec{p} ) is placed in a uniform electric field ( vec{E} ). If the force on the dipole is ( vec{F} ) and the torque is ( vec{tau} ). Then
This question has multiple correct options
( mathbf{A} cdot vec{F}=0 )
B . ( vec{F}=|vec{p}| vec{E} )
( mathbf{c} cdot|vec{tau}|=vec{p} . vec{E} )
D . ( vec{tau}=vec{p} times vec{E} )
12
1412A beam of protons is deflected sideways. could this deflections be caused
a.) By an electric field
b) by a magnetic field
c.) if either could be responsible how would you be able to tell which was
present
12
1413What is NOT an example of an insulator in the kitchen?
A. An oven mitt
B. A wooden spoon
c. Pots and pans
D. A plastic measuring cup
12
1414A copper slab of mass ( 2 g ) contains ( 2 x )
( 10^{22} ) atoms. The charge on the nucleus
of each atom is ( 29 e . ) What fraction of
the electrons must be removed from the
sphere to give it a charge of ( +2 mu C ? )
A ( .58 times 10^{22} )
B. ( 1.25 times 10^{13} )
c. ( 2.16 times 10^{11} )
D. ( 2.16 times 10^{-11} )
12
1415The surface that have zero flux are
( mathbf{A} cdot S_{2}, S_{4}, ) and ( S_{5} )
B. ( S_{1}, S_{3}, S_{4} ) and ( S_{6} )
( c cdot S_{1}, S_{2}, ) and ( S_{3} )
( mathrm{D} cdot S_{2}, S_{3}, ) and ( S_{4} )
12
1416An insulated charged sphere of radius ( 5 c m ) has a potential of ( 10 V ) at the
surface. The potential at the centre will
be :
A. Same as that at ( 5 mathrm{cm} ) from the surface
B. Same as that at ( 25 mathrm{cm} ) from the surface
( c .10 V )
D. Zero
12
1417On the axis and on the equator of an electric dipole for all points
A. On both of them ( V neq 0 )
B. On both of them ( V=0 )
c. on the axis ( V=04 \$ a n d o )nequatorv Vneq o\$s
D. on the axis ( V neq 0 ) and on equator ( V=0 )
12
1418Find out the angle ( theta ) made by string
from vertical in equilibrium position
A ( cdot tan ^{-1}left(frac{m g}{q E}right) )
B. ( sin ^{-1}left(frac{m g}{q E}right) )
c. ( cos ^{-1}left(frac{m g}{q E}right) )
( tan ^{-1}left(frac{q E}{m g}right) )
12
1419For the situation shown in the figure below, match the entries of column with the entries of column II12
1420( 1 mu C ) charge is uniformly distributed on a spherical shell given by equation ( boldsymbol{x}^{2}+boldsymbol{y}^{2}+boldsymbol{z}^{2}=mathbf{2 5} . ) What will be
intensity of electric field at a point
(1,1,2)( ? )
12
1421Differentiate between NPN & PNP
transistors.?
12
1422A ( 100 mathrm{W} ) bulb produces an electric field of ( 2.9 mathrm{V} / mathrm{m} ) at a point ( 3 mathrm{m} ) away. If the bulb is replaced by ( 400 mathrm{W} ) bulb without disturbing other conditions, then the electric field produced at the same point is
A ( .2 .9 mathrm{V} / mathrm{m} )
в. ( 3.5 V / m )
c. ( 4 V / m )
D. ( 5.8 V / m )
12
conducting rod of length I. Another point
particle of the same mass is attached to the other end of the rod. The two
particles carry charges ( +q ) and ( -q ) respectively. This arrangement is held
in a region of a uniform electric field ( mathrm{E} )
such that the rod makes a small angle ( theta )
(say of about 5 degrees) with the field direction. Find an expression for the minimum time needed for the rod to
become parallel to the field after it is set free.
A ( cdot frac{pi}{2}, sqrt{frac{M L}{2 q E}} )
В ( cdot frac{pi}{2}, sqrt{frac{M L}{q E}} )
c. ( pi, sqrt{frac{M L}{q E}} )
D. None of these
12
1424Two small, identical spheres having ( +boldsymbol{Q} )
and ( -Q ) charge are kept at a certain
distance ( F ) force acts between the two
If in the middle of two spheres, another similar sphere having ( +Q ) charge is kept, then it experiences a force in magnitude and direction as
A. Zero having no direction
B. ( 8 F ) towards ( +Q ) charge
c. ( 8 F ) towards ( -Q ) charge
D. ( 4 F ) towards ( +Q ) charge
12
1425A positively charged rod is brought near an uncharged conductor. If the rod is then suddenly withdrawn, the charge left on the conductor will be :
A. positive
B. negative
c. zero
D. data insufficient
12
1426Two mutually perpendicular long straight conductors carrying uniformly distributed charges of linear charge
densitites ( lambda_{1} ) and ( lambda_{2} ) are positioned at a
distance a from each other. How does
the interaction between the rods
depend on a?
12
1427Find the electric field at a distance ” ( z ” )
from the plane. This question has multiple correct options
A ( cdot vec{E}=frac{sigma}{2 epsilon_{0}} hat{k} ) for ( z>0 )
B・ ( vec{E}=-frac{sigma}{2 epsilon_{0}} hat{k} ) for ( z>0 )
c. ( vec{E}=frac{sigma}{2 epsilon_{0}} hat{k} ) for ( z<0 )
D・ ( vec{E}=-frac{sigma}{2 epsilon_{0}} hat{k} ) for ( z<0 )
12
1428Substances which allow heat to pass
through them easily are known as
A. Insulators
B. Conductors
c. semi conductors
D. None
12
1429Two charges of ( +1 mu C &+5 mu C ) are
placed ( 4 c m ) apart, the ratio of the force
exerted by both charges on each other will be –
A . 1: 1
B. 1: 5
c. 5: 1
D. 25: 1
12
1430toppr
below. For which figure the net force on
the charge may be zero
( A )
B.
