Electromagnet

Electromagnet, device consisting of a core of magnetic material surrounded by a coil through which an electric current is passed to magnetize the core. An electromagnet is used wherever controllable magnets are required, as in contrivances in which the magnetic flux is to be varied, reversed, or switched on and off. The engineering design of electromagnets is systematized by means of the concept of the magnetic circuit. In the magnetic circuit a magnetomotive force F, or Fm, is defined as the ampere-turns of the coil that generates the magnetic field to produce the magnetic flux in the circuit. Thus, if...