Electromagnet is a type of magnet in which the magnetic field is produced by the flow of an electric current through the coil. The magnetic field disappears when the current ceases.
As a current is passed through the coil, small magnetic regions within the material, called magnetic domains, align with the applied field, causing the magnetic field strength to increase. As the current is increased, all of the domains eventually become aligned, a condition called saturation.
The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be rapidly manipulated over a wide range by controlling the amount of electric current. However, a continuous supply of electrical energy is required to maintain the field.
In applications where a variable magnetic field is not required, permanent magnets are generally superior. Additionally, permanent magnets can be manufactured to produce stronger fields than electromagnets of similar size.
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.
Popular uses: linear motor, electric motor, circuit-breakers, electromagnet brakes, electromagnet clutches, metal lifter, magnetic separators, and more.
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