magnetiseringsstyrken

Magnetiseringsstyrken, commonly referred to as the magnetizing field strength, is the component of the magnetic field that drives magnetisation in materials. In SI units it is denoted by H and measured in amperes per metre (A/m). The magnetising field is produced by free electric currents in conductors, such as coils surrounding a magnetic core, and can also arise from permanent magnets in certain configurations.

In the SI framework the total magnetic field B in a material relates to H and the material’s magnetisation M by B = μ0(H + M). For linear, isotropic materials this simplifies to B = μ μ0 H, where μ = 1 + χ is the absolute permeability and χ is the magnetic susceptibility. The relationship between H and M depends on the material: M typically increases with H, but in ferromagnets the M–H curve is nonlinear and exhibits hysteresis. At high values of H, materials approach magnetic saturation, after which further increases in H yield little additional B.

Practically, magnetiseringsstyrken is central to the design and operation of transformers, inductors, and magnetic circuits. Engineers control H through the number of coil turns and the current, as well as the geometry of the magnetic path, to achieve the desired flux while avoiding excessive core losses or saturation.

See also: magnetic field, magnetic flux density, permeability, hysteresis, saturation.