The force acting between two point charges `q_1` and `q_2` kept at the same distance apart in air is attractive or repulsive when `q_1q_2<0`.

The force of attraction between two point charges placed at a distance 'd' apart in a medium is F. what should be the distance apart in the same medium so that the force of attraction between them becomes F/4 ?

Write the vector form of force acting between two charges q_1 and q_2 having vec r_1 and vec r_2 as their position vectors respectively.

Force between two point electric charges kept at a distance of r in air is F. if these charges are kept at the same distance in water, how does the force between them change?

Two point charges q_1 and q_2 are kept at a distance of r_(12) in air. Deduce the expression for the electrostatic potential energy of the system.

Two point charges q1 and q2 are kept at a distance of r12 in air..If an external electric field is applied on the system, write the expression for the total energy of this system.