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In SI units, permeability is measured in henries per meter (H/m), or equivalently in newtons per ampere squared (N/A 2). The permeability constant μ 0, also known as the magnetic constant or the permeability of free space, is the proportionality between magnetic induction and magnetizing force when forming a magnetic field in a classical vacuum.
An important effect in metals under strong magnetic fields, is the oscillation of the differential susceptibility as function of 1 / H . This behaviour is known as the De Haas–Van Alphen effect and relates the period of the susceptibility with the Fermi surface of the material.
The definitions for monopoles are of theoretical interest, although real magnetic dipoles can be described using pole strengths. There are two possible units for monopole strength, Wb (Weber) and A m (Ampere metre). Dimensional analysis shows that magnetic charges relate by q m (Wb) = μ 0 q m (Am).
The magnetic diffusion equation (also referred to as the induction equation) is = [] + where is the permeability of free space and is the electrical conductivity of the material, which is assumed to be constant.
The vacuum magnetic permeability (variously vacuum permeability, permeability of free space, permeability of vacuum, magnetic constant) is the magnetic permeability in a classical vacuum. It is a physical constant , conventionally written as μ 0 (pronounced "mu nought" or "mu zero").
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;
The magnetic diffusivity has SI units of m²/s and is defined as: [2] =, while in Gaussian units it can be defined as =. In the above, μ 0 {\displaystyle \mu _{0}} is the permeability of free space , c {\displaystyle c} is the speed of light, and σ 0 {\displaystyle \sigma _{0}} is the electrical conductivity of the material in question.
In electromagnetism, permeance is the inverse of reluctance.In a magnetic circuit, permeance is a measure of the quantity of magnetic flux for a number of current-turns. A magnetic circuit almost acts as though the flux is conducted, therefore permeance is larger for large cross-sections of a material and smaller for smaller cross section lengths.