Suppose a charge of -2.10 µC is at the origin and a charge of 2.90 µC is at the point (0, 3.00) m.
(a) Find the electric potential at (4.00, 0) m, assuming the electric potential is zero at infinity.
(b) Find the work necessary to bring a 3.50 µC charge from infinity to the point (4.00, 0) m.