Flux Density (B): This is the measurement (in Gauss or Tesla) you get when you use a gaussmeter at the surface of a magnet. The reading is completely dependent on the distance from the surface, the shape of the magnet, the exact location measured, the thickness of the probe and of the magnet¡¯s plating. This is not a good way to compare magnets, since B varies so much by different measurement techniques.

Residual Flux Density (Br): Br is the maximum flux a magnet can produce, measure only in a closed magnetic circuit. The value of Br is a very good way to compare magnet strength. But remember a magnet in a closed magnetic circuit doesn¡¯t do any good for anything except test measurement.

Magnetic Field Strength (H): It signifies the value and direction of a magnet field and can defined in many ways.

Coercive Force also Coercivity (Hc): This measures a magnet¡¯s resistance to demagnetization. It is the external magnetic field strength needed to magnetize, demagnetize or remagnetize a material. The unit of it is Gauss or Tesla.

B-H Curve: Also called ¡°hysteresis loop¡±. The product of Br and Hc (Coercivity) is BHmax. The quality of magnetic materials is best expressed by the Maximum Energy Product (BHmax), measured in MegaGauss Oested (MGOe).

Intrinsic Coercive Force (Hci): Measured in Oersted in the cgs system, this is a measure of material¡¯s inherent ability to resist demagnetization. It is the demagnetization force corresponding to zero intrinsic induction. Practical consequences of high Hci values are seen in greater temperature stability for a given class of material, and greater stability in dynamic operating conditions.

Curie Temperature (Tc): This is the temperature at which a magnetic material permanently loses it¡¯s strength. Another useful value is Tmax, the recommended operating temperature. A magnet will start to lose its power when the temperature is above Tmax.

Anisotropic Magnets: During the production process, a preferential direction is applied to anisotropic magnet by an external magnetic field. In a magnetizing process followed later, the maximum magnetic values are obtained in this direction.

Isotropic Magnets: This kind of magnet can be magnetized in all directions with the identical magnetic features.

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