I think most people at sometime or another heard the sound an Amplifier makes when you touch the input lead, that sort of Burrrrrrr, sound.

I`de like to know what causes it? now at 1`st the answer may seem simple but for a few reasons.

the same sound occurs even on battery powered amps in the middle of nowhere. the sound is always the same frequency too? about 50 to 60Hz ish. that made me wonder if it was something to do with mains electricity around the Earth. or maybe the fact that were struck by lightening about 50 times per second at least somewhere on Earth at any given time (but the frequency seems to constant for that to be possible). It occurs on ships in the middle of the sea too.

would the same be heard in the space station ?

 

any ideas?

Touch a probe of an oscilloscope then you will see the signal.

(a sinus that has some extra smaller signals on it)

50Hz in Europe 60Hz in America.

(power electricity cables)

You are an conductor in a magnetic/electric field, like an antenna.

how does it work on a boat in the sea though? or when we go camping and used a battery amp?

is it that the 56/60 Hz wavelength is so long that we can`t escape it on Earth?

and would it happen in a Faraday cage?