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Solution
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Q.15 Correct
Q.15 In-correct
Q.15 Unattempt

Match List - I with List - II.

List - I List - II
(A) Electric field inside (distance r > 0 from center) of a uniformly charged spherical shell with surface charge density σ, and radius R. (I) σ/ε0
(B) Electric field at distance r>0 from a uniformly charged infinite plane sheet with surface charge density σ. (II) σ/2ε0
(C) Electric field outside (distance r>0 from center) of a uniformly charged spherical shell with surface charge density σ, and radius R. (III) 0
(D) Electric field between 2 oppositely charged infinite plane parallel sheets with uniform surface charge density σ. (IV) $\frac{\sigma}{\epsilon_0 r^2}$

Choose the correct answer from the options given below :



JEE Main 2025 (Online) 29th January Morning Shift

Match List - I with List - II.

List - I List - II
(A) Electric field inside (distance r > 0 from center) of a uniformly charged spherical shell with surface charge density σ, and radius R. (I) σ/ε0
(B) Electric field at distance r>0 from a uniformly charged infinite plane sheet with surface charge density σ. (II) σ/2ε0
(C) Electric field outside (distance r>0 from center) of a uniformly charged spherical shell with surface charge density σ, and radius R. (III) 0
(D) Electric field between 2 oppositely charged infinite plane parallel sheets with uniform surface charge density σ. (IV) $\frac{\sigma}{\epsilon_0 r^2}$

Choose the correct answer from the options given below :



JEE Main 2025 (Online) 29th January Morning Shift
Q.55 Correct
Q.55 In-correct
Q.55 Unattempt
Two small spheres each of mass 10mg are suspended from a point by threads 0.5m long. They are equally charged and repel each other to a distance of 0.20m. The charge on each of the sphere is
a
21
×108C
. The value of a will be ............. .
[Given, g=10ms2 ]
[25 Feb 2021 Shift 2]
Two small spheres each of mass 10mg are suspended from a point by threads 0.5m long. They are equally charged and repel each other to a distance of 0.20m. The charge on each of the sphere is
a
21
×108C
. The value of a will be ............. .
[Given, g=10ms2 ]
[25 Feb 2021 Shift 2]
Q.56 Correct
Q.56 In-correct
Q.56 Unattempt
Two identical conducting spheres with negligible volume have 2.1nC and 0.1nC charges, respectively. They are brought into contact and then separated by a distance of 0.5m. The electrostatic force acting between the spheres is ____ ×109N.
[Given, 4πε0=
1
9×109
SI unit]
[25 Feb 2021 Shift 2]
Two identical conducting spheres with negligible volume have 2.1nC and 0.1nC charges, respectively. They are brought into contact and then separated by a distance of 0.5m. The electrostatic force acting between the spheres is ____ ×109N.
[Given, 4πε0=
1
9×109
SI unit]
[25 Feb 2021 Shift 2]
Q.57 Correct
Q.57 In-correct
Q.57 Unattempt
Two electrons each are fixed at a distance 2d. A third charge proton placed at the mid-point is displaced slightly by a distance x(x<<d) perpendicular to the line joining the two fixed charges. Proton will execute simple harmonic motion having angular frequency? ( m= mass of charged particle)
[24 Feb 2021 Shift 2]
Two electrons each are fixed at a distance 2d. A third charge proton placed at the mid-point is displaced slightly by a distance x(x<<d) perpendicular to the line joining the two fixed charges. Proton will execute simple harmonic motion having angular frequency? ( m= mass of charged particle)
[24 Feb 2021 Shift 2]
Q.58 Correct
Q.58 In-correct
Q.58 Unattempt
An inclined plane making an angle of 30 with the horizontal is placed in a uniform horizontal electric field 200NC as shown in the figure. A body of mass 1kg and charge 5mC is allowed to slide down from rest at a height of 1m. If the coefficient of friction is 0.2, find the time taken by the body to reach the bottom.
[ Take, g=9.8ms2,sin30=
1
2
,cos30=
3
2
]

[26 Feb 2021 Shift 2]
An inclined plane making an angle of 30 with the horizontal is placed in a uniform horizontal electric field 200NC as shown in the figure. A body of mass 1kg and charge 5mC is allowed to slide down from rest at a height of 1m. If the coefficient of friction is 0.2, find the time taken by the body to reach the bottom.
[ Take, g=9.8ms2,sin30=
1
2
,cos30=
3
2
]

[26 Feb 2021 Shift 2]
Q.59 Correct
Q.59 In-correct
Q.59 Unattempt
Find the electric field at point P (as shown in figure) on the perpendicular bisector of a uniformly charged thin wire of length L carrying a charge Q. The distance of the point P from the centre of the rod is
a=
3
2
L

[26 Feb 2021 Shift 1]
Find the electric field at point P (as shown in figure) on the perpendicular bisector of a uniformly charged thin wire of length L carrying a charge Q. The distance of the point P from the centre of the rod is
a=
3
2
L

[26 Feb 2021 Shift 1]
Q.60 Correct
Q.60 In-correct
Q.60 Unattempt
Given below are two statements:
Statement I An electric dipole is placed at the centre of a hollow sphere. The flux of electric field through the sphere is zero but the electric field is not zero anywhere in the sphere.
Statement II If R is the radius of a solid metallic sphere and Q be the total charge on it. The electric field at any point on the spherical surface of radius r(<R) is zero but the electric flux passing through this closed spherical surface of radius r is not zero.
In the light of the above statements, choose the correct answer from the options given below.
[26 Feb 2021 Shift 2]
Given below are two statements:
Statement I An electric dipole is placed at the centre of a hollow sphere. The flux of electric field through the sphere is zero but the electric field is not zero anywhere in the sphere.
Statement II If R is the radius of a solid metallic sphere and Q be the total charge on it. The electric field at any point on the spherical surface of radius r(<R) is zero but the electric flux passing through this closed spherical surface of radius r is not zero.
In the light of the above statements, choose the correct answer from the options given below.
[26 Feb 2021 Shift 2]
Q.61 Correct
Q.61 In-correct
Q.61 Unattempt
A charge q is placed at one corner of a cube as shown in figure. The flux of electrostatic field E through the shaded area is

[25 Feb 2021 Shift 2]
A charge q is placed at one corner of a cube as shown in figure. The flux of electrostatic field E through the shaded area is

