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Re: Capacitor charge, were is it?
>Date: Sat, 26 Oct 1996 20:29:05 -0700
>From: pgantt-at-ix-dot-netcom-dot-com
>To: tesla-at-poodle.pupman-dot-com
>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