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From: jeffw@midas.WR.TEK.COM (Jeff Winslow)
Newsgroups: rec.boats,sci.physics,sci.electronics
Subject: Re: St Elmo's Fire - 100 v/m ?
Message-ID: <3067@wrgate.WR.TEK.COM>
Date: 25 Jul 90 06:27:48 GMT
References: <1990Jul18.111525.5749@ioe.lon.ac.uk> <richard.648454274@snap.la.locus.com> <5498.26aba906@cerritos.edu>
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Reply-To: jeffw@midas.WR.TEK.COM (Jeff Winslow)
Followup-To: rec.boats
Organization: Tektronix, Inc., Beaverton,  OR.
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|> Here's the real scoop (source: The Feynman Lectures on Physics, Vol 2,
|> chapter 9).  Away from thunderclouds, the earth has a negative charge
|> relative to "the sky."  The potential difference is quite incredible:
|> about 100 volts per meter.  Why does this not electrocute you?  Because
|> your skin is so much better at conducting than air, your skin can be
|> treated as a perfect conductor.  Your head and your feet have the same
|> potential as the earth.  A foot from your nose, the air is at a potential
|> of +200V.
|
|Just curious...
|Why can't this be measured with a DVM?

Because that 10 megohm input DVM is also a much better conductor than air.

Maybe with something like an electrometer... ??

						Jeff Winslow