It represents the extent to which a specimen is magnetised when placed in a magnetising field.

Or in other words the  intensity of magnetisation of a magnetic material is defined as the magnetic moment per unit volume of the material.

                                    M = Magnetic moment/volume = μM / V                            …1

Let       a = Uniform area of cross-section of the magnetised specimen.

            l = magnetic length of the specimen.

            m = strength of each pole of the specimen,

As                    μ_m = ml

and                   V = al

then equation (1) becomes

            M = m x 2l / a x 2l

or         M = m/a

thus intensity of magnetisation of  a  magnetic material is also defined as the pole strength per unit area of cross-section of the material.

Unit :    M= magnetic moment / Volume

            M= Amp.metre² / metre³ = Am ^-1

These are S.I unit of M

Reference: This article is referred from my book “electrical engineering materials” having ISBN: 978-81-272-5069-0.

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