Question

Work done in carrying a 2 coulmb charge in a circular orbit of radius 3 m around a charge of 10 coulomb is?

Answer 1

W=qdv. dV=change in potential
Here in a circular orbit of r=3 potential at every point is same so
dV=0
W=q0=0

Answer 2

The overall work performed in carrying a 2 coulmb charge in a circular orbit of radius 3 m around a charge of 10 coulomb is calculated below.

It is a well-known fact that W=qdv.

Here dV is the change in overall potential. In the circular orbit of r potential at each point is similar.

Most significantly, the value of r is 3.  

The value of dv=0 and hence W=q0=0.