Re: TDC bulbs

[P3D Bob Wier <wier@xxxxxxxxxxxxxxx>]

At 7:33 AM 10/20/96, P3D Harry Poster wrote:

>   If I remember my electronics (a drop out from EE school)...AC current
> travels on the surface of a wire, as opposed to DC which travels throughout.
> If the wire shrinks (through evaporation), then the surface area is
> considerably smaller, and the AC current would be severly restricted. 

This is true, but the effect increases with frequency - at household
AC freqs, the effect is very small (actually, the wire diameter has to
approach some significant sub-multiple of the wavelength for it to come
into play). As you get up into the microwave frequenceies, it becomes
so significant that there is little point in actually putting metal
in the center since none of the electrons are travelling there. Thus
at radar (and above) freqs, you frequently see wireing which is more like
copper tubing that actual wires - a common example of this is the waveguide
which is seen for the pickup on satellite tv systems. This is known as
the "skin effect".

--de WB5KXH

   ====== wier@xxxxxxxxxxxxxxx ======
  Sunday, October 20, 1996 12:40 PM
   keeper of the Photo-3d, Motorola
 MC68HC11, Overland-Trails, LDS State
Research Outline Guides and other stuff
   



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