The Fig. P1.1 shows a cross-section of the magnetic structure of a four-pole DC machine. On each of the four stator poles, there is a coil with equal turns. The four coils are connected in series and carry the same current. The stator poles and yoke are made of laminations of cast steel sheets, while the rotor yoke is made up of silicon steel. The B-H curves for cast steel and silicon steel are shown in Fig. P1.2. The DC machine has the following dimensions: Each pole (cast steel): magnetic length = 10 cm; cross-section = 400 cm^2 Each air gap: length = 0.1 cm; cross-section = 400 cm^2 Rotor Yoke (silicon steel): average length = 20 cm; average cross-section = 400 cm^2 Stator Yoke (cast steel): mean circumference = 160 cm; average cross-section = 200 cm^2 The flux supplied by each pole is the same (quarter of the exciting ampere-turns are placed on each of the four poles). (a) Draw the magnetic equivalent circuit in terms of the N, I, ip, ig, ip, and is. Label and show all the flux directions in all sections. The s are reluctances. (b) Determine the mmf produced per pole required to produce a flux density of 1.1 T in the magnetic circuit (c) Determine the rotor flux.