magnetic diffusivity

magnetic diffusivity

[mag′ned·ik ‚di‚fyü′siv·əd·ē] (electromagnetism) A measure of the tendency of a magnetic field to diffuse through a conducting medium at rest; it is equal to the partial derivative of the magnetic field strength with respect to time divided by the Laplacian of the magnetic field, or to the reciprocal of 4πμσ, where μ is the magnetic permeability and σ is the conductivity in electromagnetic units.