| the inductance of a coil of specified geometry, placed on a given core in a specified position, divided by the square of the number of turns|
AL = L/N2
where L is the inductance of the coil when placed on the core and N is the number of turns on the coil
NOTE 1 – The inductance factor is closely related to permeance Λ; the latter refers to the reluctance of a core while inductance factor refers to the core with a winding.
NOTE 2 – In principle inductance factor can correspond to the several forms of permeability defined in the IEV, for example amplitude permeability, but unless otherwise specified it should be assumed that it corresponds to the effective permeability at vanishingly small field strengths.
NOTE 3 – The concept "turns factor" (α) has been used in the past. It was defined as : the number of turns that a coil of specified geometry, placed on a given core in a specified position, should have to obtain unit inductance (normally the millihenry):
α = N/√L