Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!munnari.oz.au!metro!otc!brendan
From: brendan@otc.otca.oz (Brendan Jones)
Newsgroups: sci.electronics
Subject: 3dB rolloff of a human (was Re: HELP!)
Message-ID: <2204@otc.otca.oz>
Date: 28 Jan 91 21:43:02 GMT
References: <20472@hydra.gatech.EDU>
Lines: 30

Talking about using the human body as a conductor...

I once saw a little 10 minute film made in the '50s late at night on TV.
The film was actually about religion, but to make a point, the narrator
made a most remarkable demonstration.

In the studio, they had a Van Der Graff generator (I think), a horizontal
circular anode that acted as a platform and about three metres above that 
a pointed cathode.

The generator was said to deliver 1 million volts EMF at a frequency of
20 kHz.  The narrator then put on pointed thimble caps on the ends of
each finger (to prevent corona discharge burning the ends of his fingers),
grabbed a bit of 4x2, stood on the anode, and held the wood up to the
cathode.

The million volts arced across from the wood to the cathode (a distance of
about 20 cm) and the wood burst into flames.  All the while, he was talking
and making some deep and meaningful observations.

So it goes to show that EMF is not the killer.  Current is, but obviously
the body is a low pass filter and must have high attenuation at 20 kHz.
So what is the 3dB rolloff?  I suspect around 100 Hz which is why 50 Hz
is such a killer.

-- 
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