Re: Conserving Q/Faraday

[Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>]

Bob Sciamanda asks:
> If you disassemble the discharged capacitor inside the Faraday cup
> (with attached electrometer) and remove the plates one at a time,
> when does the electrometer show a non-zero reading?

We did not do this. We measured the net Q of the whole thing without
separating pieces. And we did this with the dielectric slab coated by
layers of graphite paint, not surrounded by Al plates which can be
separated.

> > WE NEED ADVICE
> > . . . . .
> > 3) HERE IS MY QUESTION. Suppose that a net charge is really
> > present in the dielectric slab of a capacitor connected to HV. How
> > can this net charge possibly be revealed? A naive approach was
> > to disconnect C from the power supply, discharge it and stick it
> > (without dissecting) into the Faraday cup. By doing this we always
> > find that the net Q is zero. But this refers to the sum of charges
> > on three objects (the dielectric slab and two electrodes), not to
> > the Q in the dielectric slab alone. The discharged electrodes are
> > not necessary neutral, they may have +  and - charges induced by
> > the layers of the remaining bound charges in the dielectric. If so
> > then the net Q in the electrodes compensates the net Q in the
> > dielectric.