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The electric force acting between two point charges kept at a certain distance in vacuum is 16N. If the same two charges are kept at the same distance in a medium of dielectric constant 8. The electric force acting between them is _______ N.

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Important Questions on Electrostatics

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Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Three Point charges each equal to

+ q

are placed at the vertices of an equilateral triangle of side

' l'

. The net force on a charge

q_{1}

placed at the centre of the triangle is

HARD

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Two identical non-conducting solid spheres of same mass and charge are suspended in air from a common point by two non-conducting, massless strings of same length. At equilibrium, the angle between the strings is

α

. The spheres are now immersed in a dielectric liquid of density

800 kg m^{- 3}

and dielectric constant

21

. If the angle between the strings remains the same after the immersion, then

EASY

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Two small metal spheres

A

and

B

charged positively are separated by

2 m

in air. The force on a charge of

+ 1 C

placed on the line joining the centres of the spheres and at a distance of

0.5 m

from

A

is found to be zero. The ratio

q_{A} : q_{B}

of charges on

A

and

B

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

A charge

Q

is placed at the centre of the line joining two equal charges

q

. The system of the three charges will be in equilibrium if

Q

is equal to

EASY

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Two charges of equal magnitudes and at a distance $r$ exert a force $F$ on each other. If the charges are halved and distance between them is doubled, then the new force acting on each charge is

EASY

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Two equally charged metal spheres

A

and

B

repel each other with a force of

4 \times 10^{- 5} N

. Another identical uncharged sphere

C

is touched to

A

and then placed at the mid point of the line joining the spheres

A

and

B

. The net electric force on the sphere

C

EASY

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Two electrons are moving with equal speed of

5 \times 10^{5} m s^{- 1}

parallel to each other. The ratio of the electrostatic to the magnetic force between them is

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Point charges $+ q, + q and - q$ are placed at the corners $A, B and C$ respectively of an equilateral triangle $ABC$ . The resultant force on $' - q'$ placed at $C$ acts:

EASY

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Two point charges A and B, having charges

+ Q

and

- Q

respectively, are placed at certain distance apart and force acting between them is

F

. If

25 %

charge of

A

is transferred to

B

, then the force between the charges becomes

HARD

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

A certain charge

2 Q

is divided at first into two parts

q_{1}

and

q_{2}

. Later the charges are placed at a certain distance. If the force of interaction between two charges is maximum then

\frac{Q}{q_{1}} =

HARD

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

A charge $+ q$ is situated at a distance ' $d$ ' away from both the sides of a grounded conducting ' $L$ ' shaped sheet as shown in the figure.

Question Image

The force acting on the charge $+ q$ is

EASY

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

The dimensional formula of coefficient of permittivity for free space (

ε_{0}

) in the equation

F = \frac{1}{4 π ε_{0}} \frac{q_{1} q_{2}}{r^{2}},

where symbols have their usual meanings, is

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Three charges

+ Q, q, + Q

are placed respectively, at distance,

0, 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:

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Three identical charges each of magnitude

3 μ C

are placed at the corners of a right angled triangle

ABC

whose base

B C

and height

B A

are

3 cm

and

4 cm

respectively. Forces on the charge at right angled corner

B

due to charges at

A

and

C

are

F_{1}

and

F_{2}

respectively. The angle between their resultant force and

F_{2}

EASY

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

State Coulomb's law in electrostatics.

HARD

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

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

q_{0} = - \frac{q}{2}

is placed at the origin. If charge

q_{0}

is given a small displacement

(y ≪ a)

along the y-axis, the net force acting on the particle is proportional to :

EASY

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Point charges $1 μC$ and $6 μC$ are placed in air at a certain distance apart. The magnitude of the force on $1 μC$ by $6 μC$ is $F_{1}$ . The magnitude of the force on $6 μC$ by $1 μC$ is $F_{2}$ . Then $F_{1} : F_{2}$ is:

EASY

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Charges $Q_{1}$ and $Q_{2}$ are at points $A$ and $B$ of a right-angled triangle $O A B$ . The resultant electric field at point $O$ is perpendicular to the hypotenuse, then $Q_{1} / Q_{2}$ is proportional to:

Question Image

EASY

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Suppose the charge of a proton and an electron differ slightly. One of them is

e

, the other is

(e + Δ e)

. If the net electrostatic force and gravitational force between two hydrogen atoms placed at a distance

d

(much greater than atomic size) apart is zero, then

Δ e

is of the order of [Given mass of hydrogen

m_{h} = 1.67 \times 10^{- 27} kg

]

HARD

Physics>Electricity and Magnetism>Electrostatics>Coulomb's Law

Two identical charged spheres suspended from a common point by two massless strings of lengths

l

, are initially at a distance

d (d ≪ l)

apart because of their mutual repulsion. The charges begin to leak from both the spheres at a constant rate. As a result, the spheres approach each other with a velocity

υ

. Then

υ

varies as a function of the distance

x

between the spheres, as

The electric force acting between two point charges kept at a certain distance in vacuum is 16N. If the same two charges are kept at the same distance in a medium of dielectric constant 8. The electric force acting between them is _______ N.

Important Questions on Electrostatics

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