An electrostatic paint sprayer has a metal sphere of diameter $18 \, cm$ and at a potential of $25 \, kV$. The charge on the metal sphere is: (in $ \, \mu C$)

In the following diagram, the work done in moving a point charge from point $P$ to points $A, B$ and $C$ is $W_A, W_B$ and $W_C$ respectively. If there is no charge nearby, then:

$A$ total charge $Q$ is distributed between two concentric spherical shells of radii $r$ and $R$ $(R > r)$ such that their surface charge densities are equal. What is the electric potential at their common center?

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:

Two identical thin rings,each of radius $R \text{ m}$,are coaxially placed at a distance $R \text{ m}$ apart. If $Q_1$ and $Q_2$ coulombs are the charges uniformly spread on the two rings respectively,the work done in moving a charge $q$ from the centre of one ring to that of the other is

The electric potential inside a conducting sphere: