Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site ttrdc.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!ihnp4!mgnetp!ltuxa!ttrdc!levy From: levy@ttrdc.UUCP (Daniel R. Levy) Newsgroups: net.sci Subject: Re: Question about Electricity Message-ID: <554@ttrdc.UUCP> Date: Sat, 2-Nov-85 18:45:01 EST Article-I.D.: ttrdc.554 Posted: Sat Nov 2 18:45:01 1985 Date-Received: Sun, 3-Nov-85 09:17:56 EST References: <621@hlwpc.UUCP> <662@petrus.UUCP> <714@alberta.UUCP> Distribution: net Organization: AT&T, Computer Systems Division, Skokie, IL Lines: 33 In article <714@alberta.UUCP>, makaren@alberta.UUCP (Darrell Makarenko) writes: > > I remember doing experiments in grade 12 science showing > that pure water does not conduct electricity. Salt water did conduct > because of the Na+ and Cl- ions. Of course air does not conduct > electricity either but lightning still hits the ground. > Question: Does pure water conduct electricity? If it does not > (as I believe) why does one have to be extra carefull about getting > elecrocuted when standing in a puddle of water?? If you had tested tap water too you would have found it to be a pretty fair conductor. It doesn't take much impurities to do this. You can pretty well count on all naturally occurring water to have enough impurities to be a good enough conductor to allow dangerous amounts of current to pass at house- hold power voltages, given the usual small distance in the puddle between your skin and a good conductor, namely the ground, at an opposite potential to a "live" wire (since most electrical systems have one side of their voltage source tied to an earth ground somewhere). You touch the other side of the voltage source while standing in such a puddle, and you get shocked or worse. The lightning mechanism is different. The voltage difference between cloud and ground or cloud and cloud is sufficient to ionize the air, whereupon it WILL conduct electricity (very simplistic explanation; the ionization occurs in steplike stages) sort of like neon does in a neon lamp. Now the question of how the cloud achieves that voltage is a different one and I understand there are several explanations (anyone care to elaborate?). -- ------------------------------- Disclaimer: The views contained herein are | dan levy | yvel nad | my own and are not at all those of my em- | an engihacker @ | ployer or the administrator of any computer | at&t computer systems division | upon which I may hack. | skokie, illinois | -------------------------------- Path: ..!ihnp4!ttrdc!levy