[25 Feb 2021 Shift 2]
Q.62 Correct
Q.62 In-correct
Q.62 Unattempt
The electric field in a region is given E=(
3
5
E0
i
+
4
5
E0
j
)
N
C
. The ratio of flux of reported field through the rectangular surface of area 0.2m2 (parallel to YZ-plane) to that of the surface of area 0.3m2 (parallel to XZ - plane) is a:b, where a=..........
[Here
i
,
j
and
k
are unit vectors along X,Y and Z-axes, respectively]
[25 Feb 2021 Shift 1]
The electric field in a region is given E=(
3
5
E0
i
+
4
5
E0
j
)
N
C
. The ratio of flux of reported field through the rectangular surface of area 0.2m2 (parallel to YZ-plane) to that of the surface of area 0.3m2 (parallel to XZ - plane) is a:b, where a=..........
[Here
i
,
j
and
k
are unit vectors along X,Y and Z-axes, respectively]
[25 Feb 2021 Shift 1]
Q.63 Correct
Q.63 In-correct
Q.63 Unattempt
A point charge of +12µC is at a distance 6cm vertically above the centre of a square of side 12cm as shown in figure. The magnitude of the electric flux through the square will be .......... ×103Nm2C

[24 Feb 2021 Shift 2]
A point charge of +12µC is at a distance 6cm vertically above the centre of a square of side 12cm as shown in figure. The magnitude of the electric flux through the square will be .......... ×103Nm2C

[24 Feb 2021 Shift 2]
Q.64 Correct
Q.64 In-correct
Q.64 Unattempt
A cube of side ' a ' has point charges +Q located at each of its vertices except at the origin where the charge is Q. The electric field at the centre of cube is :

{24Feb2021 Shift1}
A cube of side ' a ' has point charges +Q located at each of its vertices except at the origin where the charge is Q. The electric field at the centre of cube is :

{24Feb2021 Shift1}
Q.65 Correct
Q.65 In-correct
Q.65 Unattempt
An infinite number of point charges, each carrying 1µC charge, are placed along the Y-axis at y=1m,2m,4m,8m. The total force on a 1C point charge, placed at the origin, is x×103N. The value of x to the nearest integer, is .............. .
(Take,
1
4πε0
=9×109Nm2/C2
)
[18 Mar 2021 Shift 2]
An infinite number of point charges, each carrying 1µC charge, are placed along the Y-axis at y=1m,2m,4m,8m. The total force on a 1C point charge, placed at the origin, is x×103N. The value of x to the nearest integer, is .............. .
(Take,
1
4πε0
=9×109Nm2/C2
)
[18 Mar 2021 Shift 2]
Q.66 Correct
Q.66 In-correct
Q.66 Unattempt
Find out the surface charge density at the intersection of point X=3m plane and X-axis, in the region of uniform line charge of 8nCm lying along the Z-axis in free space
[16 Mar 2021 Shift 2]
Find out the surface charge density at the intersection of point X=3m plane and X-axis, in the region of uniform line charge of 8nCm lying along the Z-axis in free space
[16 Mar 2021 Shift 2]
Q.67 Correct
Q.67 In-correct
Q.67 Unattempt
An oil drop of radius 2mm with a density 3gcm3 is held stationary under a constant electric field 3.55×105Vm1 in the Millikan's oil drop experiment. What is the number of excess electrons that the oil drop will possess? (Take, g=9.81ms2 )
[18 Mar 2021 Shift 1]
An oil drop of radius 2mm with a density 3gcm3 is held stationary under a constant electric field 3.55×105Vm1 in the Millikan's oil drop experiment. What is the number of excess electrons that the oil drop will possess? (Take, g=9.81ms2 )
[18 Mar 2021 Shift 1]
Q.68 Correct
Q.68 In-correct
Q.68 Unattempt
The electric field in a region is given by E=
2
5
E0
i
+
3
5
E0
j
with E0=4.0×103NC. The flux of this field through a rectangular surface area 0.4m2 parallel to the yz-plane is .......... Nm2C1.
[17 Mar 2021 Shift 2]
The electric field in a region is given by E=
2
5
E0
i
+
3
5
E0
j
with E0=4.0×103NC. The flux of this field through a rectangular surface area 0.4m2 parallel to the yz-plane is .......... Nm2C1.
[17 Mar 2021 Shift 2]
Q.69 Correct
Q.69 In-correct
Q.69 Unattempt
Two identical tennis balls each having mass 'm' and charge ' q ' are suspended from a fixed point by threads of length l. What is the equilibrium separation when each thread makes a small angle θ with the vertical ?
[27 Jul 2021 Shift 1]
Two identical tennis balls each having mass 'm' and charge ' q ' are suspended from a fixed point by threads of length l. What is the equilibrium separation when each thread makes a small angle θ with the vertical ?
[27 Jul 2021 Shift 1]
Q.70 Correct
Q.70 In-correct
Q.70 Unattempt
A particle of mass 1mg and charge q is lying at the mid-point of two stationary particles kept at a distance '2 m ' when each is carrying same charge 'q'. If the free charged particle is displaced from its equilibrium position through distance ' x (x<<1m). The particle executes SHM. Its angular frequency of oscillation will be _____ ×105rads if q2=10C2
[25 Jul 2021 Shift 1]
A particle of mass 1mg and charge q is lying at the mid-point of two stationary particles kept at a distance '2 m ' when each is carrying same charge 'q'. If the free charged particle is displaced from its equilibrium position through distance ' x (x<<1m). The particle executes SHM. Its angular frequency of oscillation will be _____ ×105rads if q2=10C2
[25 Jul 2021 Shift 1]
Q.71 Correct
Q.71 In-correct
Q.71 Unattempt
An electric dipole is placed on x-axis in proximity to a line charge of linear charge density 3.0×106Cm. Line charge is placed on z-axis and positive and negative charge of dipole is at a distance of 10mm and 12mm from the origin respectively. If total force of 4N is exerted on the dipole, find out the amount of positive or negative charge of the dipole.
[22 Jul 2021 Shift 2]
An electric dipole is placed on x-axis in proximity to a line charge of linear charge density 3.0×106Cm. Line charge is placed on z-axis and positive and negative charge of dipole is at a distance of 10mm and 12mm from the origin respectively. If total force of 4N is exerted on the dipole, find out the amount of positive or negative charge of the dipole.
[22 Jul 2021 Shift 2]
Q.72 Correct
Q.72 In-correct
Q.72 Unattempt
A certain charge Q is divided into two parts q and(Qq). How should the charges Q and q be divided so that q and (Qq) placed at a certain distance apart experience maximum electrostatic repulsion?
[20 Jul 2021 Shift 1]
A certain charge Q is divided into two parts q and(Qq). How should the charges Q and q be divided so that q and (Qq) placed at a certain distance apart experience maximum electrostatic repulsion?
[20 Jul 2021 Shift 1]
Q.73 Correct
Q.73 In-correct
Q.73 Unattempt
What will be the magnitude of electric field at point O as shown in figure? Each side of the figure is l and perpendicular to each other?

