2012 BFY Abstract Detail Page

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Abstract Title: What carries the current in a metal?: A modern version of the Tolman-Stewart experiment
Abstract: 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.
Abstract Type: Poster
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Author/Organizer Information

Primary Contact: Kelley D. Sullivan
Ithaca College
953 Danby Rd.
Ithaca, NY 14850