From: Art Fortgang (afortga@smcoe.k12.ca.us)
Date: Sun Apr 16 2000 - 07:45:15 PDT
Message-ID: <000701bfa7b2$6155e660$6680bcd1@mocha> From: "Art Fortgang" <afortga@smcoe.k12.ca.us> Subject: Re: Pinhole Digest #392 - 04/16/00 Date: Sun, 16 Apr 2000 07:45:15 -0700
In Don's reply he quotes from a source:
Ground Fault Circuit Interrupter (GFCI). A safety circuit breaker that
compares the amount of current entering a receptacle with the amount
leaving.
If there is a discrepancy of 0.005 volt, the GFCI breaks the circuit in 1/40
of a second. Usually required by code in areas that are subject to
dampness."
The first part of the arguement talks about current, while the second part
discusses a measurement of voltage. I know we understand what is being said
here, but this is the source of origin of student misconceptions. The first
part while
discussing current and the implied flow follows that with "a discrepancy of
"0.005
volts". Perhaps they really mean 0.005 amps. However it could mean 0.005
volts. Either way, as written, this will lead students to believe that
voltage flows-
a misconception that probably lasts a lifetime!
Don's discussion is an excellent answer to GFCI's "why not the pickle but
us"?
Art
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