[27 Jul 2021 Shift 2]
What will be the magnitude of electric field at point O as shown in figure? Each side of the figure is l and perpendicular to each other?

[27 Jul 2021 Shift 2]
Q.74 Correct
Q.74 In-correct
Q.74 Unattempt
A body having specific charge 8µCg is resting on a frictionless plane at a distance 10cm from the wall (as shown in the figure). It starts moving towards the wall when a uniform electric field of100Vm is applied horizontally towards the wall.

If the collision of the body with the wall is perfectly elastic, then the time period of the motion will be _____ s.

[20 Jul 2021 Shift 1]
A body having specific charge 8µCg is resting on a frictionless plane at a distance 10cm from the wall (as shown in the figure). It starts moving towards the wall when a uniform electric field of100Vm is applied horizontally towards the wall.

If the collision of the body with the wall is perfectly elastic, then the time period of the motion will be _____ s.

[20 Jul 2021 Shift 1]
Q.75 Correct
Q.75 In-correct
Q.75 Unattempt
The total charge enclosed in an incremental volume of 2×109m3 located at the origin isnC, if electric flux density of its field is found as D=exsiny
^
i
excosy
^
j
+2z
^
k
C
m2
.
[22 Jul 2021 Shift 2]
The total charge enclosed in an incremental volume of 2×109m3 located at the origin isnC, if electric flux density of its field is found as D=exsiny
^
i
excosy
^
j
+2z
^
k
C
m2
.
[22 Jul 2021 Shift 2]
Q.76 Correct
Q.76 In-correct
Q.76 Unattempt
Consider a sphere of radius R which carries a uniform charge density ρ. If a sphere of radius
R
2
is carved out of it, as shown, the ratio
|
E
A
|
|
E
B
|
of magnitude of electric field
E
A
and
E
B
, respectively, at points A and B due to the remaining portion is:

[9 Jan. 2020, I]
Consider a sphere of radius R which carries a uniform charge density ρ. If a sphere of radius
R
2
is carved out of it, as shown, the ratio
|
E
A
|
|
E
B
|
of magnitude of electric field
E
A
and
E
B
, respectively, at points A and B due to the remaining portion is:

[9 Jan. 2020, I]
Q.77 Correct
Q.77 In-correct
Q.77 Unattempt
An electric dipole of moment
p
=(
^
i
3
^
j
+2
^
k
)
×1029C.m
is at the origin (0,0,0) . The electric field due to this dipole at
r
=+
^
i
+3
^
j
+5
^
k

(note that
r
.
p
=0
) is parallel to:

[9 Jan. 2020, I]
An electric dipole of moment
p
=(
^
i
3
^
j
+2
^
k
)
×1029C.m
is at the origin (0,0,0) . The electric field due to this dipole at
r
=+
^
i
+3
^
j
+5
^
k

(note that
r
.
p
=0
) is parallel to:

[9 Jan. 2020, I]
Q.78 Correct
Q.78 In-correct
Q.78 Unattempt
A charged particle of mass ' m ' and charge 'q' moving under the influence of uniform electric field E
^
i
and a uniform magnetic field B
k
follows a trajectory from point P to Q as shown in figure. The velocities at P and Q are respectively, v
i
and 2v
j
. Then which of the following statements (A,B,C,D) are the correct? (Trajectory shown is schematic and not to scale)
(A) E=
3
4
(
mv2
qa
)

(B) Rate of work done by the electric field at P is
3
4
(
mv2
a
)

(C) Rate of work done by both the fields at Q is zero
(D) The difference between the magnitude of angular momentum of the particle at P and Q is 2 mav.
[9 Jan. 2020, I]
A charged particle of mass ' m ' and charge 'q' moving under the influence of uniform electric field E
^
i
and a uniform magnetic field B
k
follows a trajectory from point P to Q as shown in figure. The velocities at P and Q are respectively, v
i
and 2v
j
. Then which of the following statements (A,B,C,D) are the correct? (Trajectory shown is schematic and not to scale)
(A) E=
3
4
(
mv2
qa
)

(B) Rate of work done by the electric field at P is
3
4
(
mv2
a
)

(C) Rate of work done by both the fields at Q is zero
(D) The difference between the magnitude of angular momentum of the particle at P and Q is 2 mav.
[9 Jan. 2020, I]
Q.79 Correct
Q.79 In-correct
Q.79 Unattempt
Three charged particles
A,B and C with charges 4q,2q and 2q are present on the circumference of a circle of radius d. The charged particles A,C and centre O of the circle formed an equilateral triangle as shown in figure. Electric field at O along x -direction is:
[8 Jan. 2020, I]
Three charged particles

A,B and C with charges 4q,2q and 2q are present on the circumference of a circle of radius d. The charged particles A,C and centre O of the circle formed an equilateral triangle as shown in figure. Electric field at O along x -direction is:
[8 Jan. 2020, I]
Q.80 Correct
Q.80 In-correct
Q.80 Unattempt
A particle of mass m and charge q is released from rest in a uniform electric field. If there is no other force on the particle, the dependence of its speed v on the distance x travelled by it is correctly given by (graphs are schematic and not drawn to scale)
[8 Jan. 2020, II]
A particle of mass m and charge q is released from rest in a uniform electric field. If there is no other force on the particle, the dependence of its speed v on the distance x travelled by it is correctly given by (graphs are schematic and not drawn to scale)
[8 Jan. 2020, II]
Q.81 Correct
Q.81 In-correct
Q.81 Unattempt
Two infinite planes each with uniform surface charge density +σ are kept in such a way that the angle between them is 30°. The electric field in the region shown between them is given by:

[7 Jan. 2020, I]
Two infinite planes each with uniform surface charge density +σ are kept in such a way that the angle between them is 30°. The electric field in the region shown between them is given by:

[7 Jan. 2020, I]
Q.82 Correct
Q.82 In-correct
Q.82 Unattempt
An electric field
E
=4x
^
i
(y2+1)
^
j
N
C
passes through the box shown in figure. The flux of the electric field through surfaces ABCD and BCGF are marked as ϕ1 and ϕ11 respectively. The difference between (ϕ1ϕ11) is (in Nm2C) _________.

