GLOSSARY OF MAGNETIC TERMINOLOGY
Anisotropic (oriented) - The material has a preferred direction of magnetic orientation.
Coercive Force, Hc - The demagnetizing force, in oersteds, required to reduce the residual induction, Br, of a fully magnetized magnet to zero.
Curie Temperature - Temperature at which a material loses its magnetic properties.
Ferrite - A ceramic compound consisting of a mixed oxide of iron and one or more other metals. Many of them are magnetic materials.
Ferrous Metal - The term "ferrous" is derived from the Latin word meaning "containing iron". Ferrous metals are often magnetic, but not exclusively.
Gauss - Unit of measure of magnetic induction, B, or flux density in the CGS system.
Gaussmeter - An instrument used to measure the instantaneous value of magnetic induction, B.
Intrinsic Coercive Force, Hci - Oersted measurement of the material’s inherent ability to resist self-demagnetization.
Isotropic (non-oriented) - The material has no preferred direction of magnetic orientation, which allows magnetization in any direction.
Megagauss-oersteds (MGOe) - The stored energy in a magnet, called magnet performance or magnetic energy product, is typically measured in units of megagauss-oersteds.
Magnetic Induction, B - Flux per unit area of a section normal to the direction of the magnetic path. Measured in gauss.
Maximum Energy Product, BHmax - The maximum product of (BdHd) which can be obtained on the demagnetization curve.
Maximum Operating Temperature - The maximum temperature of exposure that a magnet can forego without significant long-range instability or structural changes.
North Pole - That magnetic pole which attracts the geographic North Pole.
Residual Induction, Br - Flux density, measured in gauss, of a magnetic material after being fully magnetized in a closed circuit.
What is a Magnet?
A magnet is an object made of certain materials which create a magnetic field. Every magnet has at least one north pole and one south pole. By convention, we say that the magnetic field lines leave the North end of a magnet and enter the South end of a magnet. This is an example of a magnetic dipole ("di" means two, thus two poles). If you take a bar magnet and break it into two pieces, each piece will again have a North pole and a South pole. If you take one of those pieces and break it into two, each of the smaller pieces will have a North pole and a South pole. No matter how small the pieces of the magnet become, each piece will have a North pole and a South pole. It has not been shown to be possible to end up with a single North pole or a single South pole which is a monopole ("mono" means one or single, thus one pole).
Amazing Magnetic Facts
Did you know that the name “magnet” was first used by the Greeks as Early as 600 B.C. for describing a mysterious stone that attracted iron and other pieces of the same material? According to one Greek legend, the name “magnet” was taken from the shepherd “Magnes” who discovered the magnetic stone by accident when his staff was mysteriously attracted to the force of the stone. Another, and perhaps more believable, theory says that the word “magnet” came from a city in Asia Minor, called Magnesia, where many of these mysterious magnetic stones were found. During the Middle Ages, this stone became known as lodestone, which is the magnetic form of magnetite.
Today, magnets are available in all sorts of shapes including discs, rings, blocks, rectangles, arcs, rods, and bars. They are made out of materials such as ceramic (strontium ferrite), alnico (aluminum, nickel, and cobalt), rare earth (samarium cobalt and neodymium) and flexible rubber-like material. Not only do the shape and material of magnets vary, so do their applications. At many companies, magnets are used for lifting, holding, separating, retrieving, sensing and material handling. You can find magnets in a car — even around your house! Magnets are used in the home to organize tools or kitchen utensils and can be found in doorbells, loudspeakers, microwaves and televisions! Business offices and schools use magnetic planning boards to display schedules and charts.
Magnets are also used in a compass to guide people if they are lost. In fact, the compass was probably the first important magnetic device discovered. Around the 12th century, someone noticed that when allowed free movement, a magnet always points in the same north/south direction. This discovery helped mariners who often had trouble navigating when the clouds covered the sun or stars.