Solve the given problem:
Problem: Four point charges, each having a charge with a magnitude of 2.00 uC, are at the corners of a square whose sides are 4.00 m long. The charges at two opposite corners are positive and the other two charges are negative. (Assume the potential energy is zero when the point charges are very far from each other.)
Part A: Find the electrostatic potential energy of this system in mJ.
I need help to determine the electrostatic potential energy of this system in mJ.