$512$ identical drops of mercury are charged to a potential of $2\, V$ each. The drops are joined to form a single drop. The potential of this drop is ......... $V.$

Three concentric metal shells $A, B$ and $C$ of respective radii $a, b$ and $c (a < b < c)$ have surface charge densities $+\sigma,-\sigma$ and $+\sigma$ respectively. The potential of shell $B$ is

In an hydrogen atom, the electron revolves around the nucleus in an orbit of radius $0.53 \times {10^{ - 10}}\,m$. Then the electrical potential produced by the nucleus at the position of the electron is......$V$

There are four concentric shells $A, B, C $ and $D $ of radii $ a, 2a, 3a$  and $4a$ respectively. Shells $B$ and $D$ are given charges $+q$ and $-q$ respectively. Shell $C$ is now earthed. The potential difference $V_A - V_C $ is : 

Value of potential at a point due to a point charge is

In the following figure two parallel metallic plates are maintained at different potential. If an electron is released midway between the plates, it will move