For a dipole with charge $q = 2 \times 10^{-6} \, C$ and separation $d = 0.01 \, m$,calculate the maximum torque acting on this dipole if it is placed in an electric field $E = 5 \times 10^5 \, N/C$.

Assertion $:-$ An electric dipole experiences maximum force in a uniform electric field,when it is placed with its axis at right angles to the field direction.
Reason $:-$ When the axis of a dipole is perpendicular to a uniform external electric field,then torque acting on it will be zero.

Two charged particles each of mass $9.8 \text{ g}$ and charges $+20 \mu\text{C}$ and $-20 \mu\text{C}$ are attached to the two ends of a massless and rigid uniform non-conducting rod of length $50 \text{ cm}$. This arrangement is held in a uniform electric field of $12.1 \text{ N/C}$,such that the rod makes a very small angle with the field direction. If the rod is set free,the minimum time needed for the rod to become parallel to the direction of the electric field is ................ seconds.

Obtain the expression for the torque acting on an electric dipole in a uniform external electric field.

Two charges of $+25 \times 10^{-9} \, C$ and $-25 \times 10^{-9} \, C$ are placed $6 \, m$ apart. Find the ratio of the electric field intensity at a point $4 \, m$ from the center of the electric dipole on the $(i)$ axial line and $(ii)$ equatorial line.

$A$ point electric dipole placed at the origin has a potential given by $V(r, \theta) = \frac{p \cos \theta}{4 \pi \varepsilon_0 r^2}$,where $\theta$ is the angle made by the position vector with the direction of the dipole. Then,