Don Stauffer wrote:
Maybe I should have said, copper, like MOST materials, has a resistivity
which is temperature dependent. Better?
Well, it appeared that you were specifically addressing this question:
"Why does the resistance [of the op's COPPER wire] go down when it gets hot?"
Saying that copper's resistance is temperature dependent still does not
answer the question, since the known temperature dependence (for
copper) is in the opposite direction to what the op measured. That is
what the question is all about: why is the measurement contrary to what
is known about copper?
But perhaps I'm mistaken and you weren't trying to address the above
question at all, just interjecting some general knowledge for our
benefit.
Mark