The Physics Teacher, Vol. 42, No. 9, p. 553, , December 2004
©2004 American Association of Physics Teachers. All rights reserved.
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The Simplest Motor?

Christopher Chiaverina

Column Editor

4111 Connecticut Trail, Crystal Lake, IL 60012
fizzforfun@aol.com

Contents

This motor consists of four simple parts: a cylindrical "neodymium" (NdFeB) magnet,1 a steel nail, a D-cell battery, and a short piece of (nonferromagnetic) wire. It's amazingly easy to put together and runs beautifully every time. Just assemble the pieces as shown in Fig. 1 (the magnet sticks to the head of the nail and the tip of the magnetized nail is attracted to the ferromagnetic bottom of the battery). Now, hold one end of the wire to the top of the battery and touch the other end to the side of the magnet. A current flows through (and/or along the surface of) the magnet as shown in Fig. 2. The charge carriers moving in a magnetic field experience a force whose direction is given by the right-hand rule. This direction defines the sense of rotation of the motor. The device is called a homopolar motor.2

Figure 1. Figure 2.

Column Editor's Note: This "Gem" was inspired by a demonstration described in a booklet written by "The Stray Cats," a group of Japanese physics teachers.

REFERENCES

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References

  1. Available from Arbor Scientific (http://www.arborsi.com), Cat. No. P8–1123, $15.00/pair. first citation in article
  2. See, for example, Jorge Guala-Valverde et al., "The homopolar motor: A true relativistic engine," Am. J. Phys. 70 (10), 1052–1055 (Oct. 2002) and references therein. [ISI] first citation in article

CITING ARTICLES

This list contains links to other online articles that cite the article currently being viewed.
  1. Motional Mechanisms of Homopolar Motors & Rollers
    H. K. Wong, Phys. Teach. 47, 463 (2009)
  2. Levitated Homopolar Motor
    H. K. Wong, Phys. Teach. 47, 124 (2009)
  3. The Homopolar Motor and Its Evolution
    Norihiro Sugimoto et al., Phys. Teach. 44, 313 (2006)
  4. Force on a Current-Carrying Wire
    Seán Stewart, Phys. Teach. 44, 245 (2006)
  5. The Simplest Generator from the Simplest Motor?
    Robert Beck Clark, Phys. Teach. 44, 121 (2006)

FIGURES

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Fig. 1. The simplest motor? First citation in article

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Fig. 2. Schematic diagram. First citation in article

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