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 :
(μ0 = 4π × 10-7 T m A-1)
(1) 2.4π × 10-4 T m A-1
(2) 8.0 × 10-5 T m A-1
(3) 2.4π × 10-5 T m A-1
(4) 2.4π × 10-7 T m A-1