Re: non-potential voltage

["John S. Denker" <jsd@MONMOUTH.COM>]

1) At 10:18 PM 4/18/00 -0700, Bob Sciamanda wrote:
> > > It is not necessary to place this burden on Kirchhof's loop law.  It is
> > > valid even for non ideal capacitors and inductors;  eg, it even works for
> > > an open circuit - a highly fringing capacitor situation.

2) At 08:22 AM 4/19/00 -0400, Bob Sciamanda also wrote:
> Stating K's current law in the familiar form: "In steady state, the net
> current into any point is zero",  this is simply a statement of charge
> conservation and applies even to volume current distributions.  It is
> inapplicable only during the transient startup when (mostly) surface charge
> distributions are being established to drive the steady state current.

If "steady state" means DC, then K's law has nothing to say about
capacitors of any kind, or about fringing fields, and is not very useful.

If "steady state" includes "steady" AC signals, then statement 2 is false
in context.  Because of the fringing fields, there is a nonzero AC current
into the node which Bob calls an "open circuit".  The real physics violates
Kirchhoff's assumptions.

I renew the assertion that as applied to ordinary circuits, Kirchhoff's
laws are tantamount to assuming that circuit elements are black boxes, and
that there are no significant electric fields outside of "capacitor" black
boxes, and no significant magnetic fields outside of "inductor or
transformer" black boxes.