Two identical charges $Q$ are separated by a distance $r$. $A$ third charge $q$ is placed at the midpoint of the line joining the two charges such that all three charges are in equilibrium. In this state,$q = $ . . . . . . .

$A$ cube of side $b$ has a charge $q$ at each of its vertices. The electric field due to this charge distribution at the centre of this cube will be

Three point charges are placed at the corners of an equilateral triangle of side $L$ as shown in the figure.

Three point charges $q_1, q_2, q_3$ are placed at the vertices of a triangle. If the forces on $q_1$ and $q_2$ are $(2\hat{i} - \hat{j}) \, N$ and $(\hat{i} + 3\hat{j}) \, N$,respectively,then what will be the force on $q_3$?

The repulsive force between two point charges is $F$ when they are separated by a distance of $1 \, m$. Now,these point charges are replaced by spheres of radius $25 \, cm$ having the same charges. The distance between their centers is $1 \, m$. The repulsive force in the two cases will decrease according to:

Which of the following physical quantities have the same dimensions?