There is a distinction between the coercive field force BHc, the flux density, and the coercive field force IHc of the polarization. The coercive field force BHc (in the case of the closed magnetic circle) is defined as demagnetized field strength required for the removal of the flux density B. The coercive field force IHc is the demagnetized field strength whereby the polarisation becomes zero. Thus, by applying IHc, a body becomes non-magnetic. Practically speaking, all materials with high permeability are magnetic, mainly iron, nickel, cobalt, and related alloys. All other materials are non-magnetic (brass, copper, wood, stone, etc.).