Question

There is 10 units of charge at the centre of a circle of radius 10 m. The work done in moving unit of charge once around the circle will be?

Answer 1

There is 10 units of charge at the centre of a circle of radius 10 m. The work done in moving unit of charge once around the circle will be?

answer : zero

explanation : workdone is given by, W = q∆V

where ∆V is potential difference of final position to initial position of charge particle of charge q.

but as you know, potential at any point of ring remains same. it is because distance between charge and observation point remains same.

so, potential difference, ∆V = $\frac{kq}{r}-\frac{kq}{r}=0$

then, workdone in moving unit of charge once around the circle will be zero.