A section through a magnetic circuit of uniform cross-sectional area 2 cm² is shown in Figure 5. The cast steel core has a mean length of 25 cm. The air gap is 1 mm wide and the coil has 5000 turns. The B-H curve for cast steel is shown on Figure 2. Determine the current in the coil to produce a flux density of 0.80 T in the air gap, assuming that all the flux passes through both parts of the magnetic circuit. Air gap 25cm Figure 5 5000 Burs [0.152 A] Given a magnetic circuit as shown in Figure 6 where its core is cast steel. The B-H curve for cast steel is shown on Figure 2. The centre limb has a cross-sectional area of 800mm² and each of the side limbs has a cross sectional area of 500mm². A coil of 400 turns is wound on the centre limb. Neglect any magnetic leakage and fringing effect. Determine the m.m.f. and current required to establish a flux of 1.048 x 10°³ Wb in the centre limb. 340mm Figure 6 1mm -150mm 340mm B (T) 1.6 1.4 1.2 1.0 ±22% 0.8 0.6 0.4 0.2 NT Sheet steel Cast steel Cast iron 0 500 1000 H (At/m) 1500 2000 2500 3000 3500 4000 4500 5000 Figure 2