Article ID: CBB001320909

Faraday's First Dynamo: A Retrospective (2013)


In the early 1830s, Michael Faraday performed his seminal experimental research on electromagnetic induction, in which he created the first electric dynamo---a machine for continuously converting rotational mechanical energy into electrical energy. His machine was a conducting disc, rotating between the poles of a permanent magnet, with the voltage/current obtained from brushes contacting the disc. In his first dynamo, the magnetic field was asymmetric with respect to the axis of the disc. This is to be contrasted with some of his later symmetric designs, which are the ones almost invariably discussed in textbooks on electromagnetism. In this paper, a theoretical analysis is developed for Faraday's first dynamo. From this analysis, the eddy currents in the disc and the open-circuit voltage for arbitrary positioning of the brushes are determined. The approximate analysis is verified by comparing theoretical results with measurements made on an experimental recreation of the dynamo. Quantitative results from the analysis are used to elucidate Faraday's qualitative observations, from which he learned so much about electromagnetic induction. For the asymmetric design, the eddy currents in the disc dissipate energy that makes the dynamo inefficient, prohibiting its use as a practical generator of electric power. Faraday's experiments with his first dynamo provided valuable insight into electromagnetic induction, and this insight was quickly used by others to design practical generators.

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Authors & Contributors
Faraday, Michael
Fisher, Howard J.
Wang, Luoyin
Hu, Hua-kai
Steinle, Friedrich
Cobb, Aaron D.
Ziran Kexueshi Yanjiu (Studies in the History of Natural Sciences)
Annals of Science: The History of Science and Technology
Nei Menggu Shifan Daxue Xuebao (Ziran Kexue Ban)
Studies in History and Philosophy of Science
Science and Education
Sudhoffs Archiv: Zeitschrift fuer Wissenschaftsgeschichte
Green Lion Press
Prometheus Books
New York University
Pavia University Press
Electricity; magnetism
Experiments and experimentation
Science and technology, relationships
Faraday, Michael
Maxwell, James Clerk
Ampère, André Marie
Wollaston, William Hyde
Whewell, William
Mill, John Stuart
Time Periods
19th century
20th century
Qing dynasty (China, 1644-1912)
17th century
18th century
Great Britain
United Kingdom

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