Question

A positive charge q is moved on another charge q on a circular path with the radius of the circular path is our work done on the charge q in making one complete revolution is

Answer 1

The work done is zero. Because work done by conservative force, in this case, electrostatic force, is equal to negative of change in potential energy which is zero as the potential energy is constant throughout the motion and is equal to $k q_{1 } q_{2} /r$