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Old 03-11-2019, 01:59 AM
bistander bistander is offline
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Princeton, homopolar and torque

From a quick search I do not find a lot of literature from Princeton on the subject but several I was able to view did in fact mention back torque of the homopolar generator. Here's one.

Published Online: 22 December 2014
Accepted: August 2014
Energy conservation and Poynting's theorem in the homopolar generator
American Journal of Physics 83, 72 (2015);
Christopher F. Chybaa)
Department of Astrophysical Sciences and Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, New Jersey 08544
Kevin P. Handb)
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
Paul J. Thomasc)
Department of Physics and Astronomy, University of Wisconsin, Eau Claire, Wisconsin 54702
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Most familiar applications of Poynting's theorem concern stationary circuits or circuit elements. Here, we apply Poynting's theorem to the homopolar generator, a conductor moving in a background magnetic field. We show that the electrical power produced by the homopolar generator equals the power lost from the deceleration of the rotating Faraday disk due to magnetic braking and review the way that magnetic braking arises within Poynting's theorem.
Highlighted passage (which I did) in the abstract confirms generator torque.

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