On Wed, 17 Mar 2010 13:08:56 -0400, "Michael A. Terrell"
wrote:


John Larkin wrote:

On Tue, 16 Mar 2010 18:38:48 -0700, Archimedes' Lever
wrote:

On Tue, 16 Mar 2010 17:16:30 -0700, John Larkin
wrote:


You're an expert on this sort of thing, so estimate the resistance
before it was stretched, and how much it changed.

John


I question the efficacy of both sets of measurements.

You, saying that "you measured" something doesn't give one any warm,
fuzzy feelings upon contemplating the declared "observed results".

Why didn't you just say "I don't know how to do that"?

John


I wonder if anyone ever explained to dimbulb that copper wire is made
by drawing it through dies to reduce the diameter?

That work-hardens it, which makes it stiff and increases resistance.
It's usually annealed afterwards for electrical applications. If it's
not annealed, it's called "hard-drawn" copper, and the resistivity is
about 4% more than annealed. The breaking tension of the hard stuff is
about 50% higher than for the annealed.

We anneal our manganin shunts to get the TCs and drift under control,
after all the work-hardening of rolling out the metal and forming the
shapes.

I'm sure Dimmie can add details. He knows all about this stuff.

John