A toroid is constructed of a magnetic material having a cross-sectional area of 2.5 cm² and an effective length of 8 cm. There is also a short air gap of 0.25 mm length and an effective area of 2.8 cm². An mmf of 200 A· t is applied to the magnetic circuit. Calculate the total flux in the toroid if the magnetic material:

(a) Is assumed to have infinite permeability;

(b) Is assumed to be linear with μ_r = 1000;

(c) Is silicon steel.