An internal magnetic field in magnetics

One more magnetic characteristic, a magnetic permeability p, is usually introduced it shows how much the magnetic induction in a magnetic B is larger then that of the external magnetic field Bq. 

This means that this value should be substituted into the Bio-Savare law (5.1.16) 

Find the relation of the magnetic magnetization 3 and the surface density of the current p. According to eqn (5.2.3), the magnetization is the magnetic moment of the unit volume. Therefore for this case 

The expressions obtained allow one to find a ratio outside and inside of the magnetic and to establish the ratio between a magnetic susceptibility and magnetic permeability. The macroscopic field in a substance is characterized by a magnetic induction which is the geometrical sum of magnetic inductions of the external Bq and internal fields, i.e. 

Having replaced in iMs expression Bg andBj according to (5.2.9) and (5.2.11), and taking also into account a coIUnear arrangonent of all three vectors, we obtain 

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