A bar magnet has length 4 cm , cross-sectional area $2 \mathrm{~cm}^2$ and magnetic moment $6 \mathrm{Am}^2$. The intensity of magnetisation of bar magnet is

In the following graph of flux density versus magnetizing force, coercivity and retentivity are respectively represented by the points

The correct relation between total magnetic field $(B)$, magnetic intensity $(\mathrm{H})$, permeability of free space $\left(\mu_0\right)$ and susceptibility $(\chi)$ is

A magnetic intensity of $500 \mathrm{~A} / \mathrm{m}$, produces a magnetic flux of $2.4 \times 10^{-5} \mathrm{~Wb}$ in an iron bar of cross-sectional area $0.4 \mathrm{~cm}^2$. The magnetic permeability of the iron bar is