MadSci Network: Physics

Re: Why do power lines make a crackling sound?

Area: Physics
Posted By: Frank Berauer, Grad student Microelectronics Centre
Date: Wed Jul 9 00:17:19 1997
Area of science: Physics
ID: 867873781.Ph
Loudspeakers are optimized to only create acoustic waves of frequencies
supplied by the electric current. All other waves they create are noise.
The better they are optimized, the less noise they create.
Not surprising, a power line, which is not optimized in such a way,
creates more noise than frequency of the current (which is 50Hz in most
parts of the world). I suppose that's the "white noise" you described.
An occasional crackling sound could come from athmospheric discharges of
static electricity, but this should only occur near very high voltage
lines that are not usually near appartments (for safety reasons).

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