[9 Jan 2020, II]
An electric field
E
=4x
^
i
(y2+1)
^
j
N
C
passes through the box shown in figure. The flux of the electric field through surfaces ABCD and BCGF are marked as ϕ1 and ϕ11 respectively. The difference between (ϕ1ϕ11) is (in Nm2C) _________.

[9 Jan 2020, II]
Q.83 Correct
Q.83 In-correct
Q.83 Unattempt
In finding the electric field using Gauss law the formula|
E
|
=
qenc
0|A|
is applicable. In the formula 0 is permittivity of free space, A is the area of Gaussian surface and qenc is charge enclosed by the Gaussian surface. This equation can be used in which of the following situation?
[8 Jan 2020, I]
In finding the electric field using Gauss law the formula|
E
|
=
qenc
0|A|
is applicable. In the formula 0 is permittivity of free space, A is the area of Gaussian surface and qenc is charge enclosed by the Gaussian surface. This equation can be used in which of the following situation?
[8 Jan 2020, I]
Q.84 Correct
Q.84 In-correct
Q.84 Unattempt
Charges Q1 and Q2 are at points A and B of a right angle triangle OAB (see figure). The resultant electric field at point O is perpendicular to the hypotenuse, then Q1Q2 is proportional to :

[Sep. 06,2020 (I)]
Charges Q1 and Q2 are at points A and B of a right angle triangle OAB (see figure). The resultant electric field at point O is perpendicular to the hypotenuse, then Q1Q2 is proportional to :

[Sep. 06,2020 (I)]
Q.85 Correct
Q.85 In-correct
Q.85 Unattempt
Consider the force F on a charge ‘q’ due to a uniformly charged spherical shell of radius R carrying charge Q distributed uniformly over it. Which one of the following statements is true for F, if ‘q’ is placed at distance r from the centre of the shell?
[Sep. 06, 2020 (II)]
Consider the force F on a charge ‘q’ due to a uniformly charged spherical shell of radius R carrying charge Q distributed uniformly over it. Which one of the following statements is true for F, if ‘q’ is placed at distance r from the centre of the shell?
[Sep. 06, 2020 (II)]
Q.86 Correct
Q.86 In-correct
Q.86 Unattempt
Two charged thin infinite plane sheets of uniform surface charge density σ+ and σ, where |σ+|>|σ|, intersect at right angle. Which of the following best represents the electric field lines for this system?
[Sep. 04, 2020 (I)]
Two charged thin infinite plane sheets of uniform surface charge density σ+ and σ, where |σ+|>|σ|, intersect at right angle. Which of the following best represents the electric field lines for this system?
[Sep. 04, 2020 (I)]
Q.87 Correct
Q.87 In-correct
Q.87 Unattempt
A particle of charge q and mass m is subjected to an electric field E=E0(1ax2) in the x -direction, where a and E0 are constants. Initially the particle was at rest at x=0. Other than the initial position the kinetic energy of the particle becomes zero when the distance of the particle from the origin is :
[Sep. 04,2020 (II)]
A particle of charge q and mass m is subjected to an electric field E=E0(1ax2) in the x -direction, where a and E0 are constants. Initially the particle was at rest at x=0. Other than the initial position the kinetic energy of the particle becomes zero when the distance of the particle from the origin is :
[Sep. 04,2020 (II)]
Q.88 Correct
Q.88 In-correct
Q.88 Unattempt
A charged particle (mass m and charge q ) moves along X axis with velocity V0. When it passes through the origin it enters a region having uniform electric field
E
=E
^
j
which extends upto x=d. Equation of path of electron in the region x>d is :

[Sep. 02, 2020 (I)]
A charged particle (mass m and charge q ) moves along X axis with velocity V0. When it passes through the origin it enters a region having uniform electric field
E
=E
^
j
which extends upto x=d. Equation of path of electron in the region x>d is :

[Sep. 02, 2020 (I)]
Q.89 Correct
Q.89 In-correct
Q.89 Unattempt
A small point mass carrying some positive charge on it, is released from the edge of a table. There is a uniform electric field in this region in the horizontal direction. Which of the following options then correctly describe the trajectory of the mass ? (Curves are drawn schematically and are not to scale).

[Sep. 02, 2020 (I)]
A small point mass carrying some positive charge on it, is released from the edge of a table. There is a uniform electric field in this region in the horizontal direction. Which of the following options then correctly describe the trajectory of the mass ? (Curves are drawn schematically and are not to scale).

