What Are Some Common Electromagnetic Devices?

Common electromagnetic devices include tape recorders, loudspeakers, maglev trains and electric motors. Other common devices are electromagnetic locks, doorbells and magnets used to pick up metal scrap.

Loudspeakers use an electromagnet and a permanent magnet to produce sounds. The electromagnet is attached to the speaker cone, and moves in relation to the permanent magnet when a current is run through it. These vibrations of the speaker cone are what produce the voices and music. An electromagnet is rapidly turned on and off in a door bell, pulling the iron arm rapidly against the bell to make an alarm. Electromagnetic locks pull the lock's plunger through the door and do not release until the electromagnet is turned off.

Maglev trains use electromagnets to propel themselves forward. Permanent magnets line the bottom of the train, while electromagnets line the tracks beneath it. The train needs no wheels, as the repulsive forces between the magnets causes the train to float above the tracks. To move the train forward, the polarities of the electromagnets on the track rapidly switch, pulling the train.

Electric motors are another combination of permanent magnets and electromagnets. Electromagnets are placed on a wheel, while permanent magnets are attached to a frame next to the wheel. By varying the polarity and current running through the electromagnets, the direction and speed of the wheel's rotation can be controlled.