$1000$ small water drops each of radius $r$ and charge $q$ coalesce together to form one spherical drop. The potential of the big drop is larger than that of the smaller drop by a factor of

Two charges ${q_1}$ and ${q_2}$ are placed at $(0, 0, d)$ and$(0, 0, - d)$ respectively. Find locus of points where the potential is zero.

Do free electrons travel to region of higher potential or lower potential ?

Six point charges are placed at the vertices of a regular hexagon of side $a$ as shown. If $E$ represents electric field and $V$ represents electric potential at $O$, then

Two spheres $A$ and $B$ of radius $a$ and $b$ respectively are at same electric potential. The ratio of the surface charge densities of $A$ and $B$ is

$512$ identical drops of mercury are charged to a potential of $2\, V$ each. The drops are joined to form a single drop. The potential of this drop is ......... $V.$