Robert A. LaBudde wrote:
> Consider an infinite plane of a uniform resistivity material (e.g.,
> conductive foam).
>
> Take two points A and B a fixed distance apart in this plane:
>
> <^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^>
> < >
> < A B >
> < >
> <vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv>
>
> How, using techniques of electrical engineering, can the resistance in
> ohms be calculated between points A and B?

I remember working out exactly this case many years ago back in school.  The
resistance is infinite unless "points" A and B have a non-zero radius.

> Obviously it can be measured easily in practice by simply placing one
> ohmmeter probe at A and the other at B.

Not so obvious.  Try it and you'll see it has a lot to do with the contact
area at each probe tip.  If the material deforms easily, you will get very
different answers depending on how hard you press the probes into the
material.


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