Three concentric spherical metallic shells $A$,$B$,and $C$ of radii $a=7 \ cm$,$b=17 \ cm$,and $c$ $(a < b < c)$ have surface charge densities $\sigma, -\sigma$,and $\sigma$ respectively. If $A$ and $C$ are at the same potential,then the value of $c$ is: (in $cm$)

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

If on two concentric hollow spheres of radii $R$ and $r$ $(R < r)$,a total charge $Q$ is distributed such that their surface charge densities are equal,then the potential at their common centre is:

There is a uniform electrostatic field in a region. The potential at various points on a small sphere centered at $P$,in the region,is found to vary between the limits $589.0\,V$ to $589.8\,V$. What is the potential at a point on the sphere whose radius vector makes an angle of $60^o$ with the direction of the field (in $,V$)?

Draw a graph showing the variation of electric potential $V$ with distance $r$ from the center for a uniformly charged spherical shell of radius $R$.

The electric potential inside a charged hollow conducting sphere is . . . . . . .