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March 31, 20224:00 pm – 5:00 pm (CDT)

Voltaic Cells: The Good (Faraday), the Bad (Volta), and the Ugly (Galvani)

Speaker:

Wayne Saslow (Texas A&M University)

Host:

Rainer Fries

Location:

Address:

Mitchell Institute for Fundamental Physics & Astronomy

College Station, Texas 77843

Event Details

We all use batteries constantly, but the usual discussion in physics textbooks — where one would expect to learn about voltaic cells, which in parallel and/or series combination constitute batteries — leaves many unresolved questions: (1) no real discussion of emf and why small AAA cells have the same emf as much larger A cells; (2) no discussion of how chemistry produces the emf, and that there are two distinct electrodes; (3) the false impression that the emf occurs within the volume of the cell; (4) no discussion of chemical “charge” and energy storage; (5) the imaginary dotted box drawn around the voltage source and “internal” resistance; (6) no discussion of the differences between fast charge and discharge, and slow charge and discharge; (7) 100-1000x too large internal resistances for the typical car-starting battery. Eventually I resolved these questions to my satisfaction, and last year I published a related paper in the Physics Teacher (see title of talk).  In addition to resolving these questions, it also discusses: (A) the different definitions of cathode and anode used by battery-ists, chem-ists, and physic-ists; (B) the distinction between “charge” and “surface charge”; (C) Why Faraday is Good, Volta is Bad, and Galvani is downright Ugly. Because figures (including a fictional one of a young Feynman in a slowly-emptying bathtub) will mostly replace equations, I will try to finish early and then open up for questions from the audience. 

Video Recording

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