[Sep. 02, 2020 (I)]
Q.90 Correct
Q.90 In-correct
Q.90 Unattempt
A particle of mass m and charge q has an initial velocity
v
=v0
j
. If an electric field
E
=E0
i
and magnetic field
B
=B0
i
act on the particle, its speed will double after a time:
[2020, I]
A particle of mass m and charge q has an initial velocity
v
=v0
j
. If an electric field
E
=E0
i
and magnetic field
B
=B0
i
act on the particle, its speed will double after a time:
[2020, I]
Q.91 Correct
Q.91 In-correct
Q.91 Unattempt
Two identical electric point dipoles have dipole moments
P
1
=P
^
i
and
P
2
=P
^
i
and are held on the x axis at distance 'a' from each other. When released, they move along x axis with the direction of their dipole moments remaining unchanged. If the mass of each dipole is ' m ', their speed when they are infinitely far apart is :
[Sep. 06, 2020 (II)]
Two identical electric point dipoles have dipole moments
P
1
=P
^
i
and
P
2
=P
^
i
and are held on the x axis at distance 'a' from each other. When released, they move along x axis with the direction of their dipole moments remaining unchanged. If the mass of each dipole is ' m ', their speed when they are infinitely far apart is :
[Sep. 06, 2020 (II)]
Q.92 Correct
Q.92 In-correct
Q.92 Unattempt
Three charges +Q,q,+Q are placed respectively, at distance,
d
2
and d from the origin, on the x -axis. If the net force experienced by +Q, placed at x=0, is zero, then value of q is:
[9 Jan. 2019 I]
Three charges +Q,q,+Q are placed respectively, at distance,
d
2
and d from the origin, on the x -axis. If the net force experienced by +Q, placed at x=0, is zero, then value of q is:
[9 Jan. 2019 I]
Q.93 Correct
Q.93 In-correct
Q.93 Unattempt
Charge is distributed within a sphere of radius R with a volume charge density p(r)=
A
r2
e2ra
where A and aare constants. If Q is the total charge of this charge distribution, the radius R is:
[9 Jan. 2019, II]
Charge is distributed within a sphere of radius R with a volume charge density p(r)=
A
r2
e2ra
where A and aare constants. If Q is the total charge of this charge distribution, the radius R is:
[9 Jan. 2019, II]
Q.94 Correct
Q.94 In-correct
Q.94 Unattempt
For a uniformly charged ring of radius R, the electric field on its axis has the largest magnitude at a distance h from its centre. Then value of h is:
[9 Jan. 2019 I]
For a uniformly charged ring of radius R, the electric field on its axis has the largest magnitude at a distance h from its centre. Then value of h is:
[9 Jan. 2019 I]
Q.95 Correct
Q.95 In-correct
Q.95 Unattempt
Two point charges q1(10µC) and q2(25µC) are placed on the x -axis at x=1m and x=4m respectively. The electric field (in Vm ) at a point y=3m on y -axis is
[take
1
4π0
=9×109Nm2C2
]
[9 Jan 2019, II]
Two point charges q1(10µC) and q2(25µC) are placed on the x -axis at x=1m and x=4m respectively. The electric field (in Vm ) at a point y=3m on y -axis is
[take
1
4π0
=9×109Nm2C2
]
[9 Jan 2019, II]
Q.96 Correct
Q.96 In-correct
Q.96 Unattempt
An electric field of 1000Vm is applied to an electric dipole at angle of 45°. The value of electric dipole moment is 1029C.m. What is the potential energy of the electric dipole?
[11 Jan 2019, II]
An electric field of 1000Vm is applied to an electric dipole at angle of 45°. The value of electric dipole moment is 1029C.m. What is the potential energy of the electric dipole?
[11 Jan 2019, II]
Q.97 Correct
Q.97 In-correct
Q.97 Unattempt
Charges q and +q located at A and B, respectively constitute an electric dipole. Distance AB=2a,O is the mid point of the dipole and OP is perpendicular to AB. A charge Q is placed at P where OP=y and y>>2a. The charge Q experiences an electrostatic force F. If Q is now moved along the equatorial line to P such that OP =(
y
3
)
,
the force on Q will be close to: (
y
3
>
>2a
)

[10 Jan 2019, II]
Charges q and +q located at A and B, respectively constitute an electric dipole. Distance AB=2a,O is the mid point of the dipole and OP is perpendicular to AB. A charge Q is placed at P where OP=y and y>>2a. The charge Q experiences an electrostatic force F. If Q is now moved along the equatorial line to P such that OP =(
y
3
)
,
the force on Q will be close to: (
y
3
>
>2a
)

[10 Jan 2019, II]
Q.98 Correct
Q.98 In-correct
Q.98 Unattempt
A simple pendulum of length L is placed between the plates of a parallel plate capacitor having electric field E as shown in figure. Its bob has mass m and charge q. The time period of the pendulum is given by:

[10 April 2019, II]
A simple pendulum of length L is placed between the plates of a parallel plate capacitor having electric field E as shown in figure. Its bob has mass m and charge q. The time period of the pendulum is given by:

[10 April 2019, II]
Q.99 Correct
Q.99 In-correct
Q.99 Unattempt
Four point charges q,+q,+q and q are placed on y -axis at y=2d,y=d,y=+d and y=+2d, respectively. The magnitude of the electric field E at a point on the x -axis at x=D, with D>>d, will behave as:
[9 April 2019, II]
Four point charges q,+q,+q and q are placed on y -axis at y=2d,y=d,y=+d and y=+2d, respectively. The magnitude of the electric field E at a point on the x -axis at x=D, with D>>d, will behave as:
[9 April 2019, II]
Q.100 Correct
Q.100 In-correct
Q.100 Unattempt
The bob of a simple pendulum has mass 2g and a charge of 5.0
1
4
C
. It is at rest in a uniform horizontal electric field of intensity 2000Vm. At equilibrium, the angle that the pendulum makes with the vertical is :
( take g=10ms2)
[8 April 2019 I]
The bob of a simple pendulum has mass 2g and a charge of 5.0
1
4
C
. It is at rest in a uniform horizontal electric field of intensity 2000Vm. At equilibrium, the angle that the pendulum makes with the vertical is :
( take g=10ms2)
[8 April 2019 I]
Q.101 Correct
Q.101 In-correct
Q.101 Unattempt
Shown in the figure is a shell made of a conductor. It has inner radius a and outer radius b, and carries charge Q. At its centre is a dipole
p
as shown. In this case :

[12 April 2019, I]
Shown in the figure is a shell made of a conductor. It has inner radius a and outer radius b, and carries charge Q. At its centre is a dipole
p
as shown. In this case :

[12 April 2019, I]
Q.102 Correct
Q.102 In-correct
Q.102 Unattempt
Let a total charge 2Q be distributed in a sphere of radius R, with the charge density given by ρ(r)=kr, 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, from the centre. If A and B do not experience any force, then.
[12 April 2019, II]
Let a total charge 2Q be distributed in a sphere of radius R, with the charge density given by ρ(r)=kr, 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, from the centre. If A and B do not experience any force, then.
[12 April 2019, II]
Q.103 Correct
Q.103 In-correct
Q.103 Unattempt
An electric dipole is formed by two equal and opposite charges q with separation d. The charges have same mass m. It is kept in a uniform electric field E. If it is slightly rotated from its equilibrium orientation, then its angular frequency ω is :
[8 April 2019, II]
An electric dipole is formed by two equal and opposite charges q with separation d. The charges have same mass m. It is kept in a uniform electric field E. If it is slightly rotated from its equilibrium orientation, then its angular frequency ω is :
[8 April 2019, II]
Q.104 Correct
Q.104 In-correct
Q.104 Unattempt
Two identical conducting spheres A and B, carry equal charge. They are separated by a distance much larger than their diameter, and the force between them is F. A third identical conducting sphere, C, is uncharged. Sphere C is first touched to A, then to B, and then removed. As a result, the force between A and B would be equal to
[Online April 16,2018]
Two identical conducting spheres A and B, carry equal charge. They are separated by a distance much larger than their diameter, and the force between them is F. A third identical conducting sphere, C, is uncharged. Sphere C is first touched to A, then to B, and then removed. As a result, the force between A and B would be equal to
[Online April 16,2018]
Q.105 Correct
Q.105 In-correct
Q.105 Unattempt
A body of mass M and charge q is connected to a spring of spring constant k. It is oscillating along x - direction about its equilibrium position, taken to be at x=0, with an amplitude A. An electric field E is applied along the X-direction. Which of the following statements is correct?
[Online April 15, 2018]
A body of mass M and charge q is connected to a spring of spring constant k. It is oscillating along x - direction about its equilibrium position, taken to be at x=0, with an amplitude A. An electric field E is applied along the X-direction. Which of the following statements is correct?
[Online April 15, 2018]
Q.106 Correct
Q.106 In-correct
Q.106 Unattempt
A solid ball of radius R has a charge density ρ given byρ=ρ0(1
r
R
)
for 0rR. The electric field outside the ball is:
[Online April 15, 2018]
A solid ball of radius R has a charge density ρ given byρ=ρ0(1
r
R
)
for 0rR. The electric field outside the ball is:
[Online April 15, 2018]
Q.107 Correct
Q.107 In-correct
Q.107 Unattempt
A charge Q is placed at a distance a2 above the centre of the square surface of edge a as shown in the figure. The electric flux through the square surface is:

