A mild steel ring of 30 cm mean circumference has a cross-sectional area of 6 cm2 and has a winding of 500 turns on it. The ring is cut through at a point so as to provide an airgap of 1 mm in the magnetic circuit. It is found that a current of 4 A in the winding, produces a flux density of 1 T in the air-gap. Find (i) the relative permeability of the mild steel and (ii) inductance of the winding