( c )
( D )
12
1431toppr
4
B
( c )
D. None of these
12
1432Define electric flux. Write its Sl unit.12
1433Which one of the following statements is CORRECT?
A. Lightning rods are made of insulators
B. A conductor holds charge
c. The earth is an insulator
D. An insulator prevents charge from flowing
12
1434Three point charges of ( 2 q,-q ) and ( -q ) are placed at the corner of an equilateral triangle of side a. Then:
This question has multiple correct options
A. the potential at the centroid of the triangle is zero
B. the electric field at the centroid of triangle is zero
c. the dipole moment of the system is ( sqrt{2} q a hat{j} )
D. the dipole moment of the system is ( sqrt{3} q a hat{j} )
12
1435State Gauss’s Law in Electrostatics.12
1436A sphere of radius ( R ) has a volume
density of charge ( rho=k r, ) where ( r ) is the
distance from the centre of the sphere
and ( k ) is constant. The magnitude of the
electric field which exits at the surface
of the sphere is given by:
( left(varepsilon_{0}=text { permittivity of free space }right) )
A ( cdot frac{4 pi k R^{2}}{3 varepsilon_{0}} )
B. ( frac{k R}{3 varepsilon_{0}} )
c. ( frac{4 pi k R}{varepsilon_{0}} )
D. ( frac{k R^{2}}{4 varepsilon_{0}} )
12
1437Graphite is a conductor of electricity because
A . it has free valence electrons
B. it is a non-metal form of Carbon.
c. it is an allotrope of Carbon.
D. Both A and B
12
1438State whether true or false:
Rain water is a non-conductor of
electricity.
A. True
B. False
12
1439The total flux associated with given
cube will be-
where ( ^{prime} boldsymbol{a}^{prime} ) is side of cube ( :left(frac{mathbf{1}}{boldsymbol{epsilon}_{mathbf{0}}}=mathbf{4} boldsymbol{pi} timesright. )
( 9 times 10^{9} ) SI unit)
A ( cdot 162 pi times 10^{-3} N m^{2} / C )
B . ( 162 pi times 10^{3} mathrm{Nm}^{2} / mathrm{C} )
C ( cdot 162 pi times 10^{-6} N m^{2} / C )
D. ( 162 pi times 10^{6} mathrm{Nm}^{2} / mathrm{C} )
12
1440A point charge ( +q ) is placed at the centre of a cube of side ( L ). The electric
flux emerging from the cube is
( ^{mathrm{A}} cdot frac{q}{varepsilon_{0}} )
B. zero
c. ( frac{6 q L^{2}}{varepsilon_{0}} )
D. ( frac{q}{6 L^{2} varepsilon_{0}} )
12
1441If the radius of a sphere doubled
without changing the charge on it, then electric flux originating form the sphere
is:
A . Double
B. Half
c. same
D. zero
12
1442The Sl unit of solid angle is
c. degrees
D. All of the above
12
1443Electric charge is developed due to actual transfer of
A . electron
B. proton
c. neutron
D. none
12
1444What do you molar by electric change?12
1445Electrons are charge carriers in conductors.
A . True
B. False
12
1446A long cylindrical wire carries a linear charge density of ( 3 times 10^{-8} mathrm{Cm}^{-1} . ) An
electron revolve around it in a circular
path under the influence of the
attractive force. ( K E ) of the electron is :
A . ( 1.44 times 10^{-7} J )
В . ( 2.88 times 10^{-17} J )
D. ( 8.64 times 10^{-17} J )
12
1447Given a uniform electric field ( boldsymbol{E}=mathbf{5} times ) ( 10^{3} hat{i} N / C . ) What would be the flux
through the same square if the plane
makes an angle of ( 30^{circ} ) with the ( x ) -axis?
A. ( 5 N m^{2} / C )
B. ( 25 N m^{2} / C )
( mathbf{c} cdot 50 N m^{2} / C )
D. ( 500 mathrm{Nm}^{2} / mathrm{C} )
12
1448Lightning wants to get to ground. It will follow the path(s) of to do so.
A. most impedance
B. least impedance
c. least distance
D. least inductance
12
1449There point charges of
( +2 mu C,-3 mu C,-3 mu C quad ) are kept at
the vertices ( A, B ) and ( C ) respectively of an
equilateral triangle of side ( 20 mathrm{cm} ) as shown in the figure.What should be the
sign and magnitude of the charge to be
placed at the mid – point (M) of side BC
so that the charge at A remains in
equilibrium?
12
1450What is the magnitude of a point charge due to which the electric field
( 30 c m ) away has the magnitude
2 Newton/coulomb? ( [1 / 4 pi varepsilon 0=9 times )
( left.mathbf{1 0}^{mathbf{9}} mathbf{N m}^{mathbf{2}}right] )
A ( cdot 2 times 10^{-1} c ) coulomb
B. ( 3 times 10^{11} ) coulomb
c. ( 5 times 10^{11} ) coulomb
D. ( 9 times 10^{11} ) coulomb
12
1451A solid sphere of radius ( R_{1} ) and volume charge density ( rho=frac{rho_{0}}{r} ) is enclosed by a
hollow sphere of radius ( R_{2} ) with
negative surface charge density ( sigma ), such
that the total charge in the system is
zero, ( rho_{0} ) is positive constant and ( r ) is the
distance from the centre of the sphere. The ratio ( frac{R_{2}}{R_{1}} ) is
A ( cdot frac{sigma}{rho_{0}} )
В. ( sqrt{2 sigma / rho_{0}} )
C ( cdot sqrt{rho_{0} / 2 sigma} )
D. ( frac{rho_{0}}{sigma} )
12
1452Name a metal among the following having highest heat conductivity.