[Online April 15, 2018]
A charge Q is placed at a distance a2 above the centre of the square surface of edge a as shown in the figure. The electric flux through the square surface is:

[Online April 15, 2018]
Q.108 Correct
Q.108 In-correct
Q.108 Unattempt
An electric dipole has a fixed dipole moment
p
,
which makes angle θ with respect to x-axis. When subjected to an electric field
E
1
=E
^
i
,
it experiences a torque
T
1
=τ
^
i
When subjected to another electric field
E
2
=3E1
^
j
it experiences torque
T
2
=
T
1
.
The angle θ is:
[2017]
An electric dipole has a fixed dipole moment
p
,
which makes angle θ with respect to x-axis. When subjected to an electric field
E
1
=E
^
i
,
it experiences a torque
T
1
=τ
^
i
When subjected to another electric field
E
2
=3E1
^
j
it experiences torque
T
2
=
T
1
.
The angle θ is:
[2017]
Q.109 Correct
Q.109 In-correct
Q.109 Unattempt
Four closed surfaces and corresponding charge distributions are shown below.
Let the respective electric fluxes through the surfaces be Φ1,Φ2,Φ3, and Φ4. Then :
[Online April 9, 2017]
Four closed surfaces and corresponding charge distributions are shown below.

Let the respective electric fluxes through the surfaces be Φ1,Φ2,Φ3, and Φ4. Then :
[Online April 9, 2017]
Q.110 Correct
Q.110 In-correct
Q.110 Unattempt
The region between two concentric spheres of radii 'a' and 'b', respectively (see figure), have volume charge density ρ=
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:

[2016]
The region between two concentric spheres of radii 'a' and 'b', respectively (see figure), have volume charge density ρ=
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:

[2016]
Q.111 Correct
Q.111 In-correct
Q.111 Unattempt
Shown in the figure are two point charges +Q and Q inside the cavity of a spherical shell. The charges are kept near the surface of the cavity on opposite sides of the centre of the shell. If sigma1 is the surface charge on the inner surface and Q1 net charge on it and σ2 the surface charge on the outer surface and Q2 net charge on it then :
[Online April 10, 2015]
Shown in the figure are two point charges +Q and Q inside the cavity of a spherical shell. The charges are kept near the surface of the cavity on opposite sides of the centre of the shell. If sigma1 is the surface charge on the inner surface and Q1 net charge on it and σ2 the surface charge on the outer surface and Q2 net charge on it then :
[Online April 10, 2015]
Q.112 Correct
Q.112 In-correct
Q.112 Unattempt
A long cylindrical shell carries positive surface charge σ in the upper half and negative surface charge σ in the lower half. The electric field lines around the cylinder will look like figure given in : (figures are schematic and not drawn to scale)
[2015]
A long cylindrical shell carries positive surface charge σ in the upper half and negative surface charge σ in the lower half. The electric field lines around the cylinder will look like figure given in : (figures are schematic and not drawn to scale)
[2015]
Q.113 Correct
Q.113 In-correct
Q.113 Unattempt
A wire of length L(=20cm), is bent into a semicircular arc. If the two equal halves of the arc were each to be uniformly charged with charges ±Q,[|Q|=103ε0. Coulomb where ε0 is the permittivity (in SI units) of free space] the net electric field at the centre O of the semicircular arc would be :

[Online April 11, 2015]
A wire of length L(=20cm), is bent into a semicircular arc. If the two equal halves of the arc were each to be uniformly charged with charges ±Q,[|Q|=103ε0. Coulomb where ε0 is the permittivity (in SI units) of free space] the net electric field at the centre O of the semicircular arc would be :

[Online April 11, 2015]
Q.114 Correct
Q.114 In-correct
Q.114 Unattempt
A thin disc of radius b=2a has a concentric hole of radius ' a ' in it (see figure). It carries uniform surface charge ' σ ' on it. If the electric field on its axis at height ' h ' (h<<a) from its centre is given as ' Ch ' then value of ' C ' is :

[Online April 10, 2015]
A thin disc of radius b=2a has a concentric hole of radius ' a ' in it (see figure). It carries uniform surface charge ' σ ' on it. If the electric field on its axis at height ' h ' (h<<a) from its centre is given as ' Ch ' then value of ' C ' is :

