A shunt-field dc machine has a field winding with Nf = 280 turns, all in series and wound on four poles. Each pole then has the same turns Nf/4. The winding has a current of If = 50.0 A. Each field pole has dimensions of 200 mm and 250 m. The air-gap length g = 5.00 mm. Calculate the magnetic field intensity H (hint: use Ampere's law), the flux density B, and the flux per pole f. Use the correct SI unit for each quantity. The iron parts have a permeability that is about 4000 fo, so the iron may be neglected in Ampere's law. Assume the flux under each field pole is uniformly distributed.