$A$ regular hexagon of side $10 \; cm$ has a charge $5 \; \mu C$ at each of its vertices. Calculate the potential at the centre of the hexagon.

$A$ charge of $10 \, \text{esu}$ is placed at a distance of $2 \, \text{cm}$ from a charge of $40 \, \text{esu}$ and at a distance of $4 \, \text{cm}$ from another charge of $-20 \, \text{esu}$. The potential energy of the $10 \, \text{esu}$ charge in ergs is:

Two electric charges $12\,\mu C$ and $-6\,\mu C$ are placed $20\, cm$ apart in air. There will be a point $P$ on the line joining these charges and outside the region between them,at which the electric potential is zero. The distance of $P$ from the $-6\,\mu C$ charge is.......$m$.

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.

An electric charge $10^{-3} \mu C$ is placed at the origin of $x-y$ plane. The potential difference between points $A$ and $B$ located at $(\sqrt{2} m, \sqrt{2} m)$ and $(2 m, 0 m)$ respectively is (in $V$)

The electric potential at a point at a distance $x$ from the center inside a conducting sphere of radius $R$ charged with charge $Q$ is: