A point dipole with dipole moment, p = p 0 K ^ , is kept at the origin. An external electric field given by E = E 0 2 i ^ - 3 j ^ + 4 k ^ , is applied on it. Which one of the following statement is true ?

The force on the dipole is zero while torque rotates the dipole on the x y -plane.

The force on the dipole moves it along the direction of electric field.

The interaction energy between the dipole and electric field is zero.

The potential due to the dipole alone on the x y -plane with z = 0 depends on the value of p 0 .

EASY

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Point charges $q_{1} = - 4 n C$ and $q_{2} = + 4 n C$ are separated by $3 m$ m, forming an electric dipole. The dipole is placed in uniform electric field whose direction makes an angle of $30 º$ with line connecting the charges. What is the magnitude of this field in $N / C$ if the torque exerted on the dipole has magnitude $7.2 \times 10^{- 9} N - m .$

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Important Questions on Electrostatics

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

A short electric dipole has a dipole moment of

16 \times 10^{- 9} C m

. The electric potential due to the dipole at a point at a distance of

0.6 m

from the centre of the dipole, situated on a line making an angle of

60 °

with the dipole axis is:

(\frac{1}{4 π ε_{0}} = 9 \times 10^{9} N m^{2} C^{- 2})

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

Determine the electric dipole moment of the system of three charges, placed on the vertices of an equilateral triangle, as shown in the figure:

Question Image

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

Two identical electric point dipoles have dipole have dipole moments

{\vec{p}}_{1} = p \hat{i}

and

{\vec{p}}_{2} = - p \hat{i}

and are held on the

x

-axis at distance '

a

' from each other. When released, they move along the

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 :

EASY

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

An electric dipole consists of two opposite charges, each of magnitude

1.0 μC

separated by a distance of

2.0 cm .

The dipole is placed in an external field of

10^{5} {NC}^{- 1}

The maximum torque on the dipole is

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

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:

EASY

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

An electric dipole of length

5 cm

is placed in an uniform electric field of

5 \times 10^{5} N C^{- 1}

at an angle of

30 °

with the charges

+ 10 mC

and

- 10 mC

on the dipole. The dipole experiences a torque of

EASY

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

An electric dipole is kept in non-uniform electric field. It generally experiences

EASY

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

In the figure the net torque acting on the dipole is

Question Image

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

Two electric dipoles,

A,

B

with respective dipole moments

\vec{d_{A}} = - 4 q a \hat{i}

and

\vec{d_{B}} = - 2 q a \hat{i}

are placed on the

x

-axis with a separation

R,

as shown in the figure

Question Image

The distance from

A

at which both of them produce the same potential is:

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

A Point dipole

\vec{p} = - p_{0} \hat{x}

is kept at the origin. The potential and electric field due to this dipole on the

y - a x i s

at a distance

d

are, respectively: (Taken

V = 0

at infinity)

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

An electric dipole of dipole moment

\vec{P}

is placed parallel to the uniform electric field of intensity

\vec{E} .

On rotating it through

180 °,

the amount of work done is _______.

EASY

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

An electric dipole is placed at an angle of

30 °

with an electric field intensity

2 \times 10^{5} {N C}^{- 1}

. It experiences a torque equal to

4 N m

. The charge on the dipole, if the dipole length is

2 cm

, is

EASY

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

On the axis and on the equator of an electric dipole for all points ______

EASY

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

A dipole of dipole moment

' P'

and moment of inertia

I

is placed in a uniform electric field

\vec{E}

. If it is displaced slightly from its stable equilibrium position, the period of oscillation of dipole is

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

An electric dipole is formed with two point charges

+ 3.2 \times 10^{- 19} C

and

- 3.2 \times 10^{- 19} C

and separated by a distance of

2.4 \times 10^{- 10} m

. The work done in rotating the dipole through

180 °

from the position of equilibrium in a uniform electric field

4 \times 10^{5} {Vm}^{- 1}

HARD

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

Two ideal electric dipoles $A$ and $B$ , having their dipole moment $p_{1}$ and $p_{2}$ respectively are placed on a plane with their centres at $O$ as shown in the figure. At point $C$ on the axis of dipole $A$ , the resultant electric field is making an angle of $37 °$ with the axis. The ratio of the dipole moment of $A$ and $B, \frac{p_{1}}{p_{2}}$ is $: ($ take $\sin 37 ° = \frac{3}{5})$

Question Image

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

A point dipole with dipole moment,

p = p_{0} \hat{K},

is kept at the origin. An external electric field given by

E = E_{0} (2 \hat{i} - 3 \hat{j} + 4 \hat{k}),

is applied on it. Which one of the following statement is true ?

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

An electric dipole of moment

\vec{p} = (- \hat{i} - 3 \hat{j} + 2 \hat{k}) \times 10^{- 29} C m

at the origin

(0, 0, 0)

. The electric field due to this dipole at

\vec{r} = + \hat{i} + 3 \hat{j} + 5 \hat{k}

(note that

\vec{r} \cdot \vec{p} = 0

) is parallel to:

HARD

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

An electric dipole has fixed dipole moment

\vec{p}

, which makes angle

θ

with respect to

x -

axis. When subjected to an electric field

{\vec{E}}_{1} = E \hat{i},

it experiences a torque

{\vec{T}}_{1} = τ \hat{k}

. When subjected to another electric field

{\vec{E}}_{2} = \sqrt{3} E_{1} \hat{j}

it experiences a torque

{\vec{T}}_{2} = - {\vec{T}}_{1}

. The angle

θ

is:

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Dipole

Charges

- q

and

+ q

, located at

A

and

B

, respectively, constitute an electric dipole. Distance

A B = 2 a

O

is the mid point of the dipole and

O P

is perpendicular to

A B

. A charge

Q

is placed at

P

where

O P = y

and

y ≫ 2 a

. The charge

Q

experiences an electrostatic force

F

. If

Q

is now moved along the equatorial line to

P'

such that

O P' = (\frac{y}{3})

the force on

Q

will be close to

(\frac{y}{3} ≪ 2 a)

Important Questions on Electrostatics

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