Write an equation for an electrostatic potential of a negative point charge. 

A solid conducting sphere, having a charge $Q$, is surrounded by an uncharged conducting hollow spherical shell. Let the potential difference between the surface of the solid sphere and that of the outer surface of the hollow shell be $V$. If the shell is now given a charge of $-4\, Q$, the new potential difference between the same two surface is......$V$

The potential at a distance $R/2$ from the centre of a conducting sphere of radius $ R$ will be

A hollow metal sphere of radius $5\, cm$ is charged so that the potential on its surface is $10\, V$. The potential at the centre of the sphere is

In a uniform electric field, the potential is $10$ $V $ at the origin of coordinates, and $8$ $V$ at each of the points $(1, 0, 0), (0, 1, 0) $ and $(0, 0, 1)$. The potential at the point $(1, 1, 1)$ will be....$V$

Find the equation of the equipotential for an infinite cylinder of radius ${{r_0}}$, carrying charge of linear density $\lambda $.