- #1
kaotak
I've looked this up extensively on the web but nothing seems to answer this question satisfactorily. For example, here's Wikipedia's answer.
I try thinking of it considering the properties of a conductor in electrostatic equilibrium. The charge on a conductor in equilibrium resides on the surface and the electric field is zero inside. Okay...
But once lightning hits a metal cage with a person inside, isn't the cage momentarily NOT in electrostatic equilibrium? Isn't the cage not in electrostatic equilibrium until the charges are done redistributing themselves, and in this period of time, won't the person inside be fried?
A Faraday cage is best understood as an approximation to an ideal hollow conductor. Externally applied electric fields produce forces on the charge carriers (usually electrons) within the conductor, generating a current that rearranges the charges. Once the charges have rearranged so as to cancel the applied field inside, the current stops.
The cage will block external electrical fields even if the cage contains some charges and an electric field in its interior. This is a consequence of the superposition principle and the fact that the Maxwell equations are linear.
I try thinking of it considering the properties of a conductor in electrostatic equilibrium. The charge on a conductor in equilibrium resides on the surface and the electric field is zero inside. Okay...
But once lightning hits a metal cage with a person inside, isn't the cage momentarily NOT in electrostatic equilibrium? Isn't the cage not in electrostatic equilibrium until the charges are done redistributing themselves, and in this period of time, won't the person inside be fried?