A closed magnetic circuit of cast steel have a 6cm long path of cross-sectional area 1 cm2 and a 2 cm path of cross-sectional area 0.5cm2.
A coil of 200 turns is wound around the 6cm length of the circuit and a current of 0.4 A flows.
Determine the flux density in the 2cm path, if the relative permeability of the cast steel is 750.