A uniformly charged solid sphere of radius R has potential V 0 (measured with respect to ∞ ) on its surface. For this sphere the equipotential surfaces with potential 3 V 0 2 , 5 V 0 4 , 3 V 0 4 and V 0 4 have radius R 1 , R 2 , R 3 and R 4 respectively. Then Note : This question had two option correct at the time of examination. Proper corrections are made in the question to avoid it.

R 1 ≠ 0 and R 2 - R 1 > ( R 4 - R 3 )

Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R. Assertion A : Two metallic spheres are charged to the same potential. One of them is hollow and another is solid, and both have the same radii. Solid sphere will have lower charge than the hollow one. Reason R : Capacitance of metallic spheres depend on the radii of spheres. In the light of the above statements, choose the correct answer from the options given below.

Both A and R are true and R is the correct explanation of A

Both A and R are true but R is not the correct explanation of A

Let σ be the uniform surface charge density of two infinite thin plane sheets shown in figure. Then the electric fields in three different region E I , E I I and E I I I

E → I = - σ ∈ 0 n ^ , E → I I = 0 , E → I I I = σ ∈ 0 n ^

E → I = 2 σ ∈ 0 n ^ , E → I I = 0 , E → I I I = 2 σ ∈ 0 n ^

E → I = 0 , E → I I = σ ∈ 0 n ^ , E → I I I = 0

E → I = σ 2 ∈ 0 n ^ , E → I I = 0 , E → I I I = σ 2 ∈ 0 n ^

Considering a group of positive charges, which of the following statements is correct?

Net potential of the system cannot be zero at a point but net electric field can be zero at that point

Net potential of the system at a point can be zero but net electric field can't be zero at that point

Both the net potential and the net field can be zero at a point

Both the net potential and the net electric field cannot be zero at a point

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JEE Main

IMPORTANT

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A combination of capacitors is set up as shown in the figure. The magnitude of the electric field, due to a point charge Q (having a charge equal to the sum of the charges on the $4 μ F$ and $9 μ F$ capacitors), at a point distant 30 m from it, would equal:

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Important Questions on Electrostatics

HARD

JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 13 - Electrostatics>JEE Main - 10th April 2016>Q 145

Within a spherical charge distribution of charge density

ρ (r),

N equipotential surfaces of potential

V_{0}, V_{0} + ∆ V, V_{0} + 2 ∆ V, \dots V_{0} + N ∆ V (∆ V > 0),

are drawn and have increasing radii

r_{0}, r_{1}, r_{2}, \dots r_{N},

respectively. If the difference in the radii of the surfaces is constant for all values of

V_{0} a n d ∆ V

then :

MEDIUM

JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 13 - Electrostatics>JEE Main - 10th April 2016>Q 146

Figure shows a network of capacitors where the number indicates capacitances in micro Farad. The value of capacitance C if the equivalent capacitance between point A and B is to be $1 μ F$ is :

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 13 - Electrostatics>JEE Main - 10th April 2015>Q 147

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

σ_{1}

is the surface charge on the inner surface and

Q_{1}

net charge on it and

σ_{2}

the surface charge on the outer surface and

Q_{2}

net charge on it then:

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 13 - Electrostatics>JEE Main - 10th April 2015>Q 148

A thin disc of radius $b = 2 a$ 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 a height $h (h < < a)$ from its centre is given as $C h$ then the value of $C$ is

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 13 - Electrostatics>JEE Main - 10th April 2015>Q 149

In the given circuits

(a)

and

(b)

, switches

S_{1}

and

S_{2}

are closed at

t = 0

and kept close for a long time. The variation of currents in the two circuits for

t \geq 0

are shown in the options. (Figures are schematic and not drawn to scale.)
Question Image

MEDIUM

JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 13 - Electrostatics>JEE Main - 10th April 2015>Q 150

If the capacitance of a nanocapacitor is measured in terms of a unit

u

, made by combining the electronic charge

e

, Bohr radius

a_{0}^{},

Planck's constant

h

and speed of light

c

then

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 13 - Electrostatics>JEE Main - 4th April 2015>Q 151

In the given circuit, charge

Q_{2}

on the

2 μ F

capacitor changes as C is varied from

1 μF

3 μ F

Q_{2}

as a function of 'C' is given properly by: (figures are drawn schematically and are not to scale)
Question Image

HARD

JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 13 - Electrostatics>JEE Main - 4th April 2015>Q 152

A uniformly charged solid sphere of radius R has potential $V_{0}$ (measured with respect to $\infty$ ) on its surface. For this sphere the equipotential surfaces with potential $\frac{3 V_{0}}{2}, \frac{5 V_{0}}{4}, \frac{3 V_{0}}{4}$ and $\frac{V_{0}}{4}$ have radius $R_{1}$ , $R_{2}, R_{3}$ and $R_{4}$ respectively. Then

Note : This question had two option correct at the time of examination. Proper corrections are made in the question to avoid it.

A combination of capacitors is set up as shown in the figure. The magnitude of the electric field, due to a point charge Q (having a charge equal to the sum of the charges on the 4 μF and 9 μF capacitors), at a point distant 30 m from it, would equal:

Important Questions on Electrostatics

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A combination of capacitors is set up as shown in the figure. The magnitude of the electric field, due to a point charge Q (having a charge equal to the sum of the charges on the $4 μ F$ and $9 μ F$ capacitors), at a point distant 30 m from it, would equal: