Re: Capacitor problem

[LUDWIK KOWALSKI <kowalskil@alpha.montclair.edu>]

      The main question of this message is item #3, at the end.

1)   On Mon, 31 Mar 1997 Roger Pruitt wrote:

> .. we were instructed to not use the term "condenser" with the explanation 
> that it doesn't condense anything."

A device which takes 10 times more Q, from a source of given dV, has more
coulmbs per volts (farads). In that sens it does condense something. The 
term capacitor, as pointed out earlier, can lead to misconceptions.

2) A little later Alex Burr wrote:

> I have observed the EM energy radiated when a capacitor is discharged. 
> Place the capacitors near a radio receiver and discharge the set up. You 
> will hear the radiation.

Naturally; the current flows from plate to plate through a wire and you
have an LC circuit. And if the wire has low R the radiative losses are
likely to dominate. But we were NOT talking about the flow of electrons
from one plate to another. We were talking about two capacitors, one 
charged and one not charged. The original question was - what happens to 
the missing energy after C1 and C2 are connected ?

Note that the charges were separated in the initial state and they are 
separated in the final state. Only redistributions of +Q and -Q are taking 
place when parallel plates are alowed to touch each other. The redistribution 
currents are confined to thin layes; this is due to the mutual attraction of 
dislike charges. Presumably the plates are very close to each other (the 
usual "no fringe effect" configuration).

I suspect that high R may prevent oscillations (ovedamped situation) and 
most of the missing energy will become heat rather than waves.

3) Yesterday I said that this may be easy to verify with a calorimeter.
The super-caps should be disconnected and discharged quickly before dropping 
them into water. But you, Alex, mentioned, long time ago, that supercaps have 
internal resistance. That will create a problem. How can one be sure that the 
heat was not produced during the discharging? The effective specific heat
of two super-caps must be measured somehow before the experiment. Please 
advice me; I tentatively plan to verify the prediction.