An iron rod of susceptibility \(599\) is subjected to a magnetising field of \(1200\) A m^-1. The permeability of the material of the rod is:$({\mathrm{\mu }}_0=4\mathrm{\pi }\times {10}^{-7}$ $\mathrm{T}$ $\mathrm{m}$ ${\mathrm{A}}^{-1})$
1. $8.0\times {10}^{-5}$ $\mathrm{T}$ $\mathrm{m}$ ${\mathrm{A}}^{-1}$
2. $2.4\mathrm{\pi }\times {10}^{-5}$ $\mathrm{T}$ $\mathrm{m}$ ${\mathrm{A}}^{-1}$
3. $2.4\mathrm{\pi }\times {10}^{-7}$ $\mathrm{T}$ $\mathrm{m}$ ${\mathrm{A}}^{-1}$
4. $2.4\mathrm{\pi }\times {10}^{-4}$ $\mathrm{T}$ $\mathrm{m}$ ${\mathrm{A}}^{-1}$