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On 2016, Mar 04, , at 13:30, Todd Pedlar <pedlto01@luther.edu> wrote:nice
I had a pretty good experience a couple weeks ago using regular 0.7 and
0.5mm HB mechanical pencil leads (actually it's great if you can also get
0.9 and 1.3 from the same company). Simply studying potential drop vs.
current for various lengths and for the different diameters enables a
verification of the relation between resistance, resistivity, length, andstudents
cross-section. Equipment used: DC power supply, banana cables w/aligator
clip ends, micrometer for length and diameter measurements, DVM. Really
quite straightforward to vary the length of the 'resistor' and my
did V vs. I plots for 8-10 lengths each, and for all four lead sizes.
Really nice and reproducible results.
TKP
I thought the point of using graphite pencil lead was their negative
resistance. Can one simply Joule heat it and find the R using I and EMF
while heating? the wood case acts as an insulator.
bc notes some leads show diamagnetism also.
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