Re: Is toroid a Faraday cage?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Jolyon,
           I think there may be the odd misconception here:

On 11 Jun 2002, at 17:59, Tesla list wrote:

> Original poster: "Jolyon Vater Cox by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
> 
> 
> Apart from role as a capacitor, does the toroid of a TC work along the
> principle of a Faraday cage or Faraday s Ice Pail or -similar to the dome
on a
> Van der Graaf generator- in that the secondary is connected to the inner
> surface where there is no net charge -all charge being collected on the
> exterior?

There has to be charge on the interior. If all electric charge 
resided on the exterior, there would be a nett voltage across the 
thickness of the metal which would be accompanied by a heavy current 
flow. There is no *nett electric field* present in the interior which 
is not the same thing.

> Also if the inner wall of a Faraday cage has infinite electrical
"suction" ie.
> it can never become charged no matter how much electricity is supplied to it,


Assuming an ungrounded cage, the above statement implies that one can 
effortlessly charge the exterior of the cage up to an infinite 
voltage which can't be true. Work has to be done to get the charge 
onto the cage, no matter which part of it is connected to the source.

> is the only difficulty in getting charge into the cage due to the 
repulsion of
> the electric field on the outside?

Yes. I've seen a highly charged Van de Graaf machine which uses a 
rubber belt actually creating sparks back down the belt due to the 
repulsion at the opening.
 
Malcolm