permeability

(noun)

A quantitative measure of the degree of magnetization of a material in the presence of an applied magnetic field (measured in newtons per ampere squared in SI units).

Related Terms

  • ferromagnet
  • inductor

Examples of permeability in the following topics:

  • Nerve Conduction and Electrocardiograms

    • In its resting state, the cell membrane is permeable to K+ and Cl−, and impermeable to Na+.
    • Electric currents along the cell membrane are created by any stimulus that changes the membrane's permeability.
    • The membrane thus temporarily becomes permeable to Na+, which then rushes in, driven both by diffusion and the Coulomb force.
    • The changing voltage and electric fields affect the permeability of the adjacent cell membrane, so that the same process takes place there.
  • Ampere's Law: Magnetic Field Due to a Long Straight Wire

    • In this equation, dl represents the differential of length of wire in the curved wire, and μ0 is the permeability of free space.
  • Paramagnetism and Diamagnetism

    • Paramagnetic materials have a relative magnetic permeability greater or equal to unity (i.e., a positive magnetic susceptibility) and hence are attracted to magnetic fields.
  • Energy in a Magnetic Field

    • For linear, non-dispersive, materials (such that B = μH where μ, called the permeability, is frequency-independent), the energy density is:
  • Electric Currents and Magnetic Fields

    • For a long straight wire where I is the current, r is the shortest distance to the wire, and the constant 0=4π10−7 T⋅m/A is the permeability of free space.
    • where the magnetic field is integrated over a curve (circumfrence of a wire), equivalent to integrating the current density (in amperes per square meter, Am-2) over the cross section area of the wire (which is equal to the permeability constant times the enclosed current Ienc).
  • Ferromagnets and Electromagnets

    • Due to the high magnetic permeability μ of the ferromagnetic material, the ferromagnetic core increases the magnetic field to thousands of times the strength of the field of the coil alone.
  • Molecular Transport Phenomena

    • Membranes are generally selectively permeable, or semipermeable.
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