This is an unfinished document that is part of another project - the start of some notes on how to perform electrical measurements in general, and specifically on samples of real, live materials. After our next meeting, it might be of interest.
Basically, the more interesting part at the end shows you how to calculate the resistivity (or conductivity) of a conducting material from experimental data, the so-called 'four point probe' technique. Moreover, you can figure it out for conductors of various interesting shapes, like thin films, using very general symmetry-related arguments. We'll cover the necessary background in Friday's recitation.
If you're studying or planning to study anything materials- or device-related, you will see the four-point probe technique again. It is not hugely difficult, but not commonly covered in any depth, and usually just taken on faith. So, when you do see the four-point probe expressions again, you can smile and know that they are not, in fact, magic.
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