Re: Capacitor charge, were is it?

To: tesla-at-pupman-dot-com
Subject: Re: Capacitor charge, were is it?
From: Dan Gowin <gowin-at-epic-1.nwscc.sea06.navy.mil>
Date: Mon, 28 Oct 1996 09:52:27 -0500
Tesla List wrote:
> 
> >From ed-at-alumni.caltech.eduSat Oct 26 23:37:23 1996
> Date: Sat, 26 Oct 1996 10:04:22 -0700 (PDT)
> From: "Edward V. Phillips" <ed-at-alumni.caltech.edu>
> To: tesla-at-pupman-dot-com
> Subject: Re: Capacitor charge, were is it?
> 
> "There is a classic problem in which two identical capacitors are connected
> with a switch. Before the switch is thrown one capacitor has a certain
> voltage, the other none. If we give numbers, let's say C=1uF and V=1000V on
> the first capacitor. The energy is (cv^2)/2 = 0.5 joules. Now after the
> switch is closed both capacitors will have v/2 = 500V across them. This can
> actually be done. But now the energy in the system is half the original
> value.
> (1uf*500^2)/2 = 0.125 joules/cap times two caps = 0.250 joules. Were is the
> other half?"
>         The rest of the energy was dissipated in resistive losses while
> the current flowed.  If there were no resistance in the circuit there
> would be an undamped train of oscillations due to the inductance of
> the interconnecting leads.  No laws of nature violated.
> "The classic things I've been taught have me confused with the actual
> workings of nature. If two charged plates (air dielectric) have a certain
> charge Q and then a dielectric is inserted between them with a K>1, the
> voltage should decrease since the charge hasn't changed but the capacitance
> has increased."
>         An even simpler experiment is to consider a capacitor (say
> two spheres) which is charged to some voltage.  If you separate
> the plates (spheres, etc) the voltage difference between them rises,
> while if you bring them closer together the voltage difference is
> reduced.  Conservation of charge holds.  People have built high-
> voltage electrostatic generators in which a rotating variable
> capacitor was charged in the high-capacitance state, and then
> discharged as the capacitance was reduced and the voltage raised.
> Ed Phillips

All,
	If I remember my history correctly, Benjamin Franklin used an
electro static device that relied on the principal of charged plates.
This
device consisted of a jar with a cork lid, and a copper hook protruded
through the lid with a ball attached to the external end. On the hook
end
inside the jar, a peice of copper foil was folded in half and draped
over
the hook. The idea being, if a charge was placed on the foil, the two
halves would repell each other and the foil would open up. 

	The above, It would seam, enforce the idea that in a capacitor the
charges (i.e.: Electrons and holes) are indeed contained with the
metallic
plates. The old world knowledge of our grandfathers still holds true
today.
Ed Phillips and all of the others that have pointed this out are
correct.

D. Gowin