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From: mwg@petrus.UUCP (Mark Garrett)
Newsgroups: net.sci
Subject: Re: Question about Electricity
Message-ID: <678@petrus.UUCP>
Date: Fri, 8-Nov-85 09:57:37 EST
Article-I.D.: petrus.678
Posted: Fri Nov  8 09:57:37 1985
Date-Received: Wed, 13-Nov-85 04:11:46 EST
References: <621@hlwpc.UUCP> <662@petrus.UUCP> <2709@brl-tgr.ARPA>
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Organization: Bell Communications Research, Inc
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++
> Hmmm --- if a person is immersed in the water, why would they be
> electrocuted at all? If they were between the wire and the point of
> greatest ground potential, like a metal drain, I could see it (but
> wouldn't the current tend to flow AROUND the body, through the water
> which has less resistance than the body [considering skin resistance]).
> 
> If they were in the pool, at another spot, why would there be any
> potential across their body at all? They wouldn't have any current
> flow through their body in this case, would they?
> Will

When I was young(er), and before so many years of education in engineering
and electronics, I thought about what would happen if lightning hit the
house when I was in the shower.  I thought that I'd be safe since the current
would much rather go through the pipe (full of water) in the wall than
through me.  The problem with this logic is that the two resistances are
really in parallel (depending on the geometry).  If I constituted a path
with 1% of the total conductivity from the source to ground, then I
would get 1% of the current.  For lightning, even a small fraction of the
current might ruin one's day.

I can see that in the swimming pool case, the current density resulting from
a 120 volt drop, spread out over the water might be small.  But remember, that
the conductivity of the water is finite, so there is a voltage difference
between any two points along the current path.  Therefore if you are in
that path, you have some voltage across you and you will draw some current.