Re: Expanding Space

From: George Dishman (george_at_briar.demon.co.uk)
Date: 03/04/05 

Date: Fri, 4 Mar 2005 16:40:38 -0000

"Sue..." <suzysewnshow@yahoo.com.au> wrote in message
news:1109889900.178170.70840@f14g2000cwb.googlegroups.com...
> George Dishman:
> "Skin effect" means that at high frequencies, the current
> flows on the surface, not in the bulk of the material,
> but that is different from the energy flow.
>
>
> At high frequencies the ohmic resistance becomes insiginificant.
> For wave guides and fiber optics infinite ohmic resistance
> works just fine.

Indeed, just a change of refractive index is all
that is needed.

> So long as the path has low I^2*R losses, the dielectric
> properties of the path carry the energy quite nicely.
>
> The Jefferies URLs put the Poynting vector into a little better
> perspective. Well worth the visit.

Yes, I like his approach but my point was fairly
simple. In a waveguide, the energy doesn't flow
along the metal of the guide, it is in the
enclosed volume which can be evacuated. The same
is true for a coax where the power flows in the
space between the outer surface of the inner and
the inner surface of the outer.

George

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