$A$ wheel of mass $m$ has charges $+q$ and $-q$ at diametrically opposite points. It remains in equilibrium on a rough inclined plane of inclination $\theta$ in the presence of a uniform horizontal electric field $E$. Find the value of $E$.

An electric dipole of moment $p$ is placed at the origin along the $x$-axis. The electric field at a point $P$,whose position vector makes an angle $\theta$ with the $x$-axis,will make an angle $\phi$ with the $x$-axis. If $\tan \alpha = \frac{1}{2} \tan \theta$,where $\alpha$ is the angle between the electric field vector and the position vector,then the angle $\phi$ that the electric field makes with the $x$-axis is:

Select the $WRONG$ statement about polar molecules.

$A$ given charge situated at a distance $r$ from an electric dipole on its axis experiences a force $F$. If the distance of the charge from the dipole is doubled,the force acting on the charge will be

An electric dipole of dipole moment $P$ is placed parallel to a uniform electric field of intensity $E$. On rotating it through an angle of $90^\circ$ from this position, the amount of work done is . . . . . . .

Two electric dipoles of moment $P$ and $8P$ are placed in opposite directions on a line at a distance of $24 \text{ cm}$. The electric field will be zero at a point between the dipoles whose distance from the dipole of moment $P$ is $x_1$. When $8P$ is replaced by $27P$ keeping all other quantities the same, the distance $x_1$ becomes $x_2$. The difference $|x_2 - x_1|$ is (All distances are measured from the centers of the dipoles.) (in $\text{ cm}$)