Two point charges, 4.0×10-6 C and -1.0×10-6 C, are located on the x axis at = -1.0 cm and = 3.0 cm.
(a) Determine the electric field at the origin.
(b)Determine the x coordinate of a point on the positive x axis where the electric field is zero; i.e., a test charge placed at this point would experience no force.