Question-I: The core in the magnetic circuit shown in Fig.1 is made up of sheet-steel (c) and cast-steel (cz). It is excited with DC current to produce a flux (,) of 5x10-4 Wb in the air-gap. Data for the B-H characteristic of the two cores is given below in Fig.2. The coil has N = 1000 turns. Also, g = 5 mm The effects of fringing fields at the air-gap and leakage flux are not neglected. a) Calculate the core lengths (1) and (42). b) Calculate the core-sectional areas (A) and (A), as well as gap-sectional area (4). c) Determine the coil current (I). d) Calculate the magnetic stored energy in the air-gap (W). e) The coil is now excited with an AC current of 50 Hz. If the maximum flux produced max = 6 x 10- Wb, find the effective (rms) value of the voltage applied across the coil terminals (Vrms). L-14cm N-1000 4-5pm 9 lux Density, B (Wh/m²) 0.75 05 0.25 " 125 250 Sheet-Steel Cast-Steel 979 850 150 875 10 100 120 Flux intensity, H (A-turn/m) Fig. 1: Magnetic Circuit Fig.2: DC magnetization curve for sheet-steel and cast-steel