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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 relation between the magnetizing field H and the magnetic field B can also be expressed as the magnetic permeability: = / or the relative permeability = /, where is the vacuum permeability. The permeability of ferromagnetic materials is not constant, but depends on H .
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.
Common sheet metals for shielding include copper, brass, nickel, silver, steel, and tin. Shielding effectiveness, that is, how well a shield reflects or absorbs/suppresses electromagnetic radiation, is affected by the physical properties of the metal. These may include conductivity, solderability, permeability, thickness, and weight.
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.
Ferromagnetic materials are noticeably attracted to a magnet, which is a consequence of their substantial magnetic permeability. Magnetic permeability describes the induced magnetization of a material due to the presence of an external magnetic field. For example, this temporary magnetization inside a steel plate accounts for the plate's ...
Relative depth varies with temperature because resistivities and permeability vary with temperature. For steel, the relative permeability drops to 1 above the Curie temperature. Thus the reference depth can vary with temperature by a factor of 2–3 for nonmagnetic conductors and by as much as 20 for magnetic steels. [8]