A mild steel ring has a radius of 50mm and a cross-sectional area of 400mm2.
A current of 0.5 A flows in a coil wound uniformly around the ring and the flux formed is 0.1mWb.
If the relative permeability at this value of current is 200 find
(a) The reluctance of the mild steel and
(b) The number of turns on the coil.