An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. The magnetic field disappears when the current is turned off. Electromagnets usually consist of insulated wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the hole in the center of the coil. The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet.
The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be quickly changed by controlling the amount of electric current in the winding. However, unlike a permanent magnet that needs no power, an electromagnet requires a continuous supply of current to maintain the magnetic field.
Electromagnets are widely used as components of other electrical devices, such as motors, generators, relays, loudspeakers, hard disks, MRI machines, scientific instruments, and magnetic separation equipment. Electromagnets are also employed in industry for picking up and moving heavy iron objects such as scrap iron and steel. Wikipedia, Electromagnet
See Also
Coil
Electric Coil
Electropermanent magnet
Optic Dynamo
Optic Dynamo-Generator - Pages 1-5
Optic Dynamo-Generator - Pages 41-46
Optic Dynamo-Generator - Pages 47-50
Original Opti Dynamo-Generator Document
Polar Interchange - Bibliography
Polar Interchange - Device Design
Polar Interchange - Part I - See Also
Polar Interchange - Part I
Polar Interchange - Part II
Polar Interchange - Part III
Polar Interchange - Part IV
Polar Interchange - Table of Contents
Russell Optic Generator
Russells Optic Dynamo-Generator
Solenoid