A metal sphere of radius 19 cm has a net charge of 4.0×10−8 C. (a) What is the electric field at the sphere's surface? (b) If V = 0 at infinity, what is the electric potential at the sphere's surface? (c) At what distance from the sphere's surface has the electric potential decreased by 300 V? (a) Number Units (b) Number Units (c) Number Units