When a charge of $20 C$ is taken from one point to another separated by a distance of $0.2 m$,work of $2 J$ is required to be done. What is the potential difference between the two points?

Two positive charges $Q$ and $4Q$ are placed at points $A$ and $B$ respectively, where $B$ is at a distance $d$ units to the right of $A$. The total electric potential due to these charges is minimum at point $P$ on the line segment joining $A$ and $B$. What is the distance of $P$ from $A$?

Two charges $q_1$ and $q_2$ are placed at $(0, 0, d)$ and $(0, 0, -d)$ respectively. Find the locus of points where the potential is zero.

Three concentric metallic shells $A, B$ and $C$ of radii $a, b$ and $c$ $(a < b < c)$ have surface charge densities $\sigma, -\sigma$ and $\sigma$ respectively. Find the potentials ${V_A}$ and ${V_B}$.

$A$ regular hexagon of side $6 \ cm$ has a charge of $2 \ \mu C$ at each of its vertices. What is the potential at the centre of the hexagon? $\left[\frac{1}{4 \pi \epsilon_0}=9 \times 10^9 \text{ SI units}\right]$

The electrostatic potential energy of the given system of charges placed at the corners of a square of side $a$ is: