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Re: Flat conductors (was I need help).



Larry Woolf wrote:

I do a number of experiments with graphite lines on a piece of paper and
have looked at the lines using a scanning electron microscope. They are
certainly of non-uniform thickness, consisting of many touching flakes. I
agree with David that there is likely significant junction resistance
between carbon coated material, as well as between the metallic electrode
and the carbon material. So the measured resistance would be expected to be
much higher than expected from the carbon material resistivity, cross
sectional area, and length.
To complicate issues further, don't forget that graphites and carbons are
anisotropic, with conductivities much higher in the graphitic planes
compared to perpendicular to the planes.

Interesting. But all this should not prevent us from trying to
explain the observed patterns of equipotential lines quantitatively.
It differs from what was expected for a vary large sheet of paper.

1) Is it a "pure paper size" effect?
2) Is it a "pure static surface charges" effect?
3) Is it something else?
4) Are #1 and #2 unseparable?

My guess is that #4 is correct. Even an infinite sheet must have
surface charges to bend electric field lines in a flat conductor.
Ludwik Kowalski.