Two identical positive charges are placed at $x =\, -a$ and $x = a$ . The correct variation of potential $V$ along the $x-$ axis is given by

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 : 

Four charges of $1\  \mu C, 2\  \mu C, 3\  \mu C,$ and $- 6\ \mu C$ are placed one at each corner of the square of side $1\,m$. The square lies in the $x-y$ plane with its centre at the origin.

Twenty seven drops of water of the same size are equally and similarly charged. They are then united to form a bigger drop. By what factor will the electrical potential changes.........$times$

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

Consider a finite insulated, uncharged conductor placed near a finite positively charged conductor. The uncharged body must have a potential