Prob.1- A rectangular magnetic core shown in the below Fig. has square cross-section of area 16 cm². An air-gap of 2 mm is cut across one of its limbs. Find the exciting current needed in the coil having 1000 turns wound on the core to create an air-gap flux of 4 m Wb. The relative permeability of the core is 2000. N=1000 2 mm. 20 cm