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Electricity and Magnetism (book) Electromagnet; Electromagnetic brake; Electromagnetic buoyancy; Electromagnetic cavity; Electromagnetic clutch; Electromagnetic field;
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An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire (likely copper) wound into a coil. A current through the wire creates a magnetic field which is concentrated along the center of the coil. The magnetic field disappears when the current is turned off.
Drawings of patent US687292, showing a first-order motor with electromagnets on one of the gears. A magnetic gear resembles the traditional mechanical gear in geometry and function, using magnets instead of teeth. As two opposing magnets approach each other, they repel; when placed on two rings, the magnets will act like teeth.
The design of sextupoles using electromagnets generally involves six steel pole tips of alternating polarity. The steel is magnetised by a large electric current that flows in the coils of wire wrapped around the poles. The coils may be formed from hollow copper magnet wire that carry coolant, usually de-ionized water.
Electromagnetic suspension (EMS) is the magnetic levitation of an object achieved by constantly altering the strength of a magnetic field produced by electromagnets using a feedback loop. In most cases the levitation effect is mostly due to permanent magnets as they have no power dissipation, with electromagnets only used to stabilise the effect.
Pole pieces are used with both permanent magnets and electromagnets. In the case of an electromagnet, the pole piece or pieces simply extend the magnetic core and can even be regarded as part of it, particularly if they are made of the same material. In the case of a permanent magnet, the distinction between the magnet itself and the pole piece ...
When electric currents are used to produce a magnet in this way, it is called an electromagnet. Electromagnets often use a wire curled up into solenoid around an iron core which strengthens the magnetic field produced because the iron core becomes magnetised.