Consider the earth and a cloud layer 800 m above the earth to be the
plates of a parallel-plate capacitor. (a) If the cloud layer has an area
of 1.0 square kilometers = one million square meters, what is the
capacitance? (b) If an electric field strength of two million N/C causes
the air to break down and conduct charge (lightning), what is the maximum
charge the cloud can hold?