A . Silver
B. Copper
c. Aluminium
D. Brass
12
1453State the kind of charge on a negative ion:
A. positive
B. negative
c. zero
D. cant say
12
1454A charge ( q ) is released in presence of electric (E) and magnetic field (B) then
after some time its velocity is v then:-
( A cdot V propto E )
в. ( v propto frac{1}{E} )
( c cdot V^{2} propto E )
D. ( V propto B^{circ} )
12
1455The electric field intensity at point 0 is
A. zero
В ( cdot frac{q}{4 pi epsilon_{0}}left[frac{1}{r^{2}}-frac{1}{R_{1}^{2}}+frac{1}{R_{2}^{2}}right] )
c. ( frac{q}{4 pi epsilon_{0}}left[frac{1}{r^{2}}-frac{1}{R_{1}^{2}}right] )
D. None of these
12
1456When an ebonite rod is rubbed with fur
the charge acquired by the fur is
A. Positive
B. Negative
c. No charge
D. Can’t say
12
1457Three concentric spherical metallic shells ( A, B ) and ( C ) of ( operatorname{radii} a, b ) and ( c(a< ) ( b<c) ) have charge densities ( sigma,-sigma ) and
( sigma ) respectively. If the shells ( A ) and ( C ) are
at the same potential then the relation between ( a, b ) and ( c ) is :
A ( a+b+c=0 )
0
B . ( a+c=b )
( mathbf{c} cdot a+b=c )
( mathbf{D} cdot a=b+c )
12
1458Mercury is a good conductor of heat.State true or false.
A . True
B. False
12
1459Two large thin metal plates are parallel and close to each other. On their inner
faces, the plates have surface charge
densities of opposite signs and
magnitude ( 27 times 10^{-22} C quad m^{-2} . ) The
electric field ( overrightarrow{boldsymbol{E}} ) in region II in between the plates is
( begin{array}{ll}text { A } cdot 4.25 times 10^{-8} N & C^{-1}end{array} )
в. ( 6.28 times 10^{-10} N quad C^{-1} )
( begin{array}{lll}text { с. } 3.05 times 10^{-10} N & C^{-1}end{array} )
( begin{array}{lll}text { D } cdot & 5.03 times 10^{-10} N & C^{-1}end{array} )
12
1460What happens when a charged balloon is placed near another balloon of the same charge?
A. Attract each other
B. Repel each other
c. Neither attract nor repel
D. All of the above
12
1461Electric flux over a surface in an electric
field may be:
A. positive
B. negative
c. zero
D. positive, negative, zero
12
1462Three charges ( 29,-q .-q ) are located at the vertices of an equilateral triangle. At the triangle
A . field is zero but potential is non-zero
B. field is non- zero and potential are zero.
c. Both field potential are zero
D. Both field potential are non zero
12
1463Sometimes you get a mild spark when you touch the metal surface of a car.
What might be the reason?
A. Due to magnetic attraction, a spark is created
B. Due to electrostatic charge residing on the metal as well as on skin, mild spark is observed
C. Car tries to become neutral by donating electrons
D. Its the only path to ground
12
1464Find the electric field in the region
labelled 2.
( mathbf{A} cdot k_{e} frac{q}{r^{2}} )
( mathbf{B} cdot 2 k_{e} frac{q}{r^{2}} )
( c cdot 3 k_{e} frac{q}{r^{2}} )
D. ( 4 k_{e} frac{q}{r^{2}} )
12
1465Electric field in a region is given by ( overrightarrow{boldsymbol{E}}=-4 boldsymbol{x} hat{boldsymbol{i}}+boldsymbol{6} boldsymbol{y} hat{boldsymbol{j}}, ) find the charge
enclosed in cube of side 1 m oriented as
shown in figure.
( 4 cdot 2 varepsilon )
B.
( c cdot varepsilon )
D. ( 6 varepsilon )
12
1466A dipole is placed in a uniform electric field with its axis parallel to the field. It experiences:
A. both a net force and torque
B. only a net force
c. neither a net force nor a torque
D. only a torque
12
1467Using Gausss law derive an expression
for the electric
field intensity at any point near a uniformly charged thin wire of charge/length as ( 1 mathrm{C} / mathrm{m} )
12
1468Find the net electric flux through the
entire cube
12
1469In a certain region of space, electric field is along the z-direction throughout The magnitude of electric field is, however, not constant but increases
uniformly along the positive z-direction, at the rate of ( 10^{5} N C^{-1} m^{-1} ) per metre. What are the force and torque
experienced by a system having a total
dipole moment equal to ( 10^{-7} mathrm{Cm} ) in the negative z-direction?
12
1470An example in which light emitting diodes are used is :
A. calculator
B. hard drive
c. optical drive
D. analog watch
12
1471A spherically symmetric charge distribution is characterised by a
charge density having the following variation:
( boldsymbol{p}(boldsymbol{r})=boldsymbol{p}_{o}left(mathbf{1}-frac{r}{R}right) ) for ( boldsymbol{r}<boldsymbol{R} )
( boldsymbol{p}(boldsymbol{r})=mathbf{0} ) for ( boldsymbol{r} geqslant boldsymbol{R} )
Where ( r ) is the distance from the centre
of the charge distribution and ( p_{o} ) is a
constant. The electric field at an
internal point
( ^{text {A }} cdot frac{p_{o}}{4 epsilon_{o}}left(frac{r}{3}-frac{r^{2}}{4 R}right) )
в. ( frac{p_{o}}{epsilon_{o}}left(frac{r}{3}-frac{r^{2}}{4 R}right) )
c. ( frac{p_{o}}{3 epsilon_{o}}left(frac{r}{3}-frac{r^{2}}{4 R}right) )
D. ( frac{p_{o}}{12 epsilon_{o}}left(frac{r}{3}-frac{r^{2}}{4 R}right) )
12
1472Figure shows the field produced by two
point charges ( +q ) and ( -q ) of equal
magnitude but opposite signs ( (a n ) electric dipole). Find the electric flux
through each of the closed surfaces ( A )
B, C and D.
