The electric potential inside a conducting sphere:

Two point charges $-q$ and $+q$ are located at points $(0,0,-a)$ and $(0,0, a)$ respectively. The electric potential at a point $(0,0, z)$,where $z>a$ is

$A$ uniformly charged half-ring of radius $R$ has a linear charge density $\sigma$. The electric potential at the centre of the half-ring is ($\epsilon_0$ = permittivity of free space).

Three concentric spherical shells have radii $a, b$ and $c$ $(a < b < c)$ and have surface charge densities $\sigma, -\sigma$ and $\sigma$ respectively. If $V_A, V_B$ and $V_C$ denote the potentials of the three shells,then,for $c = a + b$,we have

Two points $P$ and $Q$ are at potentials of $10 \ V$ and $-4 \ V$ respectively. The work done in moving $100$ electrons from $P$ to $Q$ is .....

$729$ small identical spheres each charged to an electric potential $3 \ V$ combine to form a bigger sphere. The electric potential of the bigger sphere is (in $V$)