[Online April 10, 2015]
Q.115 Correct
Q.115 In-correct
Q.115 Unattempt
The electric field in a region of space is given by,
E
=Eo
^
i
+2Eo
^
j
where Eo=100NC. The flux of the field through a circular surface of radius 0.02 m parallel to the YZ plane is nearly:
[Online April 19, 2014]
The electric field in a region of space is given by,
E
=Eo
^
i
+2Eo
^
j
where Eo=100NC. The flux of the field through a circular surface of radius 0.02 m parallel to the YZ plane is nearly:
[Online April 19, 2014]
Q.116 Correct
Q.116 In-correct
Q.116 Unattempt
A spherically symmetric charge distribution is characterised by a charge density having the following variations:
ρ(r)=ρo(1
r
R
)
for r<R
ρ(r)=0 for rR
Where r is the distance from the centre of the charge distribution ρ0 is a constant. The electric field at an internal point (r<R) is:
[Online April 12,2014]
A spherically symmetric charge distribution is characterised by a charge density having the following variations:
ρ(r)=ρo(1
r
R
)
for r<R
ρ(r)=0 for rR
Where r is the distance from the centre of the charge distribution ρ0 is a constant. The electric field at an internal point (r<R) is:
[Online April 12,2014]
Q.117 Correct
Q.117 In-correct
Q.117 Unattempt
The magnitude of the average electric field normally present in the atmosphere just above the surface of the Earth is about 150NC , directed inward towards the center of the Earth. This gives the total net surface charge carried by the Earth to be:
[Given ε0=8.85×1012C2Nm2, RE=6.37×106m]
[Online April 9, 2014]
The magnitude of the average electric field normally present in the atmosphere just above the surface of the Earth is about 150NC , directed inward towards the center of the Earth. This gives the total net surface charge carried by the Earth to be:
[Given ε0=8.85×1012C2Nm2, RE=6.37×106m]
[Online April 9, 2014]
Q.118 Correct
Q.118 In-correct
Q.118 Unattempt
Two charges, each equal to q, are kept at x=a and x=a on the x -axis. A particle of mass m and charge q0=
q
2
is placed at the origin. If charge q0 is given a small displacement (y<<a) along the y-axis, the net force acting on the particle is proportional to
[2013]
Two charges, each equal to q, are kept at x=a and x=a on the x -axis. A particle of mass m and charge q0=
q
2
is placed at the origin. If charge q0 is given a small displacement (y<<a) along the y-axis, the net force acting on the particle is proportional to
[2013]
Q.119 Correct
Q.119 In-correct
Q.119 Unattempt
Two balls of same mass and carrying equal charge are hung from a fixed support of length l. At electrostatic equilibrium, assuming that angles made by each thread is small, the separation, x between the balls is proportional to:
[Online April 9, 2013]
Two balls of same mass and carrying equal charge are hung from a fixed support of length l. At electrostatic equilibrium, assuming that angles made by each thread is small, the separation, x between the balls is proportional to:
[Online April 9, 2013]
Q.120 Correct
Q.120 In-correct
Q.120 Unattempt
The surface charge density of a thin charged disc of radius R is σ. The value of the electric field at the centre of the disc is
σ
20
.
With respect to the field at the centre, the electric field along the axis at a distance R from the centre of the disc :
[Online April 25, 2013]
The surface charge density of a thin charged disc of radius R is σ. The value of the electric field at the centre of the disc is
σ
20
.
With respect to the field at the centre, the electric field along the axis at a distance R from the centre of the disc :
[Online April 25, 2013]
Q.121 Correct
Q.121 In-correct
Q.121 Unattempt
A liquid drop having 6 excess electrons is kept stationary under a uniform electric field of 25.5kVm1. The density of liquid is 1.26×103kg m3. The radius of the drop is (neglect buoyancy).
[Online April 23, 2013]
A liquid drop having 6 excess electrons is kept stationary under a uniform electric field of 25.5kVm1. The density of liquid is 1.26×103kg m3. The radius of the drop is (neglect buoyancy).
[Online April 23, 2013]
Q.122 Correct
Q.122 In-correct
Q.122 Unattempt
Two point dipoles of dipole moment
p
1
and
p
2
are at a distance x from each other and
p
1
p
2
.
The force between the dipoles is:
[Online April 9, 2013]
Two point dipoles of dipole moment
p
1
and
p
2
are at a distance x from each other and
p
1
p
2
.
The force between the dipoles is:
[Online April 9, 2013]
Q.123 Correct
Q.123 In-correct
Q.123 Unattempt
In a uniformly charged sphere of total charge Q and radius R, the electric field E is plotted as function of distance from the centre, The graph which would correspond to the above will be:
[2012]
In a uniformly charged sphere of total charge Q and radius R, the electric field E is plotted as function of distance from the centre, The graph which would correspond to the above will be:
[2012]
Q.124 Correct
Q.124 In-correct
Q.124 Unattempt
Three positive charges of equal value q are placed at vertices of an equilateral triangle. The resulting lines of force should be sketched as in
[Online May 26, 2012]
Three positive charges of equal value q are placed at vertices of an equilateral triangle. The resulting lines of force should be sketched as in
[Online May 26, 2012]
Q.125 Correct
Q.125 In-correct
Q.125 Unattempt
The flat base of a hemisphere of radius a with no charge inside it lies in a horizontal plane. A uniform electric field
E
is applied at an angle
π
4
with the vertical direction. The electric flux through the curved surface of the hemisphere is

[Online May 19, 2012]
The flat base of a hemisphere of radius a with no charge inside it lies in a horizontal plane. A uniform electric field
E
is applied at an angle
π
4
with the vertical direction. The electric flux through the curved surface of the hemisphere is

[Online May 19, 2012]
Q.126 Correct
Q.126 In-correct
Q.126 Unattempt
Two identical charged spheres suspended from a common point by two massless strings of length l are initially a distance d(d<<l) apart because of their mutual repulsion. The charge begins to leak from both the spheres at a constant rate. As a result charges approach each other with a velocity v. Then as a function of distance x between them,
[2011]
Two identical charged spheres suspended from a common point by two massless strings of length l are initially a distance d(d<<l) apart because of their mutual repulsion. The charge begins to leak from both the spheres at a constant rate. As a result charges approach each other with a velocity v. Then as a function of distance x between them,
[2011]
Q.127 Correct
Q.127 In-correct
Q.127 Unattempt
A thin semi-circular ring of radius r has a positive charge q distributed uniformly over it. The net field
E
at the centre O is

[2010]
A thin semi-circular ring of radius r has a positive charge q distributed uniformly over it. The net field
E
at the centre O is

