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Re: Capacitor charge, were is it?

On 10/28/96 22:25:33 you wrote:
>
>> >Subject: Re: Capacitor charge, were is it?
>
>> [snip to save Chip's eyes]
>> >>If this is true we could not have a capacitor with a charge that has no
>> >>dielectric (vacuum).
>> >
>> >Since a vacuum is a conductor (i.e vacuum tube), you cannot have a 
potential
>> >difference (charge) in a pure vacuum.  This concept is theoretical.
>> >
>> [ditto]
>>         Sorry,
>>                 But a vacuum is NOT a conductor. The conduction in a
>> vacuum tube is due to the electrons boiled off the cathode flowing
>> through free space toward the positive plate.  If you reverse the
>> applied voltage (plate more negative) then no current will flow.  This
>> is exactly how a vacuum rectifier tube works.  If the vacuum were
>> conducting, then the vacuum rectifier would conduct in both
>> directions.
>> 
>> In other devices, without a thermonic cathode, the electrons are
>> ejected/ripped out of the cathode whenever the electric field is
>> greater than the work function of the material. That is: when the
>> force on the electron from the electric field is greater than the
>> force holding it in the material.  This effect is called field
>> emission.
>> 
>>         Regards,
>> 
>>         jim
>
>
>Jim, 
>
>I am glad you caught this one, I was about to comment on it myself.  The 
>vacuum of space is the best insulator known.
>
>Richard Hull, TCBOR
>
>
  
I am afraid I must bore you with another comment to clarify my position and 
understanding.  If space is the best insulator known, rather than a 
conductor, then how is it that space conducts electomagnetic energy so well?  
In the classic sense of what a conductor is at DC, space is indeed an 
insulator (and very poor dielectric I might add).  But when it comes to the 
matter of passing electromagnetic energy, whether this energy is in the form 
of photons or electrons, the vacuum is a very good conductor indeed.

Electromagnetic energy from the sun is the primary source of energy for the 
planet and it propagates through essentially a vacuum (space).  Still seems 
like a pretty good conductor to me :>)

Phil Gantt

Phil Gantt (pgantt-at-ix-dot-netcom-dot-com)
http://www-dot-netcom-dot-com/~pgantt/intro.html