2012 BFY Abstract Detail Page
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||What carries the current in a metal?: A modern version of the Tolman-Stewart experiment
||The Tolman-Stewart experiment in 1916 was the first experiment to show that charge carriers inside a metal were electrons -- the same electrons discovered in J.J. Thomson's cathode rays. Their experiment is conceptually very simple: a coil of copper wire is spun at a high speed and then suddenly braked; the electrons continue to move in the coil until slowed by the resistance of the copper. From a measurement of the charge that flows in the coil, we can find the ratio of e/m. We report on a modern version of the Tolman-Stewart experiment and compare our results to results from a cathode ray tube (another undergraduate laboratory staple). This experiment can prove to students that the charge carriers in copper are electrons, and gives avenues for future expansions: finding the effective mass and sign of the charge carrier.
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Kelley D. Sullivan
953 Danby Rd.