A mild steel toroidal ring, of cross sectional area 300mm^2 and a mean diameter of 160mm has a relative permeability of 1200 and 800 at flux densities of 0.6T and 1.2T respectively. Calculate the mmf required to produce a flux of 360 micro webbers in the ring. Calculate the reluctance of the mild steel ring at flux density of 1.2T and calculate the magnetic field strength to produce a flux of 180 micro webbers in the ring.