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. $2.4\mathrm{\pi }\times {10}^{-4} \mathrm{T} \mathrm{m} {\mathrm{A}}^{-1}$