The radius of a soap bubble whose potential is $16\,V$ is doubled. The new potential of the bubble will be.....$V$

$N$ identical spherical drops charged to the same potential $V$ are combined to form a big drop. The potential of the new drop will be

Twenty seven drops of water of the same size are equally and similarly charged. They are then united to form a bigger drop. By what factor will the electrical potential changes.........$times$

Concentric metallic hollow spheres of radii $R$ and $4 R$ hold charges $Q _{1}$ and $Q _{2}$ respectively. Given that surface charge densities of the concentric spheres are equal, the potential difference $V ( R )- V (4 R )$ is

In a certain charge distribution, all points having zero potential can be joined by a circle $S$. Points inside $S$ have positive potential and points outside $S$ have negative potential. A positive charge, which is free to move, is placed inside $S$

Write an equation for potential due to linear charge distribution.