Why is the work done in moving a charge around a circular path zero?

[Crystal037]

Homework Statement

Why the work done in moving a charge around any circular path inside which another point charge is kept at its centre is 0? Shouldn't it need some kind of torque? If there is no work done then the charge should keep revolving

Relevant Equations

W=delta(V)q

Work done in moving a charge around the circular path is 0 because the distance between the charges remain the same so there is no potential difference and delta(V)=0 but I thinkk some torque or external force must be required to move the charge around the circula path

 

[Doc Al]

The work done by the electric force is zero because that force acts at 90 degrees to the direction of motion. (For work to be done by a force, that force must have a component in the direction of the displacement.) There may or may not be other forces involved, but they are not needed.

(Think of a satellite in a circular orbit around the earth. Gravity pulls it in a circle but does no work. And no other forces are needed to maintain that orbit.)