Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site petrus.UUCP Path: utzoo!linus!philabs!cmcl2!seismo!lll-crg!ucdavis!ucbvax!decvax!bellcore!petrus!mwg 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> Distribution: net Organization: Bell Communications Research, Inc Lines: 27 ++ > 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.