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Re: funny capacitor



----- Original Message -----
From: "John S. Denker" <jsd@MONMOUTH.COM>
To: <PHYS-L@lists.nau.edu>
Sent: Tuesday, March 06, 2001 10:59 AM
Subject: Re: funny capacitor


At 10:33 AM 3/6/01 -0500, Bob Sciamanda wrote:
The "full" (your term) capacitance matrix Cij which you are defining
restricts the validity of the equation Qi=SUM CijVj to states with the
same total charge, SUM Qi.

I consider that a feature, not a bug. It makes manifest the law of
conservation of charge.

There is no one set of Cij that is a property
only of geometry and the choice of voltage reference point.

Au contraire, the full capacitance matrix Cij depends only on geometry,
and
it is independent of choice of voltage reference point.


The point is that your "full" matrix Cij DOES depend upon the total system
charge, and so is not a unique and purely geometric system property
connecting all possible charge/potential combinations (a property whose
value can be stamped on the system). You have sold this universality for
gauge invariance and charge conservation (by simply restricting its
validity to such cases).

Bob Sciamanda
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor