Three point charges with values q1 = 8.00 nc , q2 = 1.00 nc , and q3 = 5.00 nc are placed on three consecutive corners of a square whose side measures s = 5.00 m . point a lies at the fourth corner of the square, diagonally across from q2. point b lies at the center of the square. what are the values of the electric potential at point a and at point b? how much energy (supplied as work) is required to move a test charge q4 = 2.00 nc from point a to point b? assume the zero of electric potential is chosen to be at infinity.