Electromagnet

An electromagnet is a type of magnet in which the magnetic field is produced by a flow of electric current. The magnetic field disappears when the current ceases.

Devices that use electromagnets

Electromagnets are used in many situations where a rapidly or easily variable magnetic field is desired. Many of these applications involve deflection of charged particle beams; the cathode ray tube and mass spectrometer fall into this category.

Related Topics:
Charged particle beam - Cathode ray tube - Mass spectrometer

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Other devices cause electromagnetic fields to interact with fields from permanent magnets and produce forces. Electromagnetic actuators take advantage of the fact that, if the core of a solenoid is displaced toward one end of the coil, a force will occur tending to push the core farther in that direction. Typical uses include relays, electromagnetic door locks, and solenoid valves. Doorbells and similar devices are commonly made by causing the moving core to strike a bell.

Related Topics:
Force - Actuator - Relay - Lock - Solenoid valve - Doorbell - Bell

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Electromagnets are the essential components of many circuit-breakers, they are used in cars in electromagnet brakes and clutches. In some trams, electromagnetic brakes grip directly on to the rails, very high powered electromagnets are even used to lift very heavy scraps of metal. Magnetic levitation trains use powerful electromagnets to hover without touching the track. Some trains use attractive forces, while others use repulsive forces.

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Electromagnets are used in a rotary electric motor to produce a rotating magnetic field that turns the rotor, or in a linear motor to produce a travelling magnetic field that propels the projectile.

Related Topics:
Electric motor - Linear motor

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