Thundercloud **
You observe that the passage of a particular thundercloud over- head causes the vertical electric field strength in the atmosphere, measured at the ground, to rise to 3000 N/C (or V/m).
(a) How much charge does the thundercloud contain, in coulombs per square meter of horizontal area? Assume that the width of the cloud is large compared with the height above the ground.
(b) Suppose there is enough water in the thundercloud in the form of 1 mm diameter drops to make 0.25 cm of rainfall, and that it is those drops that carry the charge. How large is the electric field strength at the surface of one of the drops?