Question

Calculate the work done when a point charge is moved in a circle of radius r
around a point charge q.

Answer 1

work done in an equipotential surface is zero

Answer 2

Calculate the work done when a point charge is moved in a circle of radius r

Calculate the work done when a point charge is moved in a circle of radius raround a point charge q.

answer : workdone = zero

explanation : we know, potential difference between any two points on circumference of the circle is zero because circle is an equipotential surface.

so, potential difference, ∆V = 0

now, workdone when a point charge is moving in the circle , W = q∆V

= q × 0

= 0

hence, workdone = 0