Capacitance of a Thundercloud The charge center of a thundercloud, drifting 3.0 km above the earth's surface, contains 20 C of negative charge. Assuming the charge center has a radius of 1.0 km, and modeling the charge center and the earth's surface as parallel plates, calculate:
(a) The capacitance of the system;
(b) The potential difference between charge center and ground;
(c) The average strength of the electric field between cloud and ground;
(d) The electrical energy stored in the system.