Wirt Atmar <[log in to unmask]> wrote:

.......<snip>

>And Ted Ashton is also correct. As the frequency of an AC current is
>increased, it has a increased tendency to flow more and more on the surface
>of a wire (not necessarily a person). The phenomenon is called the "skin
>effect" and it is due to the fact that there is a "freer" gas of electrons
>near the surface of a wire (or any metal) than there is near its center.

No, the skin effect is a phenomenon that is forecast by Maxwell's equations
and predates any kind of electron theory.  It is caused by an interaction
between the magnetic and electric fields that "pushes" the current to the
outside of the conductor.  The skin depth is inversely proportional to the
square root of magnetic permeability (as well as conductivity and
frequency) and that leads to the interesting fact that it is significant at
much lower frequencies in magnetic materials such as iron than in
non-magnetic materials such as copper.

John D. Alleyn-Day
Alleyn-Day International
408-286-6421   408-286-6474 (Fax)
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