An electropermanent magnet or EPM is a type of permanent magnet in which the external magnetic field can be switched on or off by a pulse of electric current in a wire winding around part of the magnet. The magnet consists of two sections, one of "hard" (high coercivity) magnetic material and one of "soft" (low coercivity) material. The direction of magnetization in the latter piece can be switched by a pulse of current in a wire winding. When the magnetically soft and hard materials have opposing magnetizations the magnet produces no net external field across its poles, while when their direction of magnetization is aligned the magnet produces an external magnetic field.
Before the electropermanent magnet was invented, applications needing a controllable magnetic field required electromagnets, which consume large amounts of power when operating. Electropermanent magnets require no power source to maintain the magnetic field. Electropermanent magnets made with powerful rare-earth magnets are used as industrial lifting (tractive) magnets to lift heavy ferrous metal objects; when the object reaches its destination the magnet can be switched off, releasing the object. Programmable magnets are also being researched as a means of creating self-building structures. Wikipedia, electropermanent magnet
See Also
bar magnet
electromagnet
electromagnetic sympathetic attraction
Enhanced Electromagnetic Spectrum Table
Figure 1.8 - Electromagnetic Scale in Octaves
Figure 17.04 - Gravity Pressure Recorder - Bar Magnet
Figure 3.34 - Electric and Magnetic Vectors
Figure 7B.16 - Bar Magnets shown separate then joined as one
Figure 7B.17 - Multiplying Force to Poles of a Bar Magnet
Figure 7B.18 - Four Poles of a Bar Magnet
Figure 7B.19 - Magnetic Lines of Force developed from Induction of Current Flow
law of electromagnetic induction
Light Rings formed at 90 Degrees to Magnetic Center Line
Magnet
Magnet Keeper
magnetic field
magnetic outreach
Part 16 - Electricity and Magnetism
3.17 - Magnetic Electric Poles
7B.20 - Magnetism