Magnetic energy © Siemens Stiftung 2018 CC BY-SA 4.0 international

Magnetic energy

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Overview graphic:
Two manifestations of magnetic energy are compared: the magnetic energy of a current-bearing coil and that of an elementary magnet.

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2018-10-26
Magnetic energy is the energy that is stored in a current-bearing coil in the form of its magnetic field. It is the result of the work that the current has to perform in opposition to the induced voltage (Faraday’s law of induction). Conversely, this magnetic energy is released again in the form of electric current when the magnetic field collapses. Magnetic energy is also stored in a magnetized material. It is equivalent to the work that must be expended in order to align the magnetic dipoles of this material in an external magnetic field. In ferromagnetic materials, the magnetic dipoles align themselves in small zones (“Weiss domains"), even without an external magnetic field. If the Weiss domains are now aligned by an external magnetic field, a permanent magnet is produced.
Incidentally: If a permanent magnet is heated above a critical temperature, it loses its magnetization. The magnetic energy is released as additional heat at this so-called Curie temperature.

Information and ideas:
A simple experiment on magnetization: If you pass a permanent magnet over an iron nail, it magnetizes the nail. What work has to be expended for this, apart from the friction work? Is the permanent magnet or its magnetic energy “used up" in the process?
Illustration
Physics; Technology
Grade 7 to 9; Grade 10 to 13
Middle/high school; Vocational training
Chart; Energy; Generator; Magnetism; Power generation
Siemens Stiftung Media Portal
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© Siemens Stiftung 2018
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