Glossary

Residual Induction( Br): The magnetic induction corresponding to zero magnetizing force in a magnetic material after saturation in a closed circuit; measured in gauss or tesla.

Coercive Force( Hcb): The value of demagnetizing force that reduces residual induction to zero. Measure of how permanent a magnet is; permanent magnets have a high coercivity. The intensity of a magnetic field needed to demagnetize a substance.The maximum coercive force, as measured on a saturated magnet, is proportional to the remanent flux density. See “flux density.” It is expressed in oersteds or kiloAmps per meter (kA/m).

Intrinsic Coercive ForceHci: Indicates a material’s resistance to demagnetization. It is equal to the demagnetizing force which reduces the intrinsic induction, Bi, in the material to zero; measured in oersteds (or kA/m). As for coercivity, the maximum value of intrinsic coercivity is obtained after the material has been saturated (fully magnetized).

Max Energy Product(BHmax): The point on the Demag- netization Curve where the product of B and H is a maximum and the required volume of magnet material required to project a given energy into its surroundings is a minimum. Measured in Mega Gauss Oersteds, MGOe.

Curie Temperature(Tc) : The temperature at which the parallel alignment of elementary magnetic moments completely disap- pears, and the material is no longer able to hold magnetization.

Magnetic Flux: The total magnetic induction over a certain area.

Induction B : The magnetic flux per unit area of a section normal to the direction of flux. Measured in Gauss, in the cgs system of units.

Demagnetization Curve :The second quadrant of the hysteresis loop, generally describing the behavior of magnetic characteristics in actual use, also known as the B-H curve.

Hysteresis Loop: A closed curve obtained for a material by plotting corresponding values of magnetic induction, B, (on the abscissa) against magnetizing force, H, (on X axis, Y axis).

Isotropic Magnet: A magnet material whose magnetic proper- ties are the same in any direction, and which can therefore be magnetized in any direction without loss of magnetic character-

Anisotropic Magnet: A magnet having a preferred direction of magnetic orientation, so that the magnetic characteristics are optimum in one preferred direction.

Magnetic Field Strength:  A measurement of the magnetic ability to induce a magnetic field at a given point. This is measured in Oersteds.

Leakage Flux: That portion of the magnetic flux that is lost through leakage in the magnetic circuit due to saturation or air-gaps, and is therefore unable to be used.

Magnetizing Force, H: The magnetomotive force per unit length at any point in a magnetic circuit. Measured in Oersteds in the CGS system.

North Pole: That pole of a magnet which, when freely sus- pended, would point to the north magnetic pole of the earth. The definition of polarity can be a confusing issue, and it is often best to clarify by using “north seeking pole” instead of “north pole” in specifications.

Oersted (Oe): A CGS unit of measure used to describe magne- tizing force. The English system equivalent is Ampere Turns per Inch, and the SI system’s is Ampere Turns per Meter.

Direction of Magnetization : The direction in which an anisotropic magnet should be magnetized in order to achieve optimum magnetic properties.

Stabilization: Exposure of a magnet to demagnetizing influ- ences expected to be encountered in use in order to prevent irreversible losses during actual operation. Demagnetizing influences can be caused by high or low temperatures, or by external magnetic fields.