Intensity of Magnetization – Magnetism and Matter Class 12

Class 9-10, JEE & NEET

Intensity of Magnetization represents the extent to which a specimen is magnetised when placed in a magnetising field. Or in other words the intensity of magnetisation is defined as the magnetic dipole moment developed per unit volume when a magnetic material is subjected to magnetising field. Intensity of magnetisation $I =\frac{\text { magnetic dipole moment }}{\text { volume }}=\frac{M}{V}$
1. It is a vector quantity whose direction is along the direction of magnetising field.
2. Its SI unit is ampere/m (A/m) and dimensions is $M^{0} L^{-1} T^{0} A^{1}$
3. The intensity of magnetisation shows the extent to which the substance is magnetised.
4. $I=\frac{M}{V}=\frac{m \times 2 \ell}{A \times 2 \ell}=\frac{m}{A}$ . Intensity of magnetisation is also defined as pole strength developed per unit area of cross-section of specimen.
5. I depends on nature of material.
6. I depends on temperature.

#### Different relations for Intensity of magnetisation.

• Volume intensity of magnetisation $I=\frac{M}{V}$
• Mass intensity of magnetisation $I _{ mass }=\frac{1}{\rho}\left(\frac{ M }{ V }\right)=\frac{ I }{\rho}$ where $\rho$is density of material
• Molar intensity of magnentisation $I _{\text {molar }}=\frac{W}{\rho}\left(\frac{ M }{ V }\right)=\left(\frac{ W }{\rho}\right) I$ where W is atomic weight of substance
• Molecular intensity of magnetisation $I _{\text {molecular }}=\frac{W}{\rho N}\left(\frac{ M }{ V }\right)=\frac{ W }{ N } I _{\text {mass }}=\frac{ I _{\text {molar }}}{ N }$ where N is Avogadro’s number.