3. The magnetic circuit of the below figure has cast steel core with dimensions as shown: Mean length from A to B through either outer limb = 0.5m Mean length from A to B through the central limb= 0.2m 2 cm 0.02 cm N 0.02 cm 2 Mean flux path 1x1 cm 0.025 cm ① 1x1 cm In the magnetic circuit shown it is required to establish a flux of 0.75m Wb in the airgap of the central limb. Determine the mmf of the exciting coil if for the core material (a) μ= infinity (b) μ= 5000. Neglect fringing. (20) DONUS QUESTION