Lightning

The static discharges of lightning produce static interference on a AM radio that will overwhelm the reception of a station on a simple radio receiver. This is propagated electromagnetic waves from the lightning, stronger at the lower frequencies. Less amplitude at the higher frequencies. For big discharges near by - a low frequency electromagnetic pulse (EMP) is generated that could produce some large changing magnetic fields - this induces a strong current in any conductor present (the longer the conductor the higher the voltage) and in the past could potentially harm sensitive receivers and electronics equipment. This is not so much the case these days with the tougher hardened electronics available. However, to be safe some shielding could be used. So if sensitive equipment is hidden away in a highly magnetic and electrical conductive box then no current will be induced - thus the protection. This is just a bonus not the main thing we are tying to shield for.

Offered by Mike.