Question

Derive the expression for potential energy of a system of two charges in the absence of the

external electrical field

​

Answer 1

EXPLANATION

Consider a system of two point charges

Q1 and Q2 and separated by a distance r.

The work done to move Q1 from infinity to

a =W1 = 0

The work done to move Q2 from infinity to

b = W2 = 0

There is no initial electric field

The potential energy of this system of charges is equal to the work done

to build this configuration

U = W1 + W2 = 0