Physics

The Columbia Encyclopedia, 6th ed. A Dictionary of Earth Sciences Further reading

Lenz's law

The Columbia Encyclopedia, 6th ed. | 2011 | Copyright

Lenz's law physical law, discovered by the German scientist H. F. E. Lenz in 1834, that states that the electromotive force (emf) induced in a conductor moving perpendicular to a magnetic field tends to oppose that motion. When an electric motor is in operation, the armature is turning in a magnetic field, and an emf is thus induced in it. Lenz's law requires that this emf, called back emf or counter emf, oppose the motion of the armature and also the original emf, causing the motor to operate. As a result, the speed of the motor changes in such a way that the energy supplied by the original voltage source less the energy required to overcome the back emf is always exactly equal to the sum of the energy used to drive the mechanism to which the motor is attached and the energy lost as heat within the motor. Lenz's law may thus be seen as a consequence of the law of conservation of energy (see conservation laws , in physics).

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Lenz's law

A Dictionary of Earth Sciences | 1999 | | Copyright

Lenz's law When a magnetic field and an electrical circuit are moved in relation to one another, an electric current is induced in the circuit such that it forms a magnetic field opposing the motion.

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AILSA ALLABY and MICHAEL ALLABY. "Lenz's law." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 26 May. 2012 <http://www.encyclopedia.com>.

AILSA ALLABY and MICHAEL ALLABY. "Lenz's law." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 26, 2012). http://www.encyclopedia.com/doc/1O13-Lenzslaw.html

AILSA ALLABY and MICHAEL ALLABY. "Lenz's law." A Dictionary of Earth Sciences. 1999. Retrieved May 26, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-Lenzslaw.html

Learn more about citation styles