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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 ...
Placing the magnet in an alternating magnetic field with intensity above the material's coercivity and then either slowly drawing the magnet out or slowly decreasing the magnetic field to zero. This is the principle used in commercial demagnetizers to demagnetize tools, erase credit cards, hard disks , and degaussing coils used to demagnetize ...
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 ...
The intercepts h c and m rs are the coercivity and saturation remanence. Magnetic hysteresis occurs when an external magnetic field is applied to a ferromagnet such as iron and the atomic dipoles align themselves with it. Even when the field is removed, part of the alignment will be retained: the material has become magnetized. Once magnetized ...
"Soft" magnetic materials with low coercivity and hysteresis, such as silicon steel, or ferrite, are usually used in cores. Magnetic field (green) created by a current-carrying winding (red) in a typical magnetic core transformer or inductor, with the iron core C forming a closed loop, possibly with air gaps G in it. The drawing shows a section ...
A recent study by the University of Southern California revealed that exposure to air pollution can harm children's learning and memory, the LA Post reports.. Ammonium nitrate, a specific ...
The larger the magnetic region is and the higher the magnetic coercivity of the material, the more stable the medium is. Conversely, there is a minimum stable size for a magnetic region at a given temperature and coercivity. If it is any smaller it is likely to be spontaneously de-magnetized by local thermal fluctuations.