Two identical positive charges are placed on the $y$-axis at $y=-a$ and $y=+a$. The variation of $V$ (electric potential) along $x$-axis is shown by graph

A regular hexagon of side $10\; cm$ has a charge $5 \;\mu\, C$ at each of its vertices. Calculate the potential at the centre of the hexagon.

Two concentric hollow metallic spheres of radii $r_1$ and $r_2 (r_1 > r_2)$ contain charges $q_1$ and $q_2$ respectively. The potential at a distance $x$ between $r_1$ and $r_2$ will be

If eight identical drops are joined to form a bigger drop, the potential on bigger as compared to that on smaller drop will be

A hollow conducting sphere of radius $R$ has a charge $( + Q)$ on its surface. What is the electric potential within the sphere at a distance $r = \frac{R}{3}$ from its centre

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