For a hollow spherical shell,how does the potential $(V)$ change with respect to the distance $(r)$ from the centre?

$A$ sphere with charge $Q$ is placed concentrically inside an uncharged spherical shell. The potential difference between them is $V$. Now,if a charge of $-3Q$ is given to the spherical shell,what will be the potential difference between them?

$A$ solid conducting sphere with charge $Q$ is surrounded by an uncharged concentric conducting spherical shell. Let $V$ be the potential difference between the surface of the solid sphere and the outer surface of the shell. If the shell is now given a charge of $-3Q$,the new potential difference between the two surfaces is .........$V$.

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

$A$ solid sphere of radius $R$ is charged uniformly. At what distance from its surface is the electrostatic potential half of the potential at the centre?

$A$ point charge $q$ is held at the centre of a circle of radius $r$. $B$ and $C$ are two points on the circumference of the circle,and $A$ is a point outside the circle. If $W_{AB}$ represents the work done by the electric field in taking a charge $q_0$ from $A$ to $B$,and $W_{AC}$ represents the work done from $A$ to $C$,then: