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Re: Capacitor charge, were is it?
Tesla List wrote:
>
> >From music-at-triumf.caSun Nov 3 22:42:47 1996
> Date: Sun, 03 Nov 1996 10:15:44 PST
> From: "Fred W. Bach, TRIUMF Operations" <music-at-triumf.ca>
> To: tesla-at-pupman-dot-com
> Cc: music-at-triumf.ca
> Subject: Re: Capacitor charge, were is it?
>
> >Message-ID: <199611020526.WAA07030-at-poodle.pupman-dot-com>
> >Date: Fri, 1 Nov 1996 22:26:19 -0700
> >From: Tesla List <tesla-at-poodle.pupman-dot-com>
> >To: Tesla-list-subscribers-at-poodle.pupman-dot-com
> >Subject: Re: Capacitor charge, were is it?
>
> >From hullr-at-whitlock-dot-comFri Nov 1 21:50:44 1996
> >Date: Fri, 01 Nov 1996 11:53:10 -0800
> >From: Richard Hull <hullr-at-whitlock-dot-com>
>
> >>
> >> I would think that if the charge were in the air, you could blow the air
> >> away, or simply move the electroscope, and the leaves would collapse. Is
> >> this the case?
> >>
> >> Steve Roys
> >
> >
> >Good boy Steve!!!
> >
> >It is always the space that is charged, but the molecules in the air
> >contribute to the alteration of same. You would have to blow away the
> >air inside the jar of the electroscope as well as outside. Remember, the
> >charge is separated at each end of the air/metal rod interface. To prove
> >this, and mix the air, just simply lift the stopper, rod, leaves, and all
> >out of the bottle. The leaves will collapse!!
> >
> >Richard Hull, TCBOR
>
> Are you telling us that mixing the *internal* air in air-dielectric
> capacitor discharges it? Then how do our pocket dosimeters work?
> This just cannot be true. They are little chambers with an
> extremely dry gas inside them. We charge our pocket dosimeters up
> to about 300 volts and they can stay charged forever unless exposed
> to ionizing radiation which produced ion-pairs in the gas. The
> internal gas can be circulated by any and all motions of the
> dosimeter. The dosimeter is exactly the same as the gold-leaf
> electroscope only we have a fiber instead of a leaf, and the
> dosimeter is optically read by the user. If the charge really were
> on the gas then mixing it would discharge the capacitor. But by
> years of experience it doesn't work that way as far as I can see.
>
> Has anyone ever put in a fan inside a sealed electroscope? That
> would be interesting!
>
>
> Do you think Einstein's research (leading to his Nobel Prize),
> which involved the discharging of capacitors by ultraviolet light,
> might be pertinent here?
>
> Incidentally, what you say about mixing the air in an air capactior
> thereby discharging it might be true at higher voltages than 300 volts.
>
> Fred W. Bach , Operations Group | Internet: music-at-triumf.ca
> TRIUMF (TRI-University Meson Facility) | Voice: 604-222-1047 loc 6327/7333
> 4004 WESBROOK MALL, UBC CAMPUS | FAX: 604-222-1074
> University of British Columbia, Vancouver, B.C., CANADA V6T 2A3
> "Accuracy is important. Details can mean the difference between life & death."
> These are my opinions, which should ONLY make you read, think, and question.
> They do NOT necessarily reflect the views of my employer or fellow workers.
Fred,
Mixing the air in the electroscope or a dosimeter will have zero effect
on the leaves. You misunderstood me. The air trapped inside the
dosimeter and the electrosope is a polarized and electrified dielectric!
Mixing it up inside the bottle or dosimeter has not effect. Mixing it
with the outside air will! The separated charge in the stable dielectric
in the bottle would no longer be stable. Remove the entire mechanism
from the electroscpe and charge it in free air. It will charge, but it
will discharge very rapidly due to air currents sweeping in and around
the metal/dielectric interface. To be of any value, we have to have a
stable dielectric medium to support the polarization and thus hold the
leaves apart.
We could look at it like a polyethylene capacitor with plates in a pipe
filled with molten polyethylene. If we charge the capacitor and remove
power then start pumping the polyethylene away to be replaced by a fresh
supply, the charge is gone! The new polyethylene didn't know a thing
about the charge which left with the old dielectric medium. The charge
was never-ever on the plates! It was contained within the space of the
dielectric. This is process is actually used to charge liquids in
industry.
So it is with the electroscope and the dosimeter. The dosimeter, after a
number of charge discharge cycles, will hold its charge almost
indefinitely due to the fact that only a tiny piece of metal is exposed
to outside air. This charge is held by the trapped dielectric air inside
the instrument. Only ionizing radiation can alter this state of affairs
by depolarizing the air within. It does nothing to the metal.
As to the last two questions, UV light discharges an air cap by ion
production just like radiation. Thereby, depolarizing the dielectric not
the metal.
Finally, electroscopes and dosimeters are charged to hundreds of volts to
searate their leaves. Thus air mixing with outside air would discharge
them. My 100mr dosimeter requires 500 volts to zero, and the gold leaf
electroscope I have requires at least 800 volts to spread the leaves out.
Richard Hull