Challenging Faraday's Flux Law and the Lorentz Force

by Some Simple New Measurements on a Faraday Disk

  • Hermann Haertel University Kiel


In the light of the presented measurements on a Faraday generator the well-known theories
concerning Unipolar Induction and the Faraday paradox seem to be problematic. On the other
hand, all results obtained here and all other processes described as paradox in connection with
the Faraday generator can be explained without contradiction on the basis of the theory of Wilhelm Weber.


Assis, A. K. T. and Peixoto, F. M. (1992). On the Velocity in the Lorentz Force law, 
The Physics Teacher, Vol. 30, pp. 480-483.
Assis, A. K. T. and Thober, D. S. (1994). Unipolar Induction and Weber's Electrodynamics, in Frontiers of Fundamental Physics, M. Barone and F. Selleri (eds.), Plenum Press, New York, pp. 409-414.
Assis, A. K. T. (1994). Weber's Electrodynamics (Kluwer, Dordrecht). Nowadays this book is available through Springer.
Assis, A. K. (1990). Deriving Ampère’s law from Weber’s law. Hadronic Journal, Volume 13, 441-451
Chen, K., X.-J. Li and Y.-X. Hui (2017). An Experimental Study on Unipolar Induction, Acta Physica Polonica A, Vol. 131, pp. 271-274.
Einstein, A. (1952). On the electrodynamics of moving bodies. In A. Einstein, H. A. Lorentz, H. Weyl and H. Minkowski, The Principle of Relativity, pp. 35–65, New York, Dover.
Faraday, M. (1832). Philosophical Transactions of the Royal Society of London, Vol. 122, pp. 163-194.
Feynman, R. P.; Leighton, R. B. and Sands, M. (1969). The Feynman Lectures on Physics, Electromagnetism I, Addison-Westley, 17/3-4.
Galili, I. and Kaplan, D. (1997). Changing approach to teaching electromagnetism in a con-ceptually oriented introductory physics course, Am. J. Phys. 65, 657.
Härtel, H. (2018). Electromagnetic Induction: An Alternative for Teaching and Understanding. European Journal of Physics Education, 9, 2, p. 1-13.
Guala-Valverdea, J. Mazzoni, P. and Achilles, R. (2002). The homopolar motor: A true rela-tivistic engine, Am. J. Phys. 70, 1052.
Kelly, A. G. (1998). Faraday's Final Riddle: Does the Field Rotate with a Magnet? Monographs 5 & 6 of the Institution of Engineers of Ireland.
Leus, V. and Taylor, St. (2011). On the motion of the field of a permanent magnet, Eur. J. Phys. 32, 1179.
Munley, F. (2004). Challenges to Faraday’s flux rule, American Journal of Physics, 72, 1478.
Scanlon, P. J.; Henriksen, R. N. and Allen, J. R. (1969). Approaches to Electromagnetic In-duction, The American Journal of Physics, Volume 37, 698.
Weber. W. (1846). Elektrodynamische Maassbestimmungen — Über ein allgemeines Grundgesetz der elektrischen Wirkung. Abhandlungen bei Begründung der Königl. Sächs. Gesellschaft der Wissenschaften am Tage der zweihundertjährigen Geburtstagfeier Leibnizen’s, herausgegeben von der Fürstl. Jablonowskischen Ge-sellschaft (Leipzig), pages 211–378, 1846. Reprinted in Wilhelm Weber’s Werke, Vol. 3, H. Weber (ed.), (Springer, Berlin, 1893), pp. 25-214. English translation: Deter-minations of electrodynamic measure - concerning a universal law of electrical action, translated by S. P. Johnson, edited by L. Hecht and A. K. T. Assis, 21st Century Science and Technology, posted in March 2007. Available at and
Weber, W. (1872). Electrodynamic measurements – sixth memoir, relating specially to the principle of the conservation of energy, Philosophical Magazine, Vol. 43, pp. 1-20 and 119-149
Zengel, Z. (2019). The history of the Faraday paradox of the unipolar generator, Eur. J. Phys. 40, 055202.
Zuza, K., De Cock, M., van Kampen, P., Bollen, L. and Guisasola, J. (2016). University students’ understanding of the electromotive force concept in the context of electro-magnetic induction. European Journal of Physics, 37(6): 065709.
How to Cite
HAERTEL, Hermann. Challenging Faraday's Flux Law and the Lorentz Force. European Journal of Physics Education, [S.l.], v. 12, n. 4, p. 26-37, nov. 2021. ISSN 1309-7202. Available at: <>. Date accessed: 22 sep. 2023. doi: