5 Magnetisation and Magnetic Intensity
Magnetisation and Magnetic Intensity
- Magnetic intensity − It is given by the relation,
Where,
B0 → Magnetic field inside vacuum
μ0 → 4π × 10−7 TmA−1
SI unit → Am−1
- Intensity of magnetisation − It is defined as the magnetic moment developed per unit volume when a magnetic specimen is subjected to magnetising field. It is denoted by I.
SI unit → Am−1
- Magnetic Induction − It is defined as the number of magnetic lines of induction crossing per unit area through the magnetic substance. It is denoted by B.
Magnetic induction B is the sum of the magnetic field B0 and the magnetic field μ0I produced due to the magnetisation of the substance. Thus,
B = B0 + μ0I = μ0H + μ0I
B = μ0 (H + I) …(ii)
- Magnetic susceptibility − The magnetic susceptibility of a magnetic substance is defined as the ratio of the intensity of magnetisation to the magnetic intensity. It is denoted byχm.
- Magnetic permeability − The magnetic permeability of a magnetic substance is defined as the ratio of the magnetic induction to the magnetic intensity. It is denoted by μ.
Now, on dividing both sides of the equation (ii) by H, we obtain
From equation (iii), we have
However, 