12
1473A sphere of radius ( r ) has a volume density of charge ( rho=k r . ) Find the
electric field intensity at the surface of
the sphere.
A. ( frac{4 pi k R^{4}}{3 epsilon_{0}} )
в. ( frac{k R}{3 epsilon_{0}} )
c. ( frac{4 pi k R}{epsilon_{0}} )
D. ( frac{k R^{2}}{4 epsilon_{0}} )
12
1474A electric dipole moment ( overrightarrow{boldsymbol{p}}= ) ( (2.0 hat{i}+3.0 hat{j}) mu C . m ) is placed in a
uniform electric field ( overrightarrow{boldsymbol{E}}= ) ( (3.0 hat{i}+2.0 hat{k}) times 10^{5} N C^{-1} )
This question has multiple correct options
A. The torque that ( vec{E} ) exerts on ( vec{p} ) is ( (0.6 hat{i}-0.4 hat{j}-0.9 hat{k}) N m )
B. The potential energy of the dipole is -0.65
c. The potential energy of the dipole is ( 0.6 J )
D. If the dipole is free to rotate in the electric field, the maximum magnitude of potential energy of the dipole during the rotation is 1.3 .5
12
1475What is an electric dipole?12
1476A charge q is distributed over two spheres of radii ( R ) and ( r ) such that their surface densities are equal. What is the
ratio of the charges on the spheres?
A ( cdot frac{r}{R} )
в. ( frac{r^{2}}{R^{2}} )
c. ( frac{r^{3}}{R^{3}} )
D. ( frac{r^{4}}{R^{4}} )
12
1477Surface density of charge on a sphere of radius ( R ) in terms of electricity intensity ( E ) at a distance ( r ) in free space
is
( left(epsilon_{0}=text { permittivity of free space }right) )
( ^{mathrm{A}} cdot_{epsilon_{0} E}left(frac{R}{r}right)^{2} )
в. ( frac{epsilon_{0} E R}{r^{2}} )
( ^{mathbf{C}} epsilon_{0} Eleft(frac{r}{R}right)^{2} )
D. ( frac{epsilon_{0} E r}{R^{2}} )
12
1478The magnitude of the average electric field normally present in the atmosphere just above the surface of
the Earth is about ( 150 N / C ), directed
inward towards the center of the Earth.
This gives the total net surface charge
carried by the Earth to be : [Given ( epsilon_{0}= ) ( mathbf{8 . 8 5} times mathbf{1 0}^{-12} mathbf{C}^{2} / mathbf{N}-boldsymbol{m}^{2}, boldsymbol{R}_{E}=mathbf{6 . 4} times )
( mathbf{1 0}^{mathbf{6}} boldsymbol{m} )
A ( .+660 k C )
в. ( -660 k C )
( c .-680 k C )
D. ( +680 k C )
12
1479A glass rod is rubbed with silk, is found positively charged. This is because.
A. Electrons are transferred from glass rod to silk.
B. Electrons are transferred from silk to glass rod.
c. Protons are transferred from glass rod to silk.
D. Protons are transferred from silk to glass rod.
12
1480Electric potential at a point ( P, r ) distance away due to a point charge ( q ) at ( A ) is ( V ) volts. If twice of this charge is distributed uniformly on the surface of a hollow sphere of radius ( 4 r ) with center
at point ( A, ) the potential at ( P ) now is :
( A cdot v )
B. V/2
( c cdot v / 4 )
D. v/8
12
1481The electric potential at a point
situated at a distance r on the axis of a
short electric dipole of moment p will be
( mathbf{1} / mathbf{4}left(boldsymbol{pi} varepsilon_{mathbf{0}}right) ) times
( A cdot p / r^{3} )
B. plre
( c cdot p / r )
D. none of the above
12
1482A charge ( (5 sqrt{2}+2 sqrt{5}) ) coulomb is placed on the axis of an infinite disc at a distance a from the centre of disc. The
flux of this charge on the part of the disc having inner and outer radius of a and 2a will be :
A ( cdot frac{3}{2 varepsilon_{0}} )
в. ( frac{1}{2 varepsilon_{0}} )
c. ( frac{2[sqrt{5}+sqrt{2}]}{varepsilon_{0}} )
D. ( frac{2 sqrt{5}+5 sqrt{2}}{2 varepsilon_{0}} )
12
1483In finding the electric field using Gauss law the formula ( |overrightarrow{boldsymbol{E}}|=frac{boldsymbol{q}_{e n c}}{in_{mathbf{0}}|boldsymbol{A}|} ) is
applicable. In the formula ( in_{0} ) is
permittivity of free space, ( boldsymbol{A} ) is the area
of Gaussian surface and ( q_{e n c} ) is charge enclosed by the Gaussian surface. This
equation can be used in which of the
following situation?
A. For any choice of Gaussian surface.
B. Only when the Gaussian surface is an equipotential surface and ( |vec{E}| ) is constant on the surface.
C. Only when ( |vec{E}|= ) constant on the surface
D. Only when the Gaussian surface is an equipotential surface.
12
1484A positively charged particle having some mass is resting in equilibrium at a height H above the center of a fixed, uniformly and positively charged ring of radius R. The force of gravity (mg) acts downwards. The equilibrium of the particle at the given position (H) for small vertical displacement will be:
(Assume ( g ) is uniform)
( ^{mathbf{A}} cdot ) stable if ( H<frac{R}{2} )
B. stable if ( H=frac{R}{sqrt{2}} )
c. unstable if ( H<frac{R}{sqrt{2}} )
D. stable if ( H=frac{R}{2} )
12
1485( A ) and ( B ) are two points on the axis and the perpendicular bisector respectively of an electric dipole. A and B are far away from the dipole and at equal distances from its centre. The fields at ( A ) and ( mathrm{B} ) i.e. ( overrightarrow{boldsymbol{E}_{A}} quad ) and ( overrightarrow{boldsymbol{E}_{B}} ) are respectively
such that
( mathbf{A} cdot overrightarrow{E_{A}}=overrightarrow{E_{B}} )
B . ( overrightarrow{E_{A}}=2 overrightarrow{E_{B}} )
c. ( overrightarrow{E_{A}}=-2 overrightarrow{E_{B}} )
D. ( overrightarrow{E_{A}}=frac{1}{2} overrightarrow{E_{B}} )
12
1486The adjoining figure shows a negatively charged electroscope. If a positively
charged rod touches the knob, the two
leaves will
A. move closer together
B. move farther apart
c. not move at all
D. become positively chargedd
12
1487When we wear nylon dresses during winter then there is
which gets produced due to contact with out body. Fill in the Blank.
