Tuesday, May 13, 2008

Getting struck by lightning

Excellent piece in today's Science Times about how to get struck by lightning and live: do it while inside a Faraday Cage.

A Faraday Cage is a metal container that takes advantage of the following effect in electro- magnetism: If a conductor (e.g. a metal container) is put in an electric field, the electrons in the conductor move according to the forces from the field until they are in equilibrium (meaning that any further movements would increase the electrical potential energy of the charges).

This allocation of charges also has the effect of creating a field that exactly counters the external field. The effect of this is that inside the Faraday Cage there is effect from the external field. So, if a large charge were transferred to the surface of the cage (e.g., from lightning), the charges on the surface would reorient themselves in a new way that exactly cancelled out the external force, leaving anything in the cage unaffected by the charge surge.

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