An electric dipole is in unstable equilibrium in the uniform electric field. The angle between its dipole moment and the electric field is

1.  90$°$

2.  120$°$

3.  0$°$

4.  180$°$

An electric dipole of dipole moment p is placed in an electric field of intensity E such that angle between electric field and dipole moment is $\theta$. Assuming that the potential energy of the dipole is zero when $\theta =0°$, the potential energy of the dipole will be

(1) -pE cos$\theta$

(2) pE(1-cos$\theta$)

(3) pE(cos$\theta$-1)

(4) -2pE(cos$\theta$-1)

Eight dipoles of charges of magnitude \((e)\) are placed inside a cube. The total electric flux coming out of the cube will be: 
1. \(\frac{8e}{\epsilon _{0}}\)
2. \(\frac{16e}{\epsilon _{0}}\)
3. \(\frac{e}{\epsilon _{0}}\)
4. zero

An electric dipole is situated in an electric field of uniform intensity E whose dipole moment is p and moment of inertia is I. If the dipole is displaced slightly from the equilibrium position, then the angular frequency of its oscillations is?

1. ${\left(\frac{{\displaystyle pE}}{{\displaystyle I}}\right)}^{1/2}$

2. ${\left(\frac{{\displaystyle pE}}{{\displaystyle I}}\right)}^{3/2}$

3. ${\left(\frac{{\displaystyle I}}{{\displaystyle pE}}\right)}^{1/2}$

4. ${\left(\frac{{\displaystyle p}}{{\displaystyle IE}}\right)}^{1/2}$

Two-point charges +q and –q are held fixed at (–d, 0) and (d, 0) respectively of a (x, y) coordinate system. Then 

(1) E at all points on the y-axis is along $\hat{i}$

(2) The electric field $\overrightarrow{E}$ at all points on the x-axis has the same direction

(3) Dipole moment is 2qd directed along $\hat{i}$

(4) Work has to be done in bringing a test charge from infinity to the origin

Three-point charges + q, -2q and +q are placed at points (x=0, y=a, z=0), (x=0, y=0, z=0) and (x=a, y=0, z=0), respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are:
 

Two short dipoles are placed at a certain distance exert a force 'F' on each other. If the distance between them is doubled then the force will become

1.  F

2.  $\frac{F}{4}$

3.  4F

4.  $\frac{F}{16}$

The net dipole moment of the system is of the magnitude:
         

1.  q $\times$ 2a

2.  2q $\times$ 2a

3.  q $\times$ a

4.  2 $\times$ (2q $\times$ 2a)

A point charge +q is kept at the center of the curvature of thin semicircular wire of length l as shown. The wire has uniformly distributed charge -q on it. The dipole moment of the system is

1.  $\frac{2ql}{{\mathrm{\pi }}^2}$

2.  $\frac{2ql}{\mathrm{\pi }}$

3.  $\frac{\mathrm{\pi }}{2}ql$

4.  Zero

An electric dipole is placed at the centre of a sphere. Which of the following statements is correct?