A. Magnetic
B. Electrostatic
c. Potential
D. kinetic
12
1488and mass ( 1 k g ) are placed (fixed) symmetrically about a movable central charges of magnitude ( 5 times 10^{-5} C ) and
mass ( 0.5 k g ) as shown. The charge at ( P_{1} ) is removed. The acceleration of the
central charge is
( left[text { Given } boldsymbol{O} boldsymbol{P}_{1}=boldsymbol{O} boldsymbol{P}_{2}=boldsymbol{O} boldsymbol{P}_{3}=boldsymbol{O} boldsymbol{P}_{4}=right. )
( O P_{5}=1 m ; frac{1}{4 pi varepsilon_{0}}=9 times 10^{9} ) in ( S I ) units
( A cdot 9 m s^{-2} ) upwards
B. ( 9 m s^{-2} ) downwards
c. ( 4.5 m s^{-2} ) upwards
D. ( 4.5 m s^{-2} ) downwards
12
1489In the thunderstorm, the charges accumulate near the upper edges of
clouds are
A . negatively charged
B. positively chargedd
c. neutral
D. none of these
12
1490Iron have much lower specific heat
than:
A. steel
B. Copper
c. water
D. none of the above
12
1491An electron falls through a distance of
( 1.5 c m ) in a uniform electric field of
magnitude ( 2 times 10^{4} N / C . ) Now the
direction of the field is reversed keeping the magnitude and unchanged and a proton falls through the same distance. Compute the time of fall in each case,
neglecting gravity.
12
1492The electric field between the inside
and outside layers is:
A ( cdot 10^{6} V m^{-1} )
В. ( 5 times 10^{6} V m^{-1} )
c. ( 0.2 times 10^{7} V m^{-1} )
D. ( 10^{7} V m^{-1} )
12
1493Which of the following statements are
not true?
This question has multiple correct options
A. All charges at rest tend to move higher electric potential to lower electric potential
B. All charges at rest tend to move lower electric potential to higher electric potential
C. Positive charges at rest tend to move form lower electric potential to higher electric potential and negative charges at rest tend to move from higher electric potential to lower electric potential
D. Positive charges at rest tend to move from higher potential to lower potential and negative charges at rest tend to move from lower electric potential to higher potential
12
1494A solid conducting sphere having charge ( 4 mu C ) is placed on nonconducting stand. A point charge ( 2 mu C )
is placed at a distance from the centre
of the sphere, at a double distance of radius of the sphere as shown in the
figure. If conducting sphere is earthed
then charge flow into the ground is :
( A cdot 5 mu C )
B. ( 2 mu C )
( c cdot 10 mu C )
D. ( 1 mu C )
12
1495Five balls numbered 1,2,3,4,5 are
suspended using reparate threads. The balls (1,2),(2,4) and (4,1) show electrostatic attraction, while (2,3) and (4,5) show repulsion. Therefore, ball 1
must be
A. negatively charged
B. positively chargedd
c. neutral
12
1496During a physics lab, a plastic strip was rubbed with cotton and became
positively charged. The correct explanation for why the plastic strip becomes positively charged is that
A. the plastic strip acquired extra protons from the cotton.
B. the plastic strip acquired extra protons during the charging process
c. protons were created as the result of the charging process
D. the plastic strip lost electrons to the cotton during the charging process
12
1497Equipotential surface due to an electric
dipole
A. Does not exist
B. Bisects the line joining two charge of the diople
c. contains the two charge of the dipole
D. Exists in an axial plane
12
1498An electric dipole of momentum ( vec{p} ) is placed in a uniform electric field. The dipole is rotated through a very small angle ( theta ) from equilibrium and is released, find the time period of simple harmonic motion12
1499Figure represents a negatively charged gold leaf electroscope. The distribution of charges on the different parts will be
as:
A. ( A, D ) and ( E ) will have positive charges. ( B ) and ( C ) will have no charge
B. A, D and E will have negative charges. B and C will have no charge
C. ( A, D ) and ( E ) will have negative charges. B and ( C ) will have positive charges.
D. A, D and E will have positive charges. B and C will have negative charges
12
1500A solid insulating sphere of radius a
carries a net positive charge ( 3 Q )
uniformly distributed throughout its volume. Concentric with this sphere is a
conducting spherical shell with inner radius ( n ) and outer radius ( c ) and having
a net charge ( -Q ), as shown
in figure. The electric field in the region
( b>r>a ) is
12
1501If charges ( boldsymbol{q} / 2 ) and ( 2 q ) are placed at the centre of face and at the corner of a
cube, then the total flux through the
cube will be:
A ( cdot frac{q}{2 varepsilon_{0}} )
в. ( frac{q}{varepsilon_{0}} )
c. ( frac{q}{6 varepsilon_{0}} )
D. ( frac{q}{8 varepsilon_{0}} )
12
1502A gold leaf electroscope is given a positive charge so that its leaves diverge. How is the divergence of leaves affected, when an uncharged rod is brought near its disc?
