If a test charge is moved on equipotential surface from one point to another, what will be the amount of work done ?

If a test charge is moved on equipotential surface from one point to another, what will be the amount of work done ?

a. equal to unity
b. greater than unity
c. less than unity
d. zero

Correct Answer : d. zero

Explanation :

Charge on any equipotential surface is independent of position & hence the net work done by the test charge is absolutely equal to zero.