Q.Define magnetising field intensity $H$, magnetic permeability $\mu$, and magnetic susceptibility $\chi$ of a material, and derive the relation $\mu_r = 1+\chi$ between the relative permeability $\mu_r$ and $\chi$.

Magnetising field intensity $H$ (A/m) is the field a current source would produce in vacuum, independent of any material present. Permeability $\mu=B/H$ is the ratio of the actual flux density $B$ inside a material to $H$ (T$\cdot$m/A). Susceptibility $\chi=M/H$ is the ratio of the material's own intensity of magnetisation $M$ to $H$ (dimensionless). …

Write $B$ as the vacuum term plus the magnetisation term, divide by $H$, and identi …

• Confusing $H$ (external, source-only) with $B$ (total, includes the material). …