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Glossary of magnet terminology
Anisotropic Magnet
A magnet having a preferred direction of magnetic orientation.
Isotropic magnet
A magnet material whose magnetic properties are the same in any direction.
Coercive force, Hc
The demagnetizing force, measured in Oersteds necessary to reduce the induction, B to zero after a magnet has been previously saturated.
Curie temperature, Tc
The transition temperature above which a material looses its magnetic properties.
The condition existing in a material subjected to magnetizing force. The unit of flux is the Maxwell.
Lines of magnetic flux per square centimeter. This is a measure of flux density.
Induction, B
The magnetic flux per unit area of a section normal to the direction of flux. This is measured in Gauss.
Intrinsic Coercive Force, Hci
This is a measure of a materials ability to resist demagnetization. This is measured in Oersteds.
Irreversible Loss
This is defined as the partial demagnetizing of a magnet caused by external factors.
Magnetic Field strength, H
A measurement of the magnetic ability to induce a magnetic field at a given point. This is measured in Oersteds.
Magnetic Flux
The total magnetic induction over a certain area.
Magnetizing Force, H
The magnetomotive force per unit length at any point in the magnetic circuit. this is measured in Oersteds.
Magnetomotive Force, F
The magnetic potential difference between any two points.
A unit of magnetic flux. One Maxwell is one line of magnetic flux.
Oersted, Oe
A unit of magnetic field strength or magnetizing force.
Orientation Direction
The direction in which an anisotropic magnet should be magnetized in order to optimize the magnetic properties.
This is a condition where all magnetic moments have become oriented in one direction.
Exposing a magnet to demagnetizing influences which are expected in the application in order to prevent irreversible loss during the operation of the magnet. 
(BH) max
Maximum energy product, is the maximum product of (BrHd) which can be obtained on the demagnetization curve. 
Air gap, is a low permeability gap in the flux path of a magnetic circuit. Often air, but inclusive of other materials such as paint, aluminum, etc.
Br, Residual induction (or flux density),
It is the magnetic induction corresponding to zero magnetizing force in a magnetic material after saturation in a closed circuit; measured in gauss. 
A gauss meter is an instrument that measures the instantaneous value of magnetic induction, B. 
A hysteresis loop(hysteresis graph) is a closed curve obtained for a material by plotting (usually to rectangular coordinates) corresponding values of magnetic induction, B, for ordinates and magnetizing force, H, for abscissa when the material is passing through a complete cycle between definite limits of either magnetizing force, H, or magnetic induction. B. 
Knee of the demagnetization curve is the point at which the B-H curve ceases to be linear. All magnet materials, even if their second quadrant curves are straight line at room temperature, develop a knee at some temperature.