Magnet

A magnet is a device that produces a magnetic field. Wires carrying electrical current produce magnetic fields which are circular around the wire. When wires are wound into a coil these are called electro-magnets. Another type of magnet is a permanent magnet in which an atoms in the material produce a magnetic field without the need for current. Magnetic fields exert forces on moving charges. Magnetic fields are used in fusion devices to trap plasmas for heating to high temperature.

Permanent Magnet

A magnet that retains its magnetism after removal of the magnetizing force.

Historical Notes
800BC Greek texts mention the Magnetic properties of the naturally occurring lodestone were first time.
600BC Thales of Miletus, Greek philosopher and scientist, noted that iron was attracted to lodestone.
1269 Maricourt used a compass to discover that a magnet is encircled by lines which terminate on two poles.
1600 William Gilbert discovered the earth is one giant magnet.
1785 Charles Coulomb discovered the square law of attraction and repulsion between electrical charges and magnetic poles.
1820 Hans Oersted discovered that an electrical current would deflect magnetic needles.
1830 Michael Faraday discovered electromagnetic induction.
1870 Zenobe T. Gramme perfects the ring armature - the first practical electrical dynamo and the start of the era of electricity.
1873 James Maxwell published the discoveries of Gauss, Ampere and Faraday's theories of the relationship between electricity and magnetism in "Treatise on Electricity and Magnetism".
1950 Philips produced the first non-metallic magnets know as Ferrites.

See also: Alnico Magnet, Compass, Ferrimagnetism, Horseshoe Magnet, Law of Magnetism, Magnetic, Magnetic Field, Magnetism, Neodymium Iron Boron, Pole Piece, Superconducting Magnets, Temporary Magnet.

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Subjects: Electromagnetism