A spherical conductor of radius $2\,m$ is charged to a potential of $120\,V.$ It is now placed inside another hollow spherical conductor of radius $6\,m.$ Calculate the potential to which the bigger sphere would be raised......$V$

Derive an expression for the electric potential in a electric field of positive point charge at distance $\mathrm{r}$.

Prove that, if an insulated, uncharged conductor is placed near a charged conductor and no other conductors are present, the uncharged body must be intermediate in potential between that of the charged body and that of infinity.

Four charges $ + Q,\, - Q,\, + Q,\, - Q$ are placed at the corners of a square taken in order. At the centre of the square

Two unlike charges of magnitude $q$ are separated by a distance $2d$. The potential at a point midway between them is

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.........$times$