Question

A point charge \( q \) is rotated along a circle in the electric field generated by another point charge \( Q \). The work done by the electric field on the rotating charge in one complete revolution is:

• A. zero
• B. positive
• C. negative
• D. zero if the charge \( Q \) is at the centre and nonzero otherwise

Hint:

In circular motion, if the electric field force is perpendicular to the displacement, no work is done on the charge.

Answer 1

The Correct Option is A

Step 1: Electric field and work done.
The work done by an electric field on a charge is given by: \[ W = \vec{F} \cdot \vec{d} \] where \( F \) is the force and \( d \) is the displacement. In a circular motion, the force is always perpendicular to the displacement, implying no work is done. Step 2: Conclusion.
Since the electric field does no work on a charge moving along a circle with a perpendicular direction of motion, the total work done is zero.
Final Answer: \[ \boxed{0} \]