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Coercivity, also called the magnetic coercivity, coercive field or coercive force, is a measure of the ability of a ferromagnetic material to withstand an external magnetic field without becoming demagnetized. Coercivity is usually measured in oersted or ampere/meter units and is denoted H C.
Ferromagnetism is a property of certain materials (such as iron) that results in a significant, observable magnetic permeability, and in many cases, a significant magnetic coercivity, allowing the material to form a permanent magnet. Ferromagnetic materials are noticeably attracted to a magnet, which is a consequence of their substantial ...
During the 20th century, the maximum energy product of commercially available magnetic materials rose from around 1 MGOe (e.g. in KS Steel) to over 50 MGOe (in neodymium magnets). [4] Other important permanent magnet properties include the remanence ( B r ) and coercivity ( H c ); these quantities are also determined from the saturation loop ...
Ferrites can be divided into two groups based on their magnetic coercivity, their resistance to being demagnetized: [2] "Hard" ferrites have high coercivity, so are difficult to demagnetize. They are used to make permanent magnets for applications such as refrigerator magnets, loudspeakers, and small electric motors.
In electromagnetism, the magnetic susceptibility (from Latin susceptibilis ' receptive '; denoted χ, chi) is a measure of how much a material will become magnetized in an applied magnetic field. It is the ratio of magnetization M ( magnetic moment per unit volume ) to the applied magnetic field intensity H .
Neodymium has a negative coefficient, meaning the coercivity along with the magnetic energy density (BH max) decreases as temperature increases. Neodymium-iron-boron magnets have high coercivity at room temperature, but as the temperature rises above 100 °C (212 °F), the coercivity decreases drastically until the Curie temperature (around 320 ...
Alnico's remanence (B r) may exceed 12,000 G (1.2 T), its coercivity (H c) can be up to 1000 oersteds (80 kA/m), its maximum energy product ((BH) max) can be up to 5.5 MG·Oe (44 T·kA/m). Therefore, alnico can produce a strong magnetic flux in closed magnetic circuits, but has relatively small resistance against demagnetization.
Cassette tape label with coercivity (a measure of the external magnetic flux required to magnetize the tape) measured in oersteds. The oersted is defined as a dyne per unit pole. [clarification needed] [6] The oersted is 1000 / 4π (≈79.5775) amperes per meter, in terms of SI units. [7] [8] [9] [10]