Eight equal charges $q$ are placed at each corner of a cube of side $a$. The work done in carrying a charge $-q$ from its centre to infinity is:

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?

$1 \ eV = ...... \ J$. (Fill in the gap)

$A$ charge $(-q)$ and another charge $(+Q)$ are kept at two points $A$ and $B$ respectively. Keeping the charge $(+Q)$ fixed at $B$,the charge $(-q)$ at $A$ is moved to another point $C$ such that $ABC$ forms an equilateral triangle of side $l$. The net work done in moving the charge $(-q)$ is

If the electric potential of the inner shell of radius $a$ is $10\,V$ and that of the outer shell of radius $2a$ is $5\,V$,then the potential at the centre will be.....$V$

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 ${V_B}$.