Magnetomotive force

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In physics, the magnetomotive force (abbreviated mmf or MMF, symbol ${\displaystyle {\mathcal {F}}}$) is a quantity appearing in the equation for the

$${\displaystyle {\mathcal {F}}=\Phi {\mathcal {R}},}$$

${\displaystyle {\mathcal {R}}}$

1. ${\displaystyle {\mathcal {F}}=NI}$
   where N is the number of turns in a coil and I is the electric current through the coil.
2. ${\displaystyle {\mathcal {F}}=\Phi {\mathcal {R}}}$
   where Φ is the magnetic flux and ${\displaystyle {\mathcal {R}}}$ is the magnetic reluctance
3. ${\displaystyle {\mathcal {F}}=HL}$
   where H is the magnetizing force (the strength of the magnetizing field) and L is the mean length of a solenoid or the circumference of a toroid.

Units

The

Ohm's law for magnetic circuits is sometimes referred to as Hopkinson's law rather than Rowland's law as some authors attribute the law to John Hopkinson instead of Rowland.^[6] According to a review of magnetic circuit analysis methods this is an incorrect attribution originating from an 1885 paper by Hopkinson.^[7] Furthermore, Hopkinson actually cites Rowland's 1873 paper in this work.^[8]

References

Bibliography

Cited sources

• Hon, Giora; Goldstein, Bernard R, "Symmetry and asymmetry in electrodynamics from Rowland to Einstein", Studies in History and Philosophy of Modern Physics, vol. 37, iss. 4, pp. 635–660, Elsevier December 2006.
• Hopkinson, John, "Magnetisation of iron", Philosophical Transactions of the Royal Society, vol. 176, pp. 455–469, 1885.
• Lambert, Mathieu; Mahseredjian, Jean; Martínez-Duró, Manuel; Sirois, Frédéric, "Magnetic circuits within electric circuits: critical review of existing methods and new mutator implementations", IEEE Transactions on Power Delivery, vol. 30, iss. 6, pp. 2427–2434, December 2015.
• Newell, David B.; Tiesinga, Eite, eds. (2019). NIST Special Publication 330: The International System of Units (SI) (Standards publication) (2019 ed.).
  doi:10.6028/NIST.SP.330-2019
  .
• Rowland, Henry A, "On magnetic permeability and the maximum magnetism of iron, steel, and nickel", Philosophical Magazine, series 4, vol. 46, no. 304, pp. 140–159, August 1873.
• Rowland, Henry A, "On the general equations of electro-magnetic action, with application to a new theory of magnetic attractions, and to the theory of the magnetic rotation of the plane of polarization of light" (part 2), American Journal of Mathematics, vol. 3, nos. 1–2, pp. 89–113, March 1880.
• Schmidt, Robert Munnig; Schitter, Georg, "Electromechanical actuators", ch. 5 in Schmidt, Robert Munnig; Schitter, Georg; Rankers, Adrian; van Eijk, Jan, The Design of High Performance Mechatronics, IOS Press, 2014
  ISBN 1614993688
  .
• ISBN 1108029213
  .
• Smith, R.J. (1966), Circuits, Devices and Systems, Chapter 15, Wiley International Edition, New York. Library of Congress Catalog Card No. 66-17612
• Waygood, Adrian, An Introduction to Electrical Science, Routledge, 2013
  ISBN 1135071136
  .

• The Penguin Dictionary of Physics, 1977,
  ISBN 0-14-051071-0
• A Textbook of Electrical Technology, 2008,
  ISBN 81-219-2440-5