[2010]
Q.128 Correct
Q.128 In-correct
Q.128 Unattempt
Let there be a spherically symmetric charge distribution with charge density varying as ρ(r)=ρ0(
5
4
r
R
)
upto r =R, and ρ(r)=0 for r>R, where r is the distance from the origin. The electric field at a distance r(r<R) from the origin is given by
[2010]
Let there be a spherically symmetric charge distribution with charge density varying as ρ(r)=ρ0(
5
4
r
R
)
upto r =R, and ρ(r)=0 for r>R, where r is the distance from the origin. The electric field at a distance r(r<R) from the origin is given by
[2010]
Q.129 Correct
Q.129 In-correct
Q.129 Unattempt
A charge Q is placed at each of the opposite corners of a square. A charge q is placed at each of the other two corners. If the net electrical force on Q is zero, then Qq equals:
[2009]
A charge Q is placed at each of the opposite corners of a square. A charge q is placed at each of the other two corners. If the net electrical force on Q is zero, then Qq equals:
[2009]
Q.130 Correct
Q.130 In-correct
Q.130 Unattempt
This question contains Statement- 1 and Statement- 2 . Of the four choices given after the statements, choose the one that best describes the two statements.
Statement-1: For a charged particle moving from point P to point Q, the net work done by an electrostatic field on the particle is independent of the path connecting point P to point Q.
Statement- 2 : The net work done by a conservative force on an object moving along a closed loop is zero.
[2009]
This question contains Statement- 1 and Statement- 2 . Of the four choices given after the statements, choose the one that best describes the two statements.
Statement-1: For a charged particle moving from point P to point Q, the net work done by an electrostatic field on the particle is independent of the path connecting point P to point Q.
Statement- 2 : The net work done by a conservative force on an object moving along a closed loop is zero.
[2009]
Q.131 Correct
Q.131 In-correct
Q.131 Unattempt
Let ρ(r)=
Q
πR4
r
be the charge density distribution for a solid sphere of radius R and total charge Q. For a point P ' inside the sphere at distance r1 from the centre of the sphere, the magnitude of electric field is :
[2009]
Let ρ(r)=
Q
πR4
r
be the charge density distribution for a solid sphere of radius R and total charge Q. For a point P ' inside the sphere at distance r1 from the centre of the sphere, the magnitude of electric field is :
[2009]
Q.132 Correct
Q.132 In-correct
Q.132 Unattempt
A thin spherical shell of radus R has charge Q spread uniformly over its surface. Which of the following graphs most closely represents the electric field E(r) produced by the shell in the range 0 r<, where r is the distance from the centre of the shell?
[2008]
A thin spherical shell of radus R has charge Q spread uniformly over its surface. Which of the following graphs most closely represents the electric field E(r) produced by the shell in the range 0 r<, where r is the distance from the centre of the shell?
[2008]
Q.133 Correct
Q.133 In-correct
Q.133 Unattempt
If gE and gM 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
[2007]
If gE and gM 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
[2007]
Q.134 Correct
Q.134 In-correct
Q.134 Unattempt
Two spherical conductors A and B of radii 1mm and 2mm are separated by a distance of 5cm and are uniformly charged. If the spheres are connected by a conducting wire then in equilibrium condition, the ratio of the magnitude of the electric fields at the surfaces of spheres A and B is
[2006]
Two spherical conductors A and B of radii 1mm and 2mm are separated by a distance of 5cm and are uniformly charged. If the spheres are connected by a conducting wire then in equilibrium condition, the ratio of the magnitude of the electric fields at the surfaces of spheres A and B is
[2006]
Q.135 Correct
Q.135 In-correct
Q.135 Unattempt
An electric dipole is placed at an angle of 30° to a nonuniform electric field. The dipole will experience
[2006]
An electric dipole is placed at an angle of 30° to a nonuniform electric field. The dipole will experience
[2006]
Q.136 Correct
Q.136 In-correct
Q.136 Unattempt
Two point charges +8q and 2q 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 charges is zero is
[2005]
Two point charges +8q and 2q 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 charges is zero is
[2005]
Q.137 Correct
Q.137 In-correct
Q.137 Unattempt
A charged ball B hangs from a silk thread S, which makes an angle θ with a large charged conducting sheet P, as shown in the figure. The surface charge density σ of the sheet is proportional to

[2005]
A charged ball B hangs from a silk thread S, which makes an angle θ with a large charged conducting sheet P, as shown in the figure. The surface charge density σ of the sheet is proportional to

[2005]
Q.138 Correct
Q.138 In-correct
Q.138 Unattempt
Two spherical conductors B and C having equal radii and carrying equal charges on them repel each other with a force F when kept apart at some distance. A third spherical conductor having same radius as that B but uncharged is brought in contact with B, then brought in contact with C and finally removed away from both. The new force of repulsion between B and C is
[2004]
Two spherical conductors B and C having equal radii and carrying equal charges on them repel each other with a force F when kept apart at some distance. A third spherical conductor having same radius as that B but uncharged is brought in contact with B, then brought in contact with C and finally removed away from both. The new force of repulsion between B and C is
[2004]
Q.139 Correct
Q.139 In-correct
Q.139 Unattempt
Four charges equal to Q are placed at the four corners of a square and a charge q is at its centre. If the system is in equilibrium the value of q is
[2004]
Four charges equal to Q are placed at the four corners of a square and a charge q is at its centre. If the system is in equilibrium the value of q is
[2004]
Q.140 Correct
Q.140 In-correct
Q.140 Unattempt
A charged oil drop is suspended in a uniform field of 3×104 vm so that it neither falls nor rises. The charge on the drop will be (Take the mass of the charge =9.9×1015kg and g=10ms2)
[2004]
A charged oil drop is suspended in a uniform field of 3×104 vm so that it neither falls nor rises. The charge on the drop will be (Take the mass of the charge =9.9×1015kg and g=10ms2)
[2004]
Q.141 Correct
Q.141 In-correct
Q.141 Unattempt
Three charges q1,+q2 and q3 are place as shown in the figure. The x - component of the force on q1 is proportional to

[2003]
Three charges q1,+q2 and q3 are place as shown in the figure. The x - component of the force on q1 is proportional to

[2003]
Q.142 Correct
Q.142 In-correct
Q.142 Unattempt
If the electric flux entering and leaving an enclosed surface respectively is ϕ1 and ϕ2, the electric charge inside the surface will be
[2003]
If the electric flux entering and leaving an enclosed surface respectively is ϕ1 and ϕ2, the electric charge inside the surface will be
[2003]
Q.143 Correct
Q.143 In-correct
Q.143 Unattempt
If 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
[2002]
If 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
[2002]
Q.144 Correct
Q.144 In-correct
Q.144 Unattempt
A charged particle q is placed at the centre O of cube of length L(ABCDEFGH). Another same charge q is placed at a distance L from O. Then the electric flux through ABCD is

[2002]
A charged particle q is placed at the centre O of cube of length L(ABCDEFGH). Another same charge q is placed at a distance L from O. Then the electric flux through ABCD is

[2002]
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