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For example, 4% electrical steel has an initial relative permeability (at or near 0 T) of 2,000 and a maximum of 38,000 at T = 1 [5] [6] and different range of values at different percent of Si and manufacturing process, and, indeed, the relative permeability of any material at a sufficiently high field strength trends toward 1 (at magnetic ...
where μ 0 is the vacuum permeability (see table of physical constants), and (1 + χ v) is the relative permeability of the material. Thus the volume magnetic susceptibility χ v and the magnetic permeability μ are related by the following formula: = (+).
The permeability of ferromagnetic materials is not constant, but depends on H. In saturable materials the relative permeability increases with H to a maximum, then as it approaches saturation inverts and decreases toward one. [2] [3] Different materials have different saturation levels.
Highly magnetic materials have a reduced skin depth owing to their large permeability as was pointed out above for the case of iron, despite its poorer conductivity. A practical consequence is seen by users of induction cookers , where some types of stainless steel cookware are unusable because they are not ferromagnetic.
The typical relative permeability (μ r) of electrical steel is 4,000-38,000 times that of vacuum, compared to 1.003-1800 for stainless steel. [ 15 ] [ 16 ] [ 17 ] The magnetic properties of electrical steel are dependent on heat treatment , as increasing the average crystal size decreases the hysteresis loss.
It is a measure of material permeability variation after demagnetization, given by a formula = (), where , are permeability values, and t 1, t 2 are time from demagnetization; usually determined for t 1 = 10 min, t 2 = 100 min; range from 2×10 −6 to 12×10 −6 for typical MnZn and NiZn ferrites;
Alnico magnets produce magnetic field strength at their poles as high as 1500 gauss (0.15 tesla), or about 3000 times the strength of Earth's magnetic field. Some alnico brands are isotropic and can be efficiently magnetized in any direction.
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 ...