Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!elroy.jpl.nasa.gov!turnkey!orchard.la.locus.com!fafnir.la.locus.com!dana
From: dana@locus.com (Dana H. Myers)
Newsgroups: sci.electronics
Subject: RMS versus pk-pk (was Re: polarity)
Summary: Repeating wrong information does not make it right
Message-ID: <1991Apr26.233212.2806790@locus.com>
Date: 26 Apr 91 23:32:12 GMT
References: <11864@jarthur.Claremont.EDU> <1991Apr23.152315.22825@news.larc.nasa.gov> <1991Apr24.111307.2296@dcs.simpact.com> <2226@gold.gvg.tek.com> <1991Apr26.035007.2804716@locus.com> <00947B34.A08BA800@COED.COASTAL.UFL.EDU>
Distribution: usa
Organization: Locus Computing Corporation, Inglewood, CA
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I wrote:
    I know I'm the one who claimed that power is dissipated in capacitors a
  while back (ugh!), but I do not believe 120VRMS is 340V p-p. It is 170V p-p.

To which sidney@coed.coastal.ufl.edu replied:
  The 120vrms power is 340v p-p.  The voltage equation for our 120 volt
  system is 120*sin(377t).  The rms value is the square root of the integral
  of the voltage squared over a full period.  For sine wave voltages this
  works out to .707 * the peak voltage.  For 120vrms power this is
  .707 * 170 = 120 volts.  The 170 volt peak voltage occurs on both the 
  positive and negative portions of the sin wave.  Thusly the peak to peak 
  voltage is 340V not 170.

And now I write:

  Oh goodness, I've done it again. 

-- 
 * Dana H. Myers KK6JQ 		| Views expressed here are	*
 * (213) 337-5136 		| mine and do not necessarily	*
 * dana@locus.com		| reflect those of my employer	*