Question

what is the potential energy of 4 point charges each of value Q at the corners of a square of side length a.

Answer 1

potential energy is a function of distance from the charges. Where do you want it?

Answer 2

at the centre or one of corners

Answer 3

Well, at a corner it is infinite since we have that division by zero problem when r = 0

at the middle, find the potential of one of them at a distance of (a/2)sqrt 2

The neat thing about potentials is that they add like scalars. Just multiply by 4.

Answer 4

so it will be kq(4Q/a/2)

Answer 5

Suspect so :)

Answer 6

4kqq/r^2