Ten Uses of an Electromagnet
The electromagnetic effect, discovered in the early 1800s, is an feature found in many things we use in everyday life. Since it can apply force to metals, it's essential to the operation of such parts as relays, solenoids and motors. The same force is used in recycling to separate metals from waste materials. It is also used for heavy lifting. Electromagnets also manipulate subatomic particles in uses including MRIs and particle accelerators.
Other People Are Reading
-
Solenoids and Relays
-
A solenoid is a spring-loaded metal slug inside an electromagnetic coil. When it's powered on, the solenoid either pulls in or pops out, depending on the design. You'll find solenoids in car starters, electronic door locks and pinball machines.
Relays are switches turned on and off by an electromagnet. When the current is turned on, the magnet attracts spring-loaded metal contacts, making an electrical connection. When the current is off, the spring pushes the contacts apart, breaking the connection.
Direct Current Motors
-
Inside every direct current motor are electromagnets on a rotor set next to permanent magnets. The magnetic fields repel each other, forcing the rotor to spin. As the rotor spins, the electromagnets' fields reverse, repelling them from the next set of permanent magnets. The process repeats through the full rotation, keeping the motor running.
-
Analog Meters
-
The dial pointer on an analog meter is attached to a moving coil mounted on a pivot. The coil's magnetic field opposes a permanent magnet's field, moving the needle on the pivot. The more current flowing through the coil, the farther the needle moves.
Salvage Crane Magnets & Metal Separators
-
Salvage yards use large, crane-mounted electromagnets to move tons of scrap metal at a time. A generator in the crane provides the power for the magnet.
Recycling and salvage operations separate ferrous (iron-bearing) from non-ferrous metals and other materials with an electromagnet. A conveyor belt carries scrap under the magnet, which pulls it out of the material stream.
Speakers
-
A speaker consists of a permanent magnet, a coil and a cone-shaped membrane attached to the coil. When audio-frequency current flows through the coil, it creates a magnetic field that pushes and pulls against the permanent magnet's field. The back-and-forth motion moves the cone to make sound.
CRTs
-
Electromagnets are a part of every television set or computer monitor that uses a cathode-ray tube. Four coils, set in a "yoke" around the neck of the tube, generate changing magnetic fields. They steer the electrons in their path to the phosphor screen, creating the familiar TV or computer image.
Particle Accelerators and MRIs
-
CERN, Fermilab, and other research institutes use superconducting electromagnets wrapped around the accelerator tunnel. They propel subatomic particles to nearly the speed of light.
A magnetic resonance imaging (MRI) machine uses a powerful superconducting electromagnet. The strong magnetic field lets it resolve all the tissues in the human body.
-
