On Wed, 17 Sep 2008 17:20:56 -0700 (PDT), Art Unwin
wrote:

I know books say a lot of things but do they explain WHY current
cannot flow thru the center?

Sure they do. Look under "skin effect".
http://en.wikipedia.org/wiki/Skin_effect
The components of the fields generated by AC conduction tend to repell
each other, causing them to drift towards the points of maximum
seperation, which is the outside of the conductor.

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Jeff Liebermann
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