A. divergence increases
B. divergence decreases
c. divergence remains same
D. can’t say
12
1503212
1504If the electric flux entering and leaving
an enclosed surface respectively is ( phi_{1} )
and ( phi_{2}, ) the electric charge inside the surface will be :
( mathbf{A} cdotleft(phi_{2}-phi_{1}right) varepsilon_{0} )
B. ( frac{left(phi_{2}+phi_{1}right)}{varepsilon_{0}} )
c. ( frac{left(phi_{2}-phi_{1}right)}{varepsilon_{0}} )
( mathbf{D} cdotleft(phi_{2}+phi_{1}right) varepsilon_{0} )
12
1505Which wall is at higher potential?
A. Inner
B. Outer
c. Both at same potential
D. None
12
1506In some old texts it is mentioned that
( 4 pi ) lines of force originate from each unit positive charge. Comment on the
statement in view of the fact that ( 4 pi ) is
not an integer.
12
1507Positive electric flux indicates that
electric lines of force are directed
from a point charge.
A. Outwards
B. Onwards
c. Outwards or inwards
D. None of these
12
1508A body has a positive charge of ( 8 x ) ( 10^{-19} mathrm{C} . ) It has :
A. an excess of 5 electrons
B. a deficiency of 5 electrons
c. an excess of 8 electrons
D. a deficiency of 8 electrons
12
1509Electric charges ( boldsymbol{q}, boldsymbol{q} ) and ( -boldsymbol{2} boldsymbol{q} ) are placed at the corners of an equilateral triangle ( A B C ) of side ( L . ) The magnitude of electric dipole moment of the system is
( mathbf{A} cdot q L )
в. ( 2 q L )
c. ( (sqrt{3}) q L )
D. ( 4 q L )
12
1510Two charges ( +20 mu C ) and ( -20 mu C ) are
placed ( 10 m m ) apart. The electric field at
point ( P, ) on the axis of the dipole ( 10 mathrm{cm} ) away from its centre ( boldsymbol{O} ) on the side of
the positive charge is
( mathbf{A} cdot 8.6 times 10^{9} N quad C^{-1} )
B . ( 4.1 times 10^{6} N quad C^{-1} )
C ( .3 .6 times 10^{6} N^{-1} )
D . ( 4.6 times 10^{5} N quad C^{-1} )
12
1511The electric field for ( r<R_{1} ) is given by ( boldsymbol{E}=frac{boldsymbol{X} boldsymbol{Q}}{boldsymbol{pi} varepsilon_{0} boldsymbol{r}^{2}}left[frac{r^{3}-boldsymbol{R}_{1}^{3}}{boldsymbol{R}_{2}^{3}-boldsymbol{R}_{1}^{3}}right] . ) Find ( boldsymbol{X} )12
1512A charge ( Q ) is uniformly distributed over a rod of length ( l ). Consider a hypothetical
cube of edge ( l ) with the centre of the cube at one end of the rod. Find the
minimum possible flux of the electric field through the entire surface of the
cube.
12
1513Charge on an electron is :
( mathbf{A} cdot+e )
в. ( -e )
( c . pm e )
D. All
12
1514The force of interaction (attraction or
repulsion) between two stationary point charges in vacuum is directly proportional to the product of the charges and inversely proportional to the square of distance between them.
This is called
A. Curie’s Law
B. Coulomb’s law
D. Amperr’s Law
12
1515Assertion
Three equal charges are situated on a circle of radius r such that they form on equilateral triangle, then the electric field intensity at the centre is zero
Reason
The force on unit positive charge at the centre, due to the three equal charges are represented by the three sides of a triangle taken in the same order Therefore, electric field intensity at centre is zero
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason is correct
12
1516If the terminal of a gold-leaf electroscope is grounded by touching it with a finger,
A. the gold leaves spread apart in a ‘v”
B. the gold leaves close together.
c. there is no effect on the gold leaves.
D. None of the above
12
1517Consider a spherical Gaussian surface
of radius ( r>c, ) the net charge enclosed
by this surface is ( Y times Q ). Find out the
value of ( boldsymbol{Y} ) ?
12
1518The ratio of the energy required to set up in cube of side ( 10 mathrm{cm} ) uniform magnetic field of ( 4 W b / m^{2} ) and a
uniform electric field of ( 10^{6} V / m ) is:
A ( cdot 1.4 x 10^{7} )
B. ( 1.4 x 10^{5} )
c. ( 1.4 x 10^{6} )
D. ( 1.4 x 10^{3} )
12
1519A ring of diameter dis rotated in a uniform electric field until be position of maximum electric flux is found. The
flux is found to be ( phi ). If the electric field
strength is ( boldsymbol{E}=frac{boldsymbol{X} boldsymbol{phi}}{pi d^{2}} . ) Find out ( boldsymbol{X} ) ?
12
1520Calculate the amount of work done in
turning an electric dipole of dipole
moment ( 3 times 10^{-8} C ) -m from its position
of unstable equilibrium to the position of stable equilibrium in a uniform
electric field of intensity ( 10^{3} N C^{-1} )
12
1521A circular disc of radius 0.2 meter is placed in a uniform magnetic field of ( frac{1}{pi} ) ( boldsymbol{w} boldsymbol{b} / boldsymbol{m}^{2} ) in such way that its axis makes an angle of ( 60^{circ} ) with ( vec{B} ). The magnetic flux linked with the disc is?
A. 0.08 wb
B. 0.01 wb
( c .0 .02 mathrm{wb} )
D. 0.06 wb
12
1522Write down Gauss’s theorem of
electrostatics. Find out intensity of the electric field at a point outside a uniformly charged thin spherical shell with its help.
12
1523A dipole of dipole moment ( P ) is placed at
a distance r form a point change ( Q ) (as
shown in figure).Choose the incorrect
statement.
