At DC the entire volume of the conductor is carrying current, not
just the surface.
The DC resistance of a conductor is:
R = [bulk resistivity] x [length] / [cross sectional area]
In the above area is independent of geometry. It works for round,
square, triangular, etc.
If current only flowed on the surface the above equation would have
the wire circumference in it instead of area.

For AC skin depth is a factor as others have already pointed out.
Changing the geometry of the conductor, from a rod to a sheet, is
one remedy for this. Litz wire is another and it is good for up to
about 1MHz IIRC.

Art


"Tom Watson" wrote in message
...
I had a conversation with a friend of mine today who has a masters in
electrical engineering.

This degree was conferred by the same school that I went to
(Villanova) about a hundred years ago, so I must inherently trust him.

Yet...

The question that I asked him, which I thought to be simple enough,
was - do the electrons travel down the circumference of the wire, or
do they travel through the core of the wire?

He told me that that is an unknown.

This was very surprising to me as I thought that it would be easily
tested.

Could we not create a wire of a core of inert material and coat it
with a conductor and measure the difference between a wire of the pure
element and that of the coated variety?

This seemed to be not within his reckoning.

The reason that it is important, to me, is that, if the electrons only
travel on the circumference, that circumference may be folded into a
smaller section than that described by the original, and wires would
not have to be so thick.

Would y'all please try to help me out of this conundrum?

Is my friend a poseur?





Regards,

Tom Watson

tjwatson1ATcomcastDOTnet (real email)

http://home.comcast.net/~tjwatson1/