Re: [ Re: Variable Capacitance and Inductance]]

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:

> > Give me the name of one machine that measures capacitance or
> 
> > inductance directly.  This would be of great interest to
> > learn about.

	That's easy!  Take a good look at any textbook on electrical
measurements.  It would be a good idea to search the web site of the
National Institute of Standards and Technology (www.nist.gov) for a
description of how fundamental standards of inductance and capacitance
are measured and maintained.  Accuracies and REPEATABILITY are of the
order of a part in a million.  The measurements are made in terms of the
fundamental definitions of the units involved.  I personally would
recommend a fascinating little book called: "Great Experiments in
Physics: From Galileo to Einsten" by Morris Shamos; it's a bargain at
only $10.36, and should be in the library of anyone interested in
science.  On the question of capacitance in particular look at the
description of Coulomb's experiments.  Contains descriptions of
experiments of Ampere and Faraday, among other things.  You might be
particularly interested in the description of how Cavendish measured the
gravitational force of the earth, about 1790!!!!  Beautifully thought
out experiment which gave surprisingly accurate results.  As part of the
description there are Cavendish's own words on how he got rid of all
sorts of experimental error, something which is most important in any
good experiment.

Ed