Physics reference

A place to keep track of reference material - any particularly useful books, articles, etc. should be listed here.
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Dan Tibbets
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Physics reference

Post by Dan Tibbets » Tue Jun 24, 2008 5:50 am

FYI, while I was searching for information on resistivity I came across this site. It covers various physics topics in a hypercard type format. I was unaware that copper wire's resistance decreased so much when very cold. Makes me wonder if superconducting materials are essential to make magnetic confinement schemes work.

http://hyperphysics.phy-astr.gsu.edu/hb ... html#ahph1


Dan Tibbets

John Futter
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Re: Physics reference

Post by John Futter » Tue Jun 24, 2008 6:42 am

Most conductors change resistance with temperature (constantan a notable exception).
Copper thermometers are very common in low temperature work. Copper is not a good candidate for use over 300 degrees celsius as it tends to oxidise rapidly( and if using a relay the insulation will limit you to what the insulation is rated to typically a max of 150 degrees celsius or less).

I have used relay coils for accurate temp sensors for years for ambient and below type temps.

you only need to know the resistance and temp at one point and it is linear over a large range.

much cheaper than Pt 100 sensors.

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