Re: Surface Charges and Feedback in Simple Circuits

[Brian Whatcott <inet@INTELLISYS.NET>]

At 03:45 PM 2/16/02, you wrote:
> Having read Preyer's preprint, I now conclude he is modelling an RC
> discharge but has chosen an RC decay time of several nanoseconds and
> propagation time (d/c) and decay time (pho*epsilon) of the order of
> picoseconds.   His simulations go only to about 150 picoseconds and so
> never approach a static equilibrium - a well defined, "slowly" decaying
> current is still flowing - the "intermediate state" which you correctly
> inferred (exponential decay).
>
> Bob Sciamanda (W3NLV)



If one wanted an intending engineer or physicist to get some realistic
even useful ideas about the  time progress of electrical effects in an
 LC circuit, I suggest he could demonstrate a very large lumped
 inductance of perhaps 1 Henry, connected to a large (initially charged)
 lumped  capacitance - say  1 Farad
by means of a lumped transmission line consisting of perhaps six sections
of series inductor pairs of 100 millihenry with five parallel capacitors of
100 millifarad.
This would slow the progress of the
traveling wave so that an oscilloscope (perhaps even a moving coil meter)
 could track its progress between cap and coil.
Then the student  could say some experimentally verifiable
things about temporal progression of potential in lumped circuits.

Brian Whatcott
  Altus OK                      Eureka!