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Re: Capacitor charge, were is it?



>Message-ID: <199611050526.WAA20563-at-poodle.pupman-dot-com>
>Date: Mon, 4 Nov 1996 22:26:13 -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-comMon Nov  4 21:54:44 1996
>Date: Mon, 04 Nov 1996 15:38:59 -0800
>From: Richard Hull <hullr-at-whitlock-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: Capacitor charge, were is it?

  [ snip ]

>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.

   Whew!  I am glad we agree on that.


>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.

   Richard, I believe this is actually due to ions in the air
   currents.  If you trade a neutral molecule of nitrogen for a
   neutral molecule of nitrogen then there is no movement of charge at
   all.  (However, energy can be stored in the air molecule without
   its being ionized.)  If the electron is on the air molecule, then
   we have, by definition, an ion, do we not?  And ions drift in an
   electric field and deliver their charge to the other side.


>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! 

   What you have described here is not unlike the Van-de-Graaff
   accelerator, you merely draw a bit of parallel to the moving belt
   which carries the charge.  And I agree that the charge between the
   plates that you describe moves away - IN THIS CASE.  But you are
   dealing with a solid and not a gas.


>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.

   Yes, I know.  But what you say of solids DOES NOT apply to gasses!
   Why should it?  You actually don't have the grounds, I believe, to
   make this parallel.


>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.  

   The dosimeter has an 'air-lock' as it were where a pin goes through
   an insulated bellows to contact the inner pin.  These bellows are a
   little springy and are NOT normally in contact with the inner pin.
   During charging the outer pin connects to the charging voltage and
   makes contact to the inner pin.  After charging the outer pin
   disconnects from the inner pin, but the outer pin is still not
   grounded and so retains a small charge.  When we discharge this
   outer pin with a paper clip, there is a tiny change in the voltage
   on the inner pin strictly due to the capacitive-voltage-divider
   effect, and the dosimeter's fiber moves upscale slightly.  This
   "zero drift" would occur anyway as the outer pin gradually
   discharges due to air ions or leakage currents (in surface dirt).
   So it's better to get it all over with at the start than to get a
   false-positive dose reading for somebody.  So we charge the
   dosimeter to minus 3 millirem and then discharge the outer pin and
   the dosimeter reads zero.


>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.

   Agreed.


>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.

   The UV light in Einstein's case knocked electrons off the METAL by
   photoemission.  That's the discovery he explained.  But he had to
   introduce the idea that the shorted wavelengths of light had more
   energy per 'particle'.


>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


   Richard, the only way that the admission of pure non-ionized air
   would discharge (or, take the charge away from) such a capacitor is
   if the air molecules inside the dosimeter actually had literally
   the charge (not just the energy) distributed *among them* and the
   incoming air just flushed or rinsed them out.  I believe this is
   exactly what you are describing.

   So, taking this one step further, are you saying that inside the
   dosimeter and the electroscope that the electrons (in the case of a
   negative charge) are distributed throughout the gas itself by being
   attached to the gas molecules themselves? and that some are landing
   on the inner surface of the glass, among other places?  While this
   might be conceivable for the electroscope, this CANNOT be the case
   in the dosimeter since the air chamber across which the voltage
   exists has conductive walls in order for the **trapped** ion pairs
   created by ionizing radiation actually to discharge the capacitor,
   with the positive ions drifting one way and taking electrons from
   the negative wall, and with the negative ions drifting the other
   way and giving up electrons to the positive wall.  Thus the
   charge*difference between the walls is reduced and the fiber moves
   because the force it feels is less.  If the charge were actually
   distributed on the gas molecules in the first place, then the
   capacitor would just never work - it would just be a resistor with
   the gas molecules ferrying the electrons from one wall to the
   other.  However, this does NOT happen.  We do know that the
   difference in charge between the walls (or, across the whole air
   gap) is indeed constant in event of no ionizing radiation because
   the needle doesn't move.  So, clearly, I think we can say where the
   really electrons are and where they are not.  Do you not agree?  Or
   at least we can say where they are NOT going.  They cannot be
   drifting around in the gas, otherwise the chamber would just
   discharge itself.   That would be like trying to keep change in
   your pocket whilst walking around with a hole in it.  The
   'hourglass' effect, as it were.

   Not only that, for the gold leaves to have a force **against each
   other** that is where the charge has to be in order for the force
   to be there.  This is *exactly* like the space-charge problem with
   electrons in a vacuum - they repel each other and accelerate away
   from each other unless constrained, in this case they are confined to
   the vicinity of the gold by the fact that the air doesn't conduct
   electrons away.  So here we have another proof of where the charge
   is.  Gold foils in a vacuum would do exactly the same thing.

   Notice that I didn't really say where the 'energy' is.  Like a 
   weight on a spring, we know where the weight is, but the energy is
   stored **throughout** the spring.  Thus it is with the air
   dielectric in a dosimeter or electroscope.  The air molecules are
   electrically  'sprung', having their electron orbits distorted but
   not disrupted.  Shoving another spring under the weight takes no net
   energy if we recover the energy that the outgoing spring gives up. 
   So it is with letting in perfectly dry clean non-ionized air into
   an air capacitor - it should NOT disturb the charge on the
   capacitor, as I see it.
 
   So this would be a good test of my theory, Richard.  Has anybody
   actually ever done this experiment *correctly*?  Fresh air is
   totally useless here, as it is loaded with ions and cannot be used
   for this experiment.  As a matter of fact, as warm-blooded
   oxygen-breathing mammals, we all have built into our cells an
   O2-minus ion transport system.  This is one reason why fresh air
   (and air from Tesla Coils) kills bugs (they lack this
   bio-mechanism) and oxidizes odours.  Pulling off the plug on an
   electroscope is anything but a fair test, IMHO.

   So am I totally out to lunch, or what? 


 Fred W. Bach ,    Operations Group        | Internet: music-at-triumf.ca
 TRIUMF (TRI-University Meson Facility)    | Voice:  604-222-1047 loc 6327/7333
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 University of British Columbia, Vancouver, B.C., CANADA   V6T 2A3
 "Accuracy is important. Details can mean the difference between life & death."
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 They do NOT necessarily reflect the views of my employer or fellow workers.