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Question 3 [10 marks] (a) [6 marks] Starting from Ampere's law show that the magnitude of the internal magnetic field intensity of a conductor of radius b due to current / is given by H=1, r≤b 2xb² (b) [4 marks] Draw the magnetic circuit consists of MMFs and reluctances for a device shown in Figure 3. Assume the core is infinitely permeable and the current I, enters the left coil with N, turns whereas current 12 leaves the right coil of N2 turns. The total mean length of the core is l, air gap length is Ig and cross-sectional area of the core is Sc. Leakage in the airgap is negligible and permeability of air is μo. Figure 3 End of the paper (Formula sheet at the back)
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