When lightning strikes a car, the metallic outer shell, which isinsulated from the ground by its rubber tires, attains a high voltage. We canestimate how much charge is deposited by roughly modeling the car as aspherical capacitor with the outer radius taken to infinity. Determine the capacitance of a sphere in terms of its radius, either by considering the potential on a sphere relative to infinity as a function of its charge, or by considering a spherical capacitor as the outer shell becomes very large. (These methods provide the same result.)

When lightning strikes a car, the metallic outer shell, which isinsulated from the ground by its rubber tires, attains a high voltage. We canestimate how much charge is deposited by roughly modeling the car as aspherical capacitor with the outer radius taken to infinity. Determine the capacitance of a sphere in terms of its radius, either by considering the potential on a sphere relative to infinity as a function of its charge, or by considering a spherical capacitor as the outer shell becomes very large. (These methods provide the same result.)