Re: An ohmic experiment

[Gary Karshner <karshner@STMARYTX.EDU>]

> That's as clear an answer as I've ever gotten. Thanks, Michael. Now, let's
generalize a
> bit. Aside from the intentionally non-ohmic devices that have been
mentioned in this
> thread, are most substances (homogeneous elements and compounds) ohmic in
the sense of
> your result (1)?
Paul,
        Au contraire, as my solid state physics professor put it: "Ohm law is a
poor physical law since it holds for a limited class of materials over a
limited temperature range." Most substances are insulators which are very
non-ohmic in their conduction. Where as Ohm's law only holds for metals and
then only if the temperature is held constant.
        I remember after graduating high school a friend went into the Army and
coming back from electronics school wanted to know where he could find a
whole book on Ohm's law. He felt there must be one since it was so
important and difficult! As a former electrical engineer I can attest that
the most of that industry runs on that "poor law" which I guess shows as
how powerful a poor approximation to nature can be. Most of our other
physical properties of materials are just as bad if not worse an
approximation.

Gary

Gary Karshner

St. Mary's University
San Antonio, Texas
KARSHNER@STMARYTX.EDU