Point charges of equal magnitudes (25nC) and opposite signs are placed on diagonally opposite corners of a

Question:

Point charges of equal magnitudes (25nC) and opposite signs are placed on diagonally opposite corners of a 60 cm x 80 cm rectangle. Point A is the unoccupied corner nearest the positive charge, and point B is the other unoccupied corner. Determine the potential difference VB – VA.