This is probably a good place to mention that people interested in the
relationship between RMS voltage and current and average power (and the
uselessness of the RMS value of power) can find an explanation at
http://eznec.com/Amateur/RMS_Power.pdf. It doesn't use any mathematics
more advanced than a square and square root, so any amateur should be
able to understand it.

Some time ago I was surprised to find this to be one of the most
frequently visited pages at my web site, apparently due to a link in the
Wikipedia entry for RMS.

Roy Lewallen, W7EL