| under sinusoidal conditions in a medium where the phasors B and H representing respectively the magnetic flux density and the magnetic field strength are linearly related, complex quantity μr defined by the relation
B = μ0μr H
where μ0 is the magnetic constant
NOTE 1 – The complex relative permeability is generally frequency dependent. For an isotropic medium the complex relative permeability is a scalar; for an anisotropic medium it is a tensor.
NOTE 2 – Generally μr is expressed as μr = μ'r − jμ''r where μ'r is the real relative permeability and μ''r is the magnetic loss index which represents the magnetic losses.