Various Magnetic Quantities

Quantity Symbol [Units] Physical Meaning
 Total magnetic field
   (also known as
    magnetic flux density)
B[T]  The total magnetic field determines magnetic interaction such as the Lorentz force, F = qv´B.  B = B0 + μ0M =  μ0(H + M)
 External field B0[T]  The portion of the magnetic field in a substance due to current-carrying components
 Magnetization field Bm[T]  Field in a substance due the substance itself, Bm = μ0M
 Magnetic field strength H[A/m]  H = B0/μ0 is used to represent the effects of external currents in wires
 Magnetization vector M[A/m]  Magnetic moment per unit volume of substance. 
 Magnetic susceptibility χ [ ]  Expresses relationship between the magnetic field strength and the magnetization vector, MχH. (Holds for para- and di-
 but not for ferro-magnetic substances. χ is positive for paramagnetic substances and negative for diamagnetic substances.)
 Magnetic permeability μm[T×m/A]  Expresses the relationship between the total magnetic field and the magnetic field strength, B = μmH.  Note that μm 0(χ + 1).