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

$A$ point charge $q$ is surrounded symmetrically by six identical charges each of magnitude $q$ at a distance $r$ as shown in the figure. How much work is done by the forces of electrostatic repulsion when the point charge $q$ at the centre is moved to infinity?

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$)

Two rings of radius $R$ are placed coaxially at a distance $R$ apart. They carry charges $Q_1$ and $Q_2$ respectively. How much work is required to move a charge $q$ from the center of one ring to the center of the other?

$A, B$ and $C$ are three points in a uniform electric field as shown in the figure. The electric potential 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....$V$