A. Torque acting on the dipole is zero
B. Force acting on the dipole due to the electrie field produce by ( mathrm{Q} ) is zero
C. potential energy of the dipole due to the point charge ( Q ) is ( frac{Q p}{4 frac{Q_{0}}{r^{2}}} )
D. Force acting on the dipole due to the point charge ( mathrm{Q} ) is ( frac{Q p}{4 pi varepsilon_{0} r^{3}} )
12
1524Potential due to an electric dipole is represented by:
(where ( p ) is the dipole moment, ( r(>> )
2a) is the distance at which the
potential ( V ) of the dipole is calculated
and ( theta ) is the angle between the distance
vector and the dipole.)
A ( cdot V=frac{p cos theta}{4 pi epsilon_{c} r^{4}} )
B. ( V=frac{p sin theta}{4 pi epsilon_{o} r^{2}} )
c. ( V=frac{p sin theta}{4 pi epsilon_{o} r^{4}} )
D. ( V=frac{p cos theta}{4 pi epsilon_{o} r^{2}} )
12
1525An electric dipole made up of a positive and negative charge, each of ( 1 mu C ) separated by a distance of ( 2 mathrm{cm} ), is placed in an electric field of ( 10^{5} N / C ).The work
done in rotating the dipole from the position of stable equilibrium through an angle of ( 180^{0} ) is :
A ( cdot 2 times 10^{-3} ) Joule
B . ( 2 times 10^{-8} ) Joule
c. ( 4 times 10^{-3} ) Joule
D. Zero
12
1526Charge is distributed within a sphere of
radius R with a volume charge density ( rho(r)=frac{A}{r^{2}} e^{-2 r / a}, ) where ( A ) and a are
constants. If ( Q ) is the total charge of this
charge distribution, the radius R is:
A ( cdot frac{a}{2} log left(1-frac{Q}{2 pi a A}right) )
B. ( operatorname{alog}left(1-frac{Q}{2 pi a A}right) )
( ^{mathbf{C}} operatorname{alog}left(frac{1}{1-frac{Q}{2 pi a A}}right) )
( ^{mathrm{D}} cdot_{overline{2}}^{a} log left(frac{1}{1-frac{Q}{2 pi a A}}right) )
12
1527Complete the following sentences:
Like charges ( ldots ldots, ) while unlike charges
each other.
A . attract, attract
B. repel, repel
c. attract, repel
D. repel, attract
12
1528A system has two charges ( boldsymbol{q}_{boldsymbol{A}}=boldsymbol{2 . 5} times )
( mathbf{1 0}^{-7} boldsymbol{C} ) and ( boldsymbol{q}_{B}=-mathbf{2 . 5} times mathbf{1 0}^{-mathbf{7}} boldsymbol{C} ) located
at points ( boldsymbol{A}:(mathbf{0}, mathbf{0}, mathbf{1 5} mathbf{c m}) ) and ( boldsymbol{B} )
( (0,0,+15 c m), ) respectively. What are
the total charge and electric dipole
moment of the system?
12
1529One point electric charge ( Q ) is placed at
the point ( P . A ) closed surface is placed
near the point ( P . ) The electrical flux
passing through a closed surface will be
( mathbf{A} cdot Q epsilon_{0} )
В . ( epsilon_{0} / Q )
( c cdot Q / epsilon_{0} )
D. zero
12
1530A charge ‘ ( q ) ‘ is placed exactly mid way between two charges ‘Q’ and ‘ ( Q ) ‘ separated by a distance ( 2 r ) in air. The
force on the charge ‘ ( q ) ‘ is :
A. ( frac{2 Q}{4 pi epsilon_{0} r^{2}} )
в. ( frac{Q}{4 pi epsilon_{0} r^{2}} )
c. ( Z e r o )
D. ( frac{5 Q}{4 pi epsilon_{0} r^{2}} )
12
1531What is the electric flux through a cube
of side ( 1 mathrm{cm} ) whose encloses an electric
dipole?
12
1532What happens when two inflated
balloons are rubbed with a silk cloth
and brought close to each other?
A. Balloons repel each other
B. Balloons attract each other
C. Balloons neither attract nor repel.
D. Baloons either attract or repel
12
1533Sl unit of permittivity is:
( mathbf{A} cdot F m^{-1} )
В. ( N m^{2} C^{-2} )
c. ( N m^{2} C^{-1} )
D. ( A m^{-1} )
12
1534A charge ‘Q’ is placed at the centre of a hemispherical surface of radius ‘ ( boldsymbol{R} ). The
flux of electric field due to charge ‘ ( Q^{prime} ) through the surface of hemisphere is
( mathbf{A} cdot Q / 4 varepsilon_{0} )
в. ( Q / 4 pi varepsilon_{0} )
c. ( Q / 2 varepsilon_{0} )
D. ( Q / 2 pi varepsilon_{0} )
12
1535Six charges are placed at the corner of a
regular hexagon as shown. If an electron
is placed at the centre ( 0, ) force on it will
be:
A. zero
B. along OF
c. along oc
D. none of these
12
1536Which is a better method to find out if a
body possesses charge?
A. Attraction test
B. Repulsion test
c. Either A or B
D. None of the above
12
1537An electric charge is held at rest in a region of space filled with non-uniform magnetic field. As soon as it is left free.
A. it will move in the direction of the field
B. it will move opposite to the direction of the field
c. it will move perpendicular to the direction of the field
D. it will remain at rest
12
1538The handles of cooking vessels are covered with plastic or wood because:
A. They are beautiful.
B. It is customary
c. They are good conductors of heat
D. They are bad conductors of heat
12
1539State whether the given statement is
True or False :
Positive electrification is due to
deficiency of electrons.
A. True
B. False
12
1540Find the electric field for ( mathbf{0}<boldsymbol{r}<boldsymbol{R} )
( ^{mathbf{A}} cdot_{E}=frac{rho_{0} r^{2}}{3 R epsilon_{0}} )
В. ( quad E=frac{rho_{0} r^{2}}{4 R epsilon_{0}} )
( ^{mathrm{C}} E=frac{rho_{0} r^{2}}{2 R epsilon_{0}} )
D. ( quad E=frac{rho_{0} r^{2}}{R epsilon_{0}} )
12
1541( mathbf{X} ) and ( mathrm{Y} ) are large, parallel conducting plates close to each other. Each face
has an area A. X is given a charge Q.Y is without any charge. Point ( A, B ) and ( C ) are as shown in the figure. Which statement is wrong.
