PHYSICS · Multi-part · CBSE · Physics · Electrostatic Potential and Capacitance · Electrostatic Potential and Capacitance
Problem
During flight, a commercial airplane constructed primarily from aluminum is struck by lightning that deposits −40C of charge onto the aircraft in approximately 1.0ms. The fuselage can be approximated as a hollow conducting cylinder of length 40m and radius 3.0m. Assume the wings and tail together present an additional effective surface area equal to one-half of the fuselage’s lateral surface area.
(1) Immediately after the lightning strike, describe qualitatively how the deposited charge redistributes itself over the external surface of the airplane. Explain the physical principles that govern this redistribution.
(2) Explain why passengers and sensitive electronic equipment inside the airplane experience negligible electric fields during and after the strike, even though a large amount of charge is present on the exterior surface.
(3) Using the geometric model provided, estimate the average surface charge density on the external skin of the airplane immediately after the strike. State clearly any approximations you employ.
(4) Moist air surrounding the aircraft permits a small, approximately steady leakage current of 20mA that carries charge away from the airplane. Assuming this current remains constant and the airplane receives no additional charge, estimate the time required for the net charge on the airplane to decrease to −1.0C. Show your reasoning.