"Peter L. Peres" <plp@ACTCOM.CO.IL> wrote:
> On Fri, 26 Jul 2002, Wouter van Ooijen wrote:
> > A related 'trick' question: take a wire cube, each wire has a resistance
> > of 1 ohm. Put a 1 Volt battery on the two diagonally opposite points on
> > one side. How much current does the battery supply? The trick is of
> > course that some wires carry zero current.
>
> I beg to differ. There are no wires that bear zero current in a cube as
> you describe (hint: the number of edges the current has to traverse is
> always uneven - equal to three).

Check again. Remember, he specified diagonally across one face of the
cube. There are exactly two wires that carry no current.

If you apply the battery along a major diagonal, you need a different
"trick" to solve the problem, because in that case, all wires are
indeed carrying current.

-- Dave Tweed

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