A . The field at B is ( frac{Q}{2 frac{6}{80 A}} )
B. The field at B is ( frac{Q}{6 mathrm{c} A} )
C. The fields at ( A, B ) and ( C ) are of the same magnitude.
D. The fields at A and C are of the same magnitude, but in opposite directions
12
1542The diagram shows four charges
( q_{1}, q_{2}, q_{3}, ) and ( q_{4} ) all lying in the plane of the page. The diagram also shows the dotted circle that represents the crosssection of a spherical Gaussian surface
Point ( P ) is a single point on that surface
Which of the charges contributes to the
electric field at point ( P ? )
( mathbf{A} cdot q_{1} ) and ( q_{3} )
( mathbf{B} cdot q_{2} ) and ( q_{4} )
( mathbf{c} cdot q_{1} ) and ( q_{2} )
( mathbf{D} cdot q_{3} ) and ( q_{4} )
E ( . q_{1}, q_{2}, q_{3}, ) and ( q_{4} )
12
1543Three charges ( mathbf{q}_{1}=mathbf{3} mathbf{m} mathbf{C}, mathbf{q}_{2}=-mathbf{3} mathbf{m} mathbf{C} )
and ( q_{3} ) are kept at the vertices of a
triangle as shown in the figure. If the net
force acting on ( q_{1} ) is ( bar{F} ), the charge ( q_{3} ) would have the magnitude ( left(1+frac{1}{n}right)^{2} m C )
So, ( n ) is:
( mathbf{A} cdot mathbf{8} )
B. 4
( c cdot 1 )
D. 16
12
1544The moment directed along
positive ( x- ) axis of electric field at
point ( (2,2 sqrt{2}, 0) )
A. Along positive ( x- ) axis
B. Along positive ( y- ) axis
c. Along negative ( x- ) axis
D. along negative y-axis
12
1545Two bulbs, one of ( 200 mathrm{W} ) and the other of
( 100 mathrm{W}, ) are connected in series with a
100V battery which has no internal
resistance. Then
A. the current passing through the 200 W bulb is more than that through the 100 w bulb
B. the power dissipation in the 200 W bulb is more than that in the 100 W bulb
c. the voltage drop across the 200 W bulbs is more than that across the ( 100 mathrm{W} ) bulb
D. the power dissipation in the 100 W bulb is more than that in the ( 200 mathrm{w} ) bulb
12
1546A positive point charge is released from
rest at a distance ( r_{0} ) from a positive line charge with uniform density. The speed
(v) of the point charge, as a function of instantaneous distance r from line
charge, is proportional to :-
A ( cdot v propto e^{+r / r_{0}} )
В ( cdot v propto ln left(frac{r}{r_{0}}right) )
c. ( v proptoleft(frac{r}{r_{0}}right) )
D.
12
1547Two point charges ( +8 q ) and ( -2 q ) are located at ( x=0 ) and ( x=L ) respectively. The location of a point on the ( x ) axis at which the net electric field due to these two
point charge is zero is –
A. 2
B. L/4
( c cdot 8 L )
D. 4 L
12
1548The electric field intensity at a point ( boldsymbol{P} )
due to point charge ( q ) kept at point ( Q ) is
( 24 N C^{-1} ) and the electric potential at
point is ( 12 J C^{-1} . ) The order of
magnitude of charge ( q ) is
A ( cdot 10^{-6} C )
B. ( 10^{-7} C )
( mathbf{c} cdot 10^{-10} C )
D. ( 10^{-9} C )
12
1549In the given figure, what is the force on
the charge ( Q ) kept at ( O ) which is at
the mid point of the line ( A B ? )
A ( cdot frac{2 q Q}{pi varepsilon_{0} r^{2}} ) along ( B A )
B. ( frac{2 q Q}{pi varepsilon_{0} r^{2}} ) along ( A B )
c. zero
D. ( frac{q Q}{4 pi varepsilon_{0} r^{2}} )
12
1550Electric intensity due to an electric dipole varies with distance ( r ) as ( E alpha r^{n}, ) where ‘n”
is
A. -3
B. -2
c. -1
D. 0
12
1551Find force on semicircular ring due to
point charge ( boldsymbol{q} )
12
1552The figure shows three infinite nonconducting plates of charge perpendicular to the plane of the paper with charge per unit area ( +sigma,+3 sigma ) and ( -sigma . ) The ratio of the net
electric field at that point ( A ) to that at point ( mathrm{B} ) is ( 1 / x ). Find ( x )
12
1553In uniform electric field, ( boldsymbol{E}=mathbf{1 0} boldsymbol{N} boldsymbol{C}^{-1} )
as shown in figure.
Find. ( (mathrm{i}) boldsymbol{V}_{boldsymbol{A}}-boldsymbol{V}_{boldsymbol{B}} )
(ii) ( V_{B}-V_{C} )
A . -10,20
B. 30,50
( c .-20,30 )
D. 40,50
12
1554Gauss’s law is valid for
A. any closed surface
B. only regular close surface
C . any open surface
D. only irregular open surfaces
12
1555A charge ( Q ) is located at the centre of a
sphere of radius ( R ) Calculate the flux
going out through the surface of the
sphere
( ^{A} cdot frac{Q}{4 pi epsilon_{0} R^{2}} )
в. ( frac{Q}{4 pi epsilon_{0} R} )
c. ( frac{Q}{4 pi R^{2}} )
D. ( underline{Q} )
12
1556Obtain the expression of the electric field due to an infinitely long linear
charged wire along the perpendicu