Field and Wave Electromagnetics 2nd Edition by David Cheng

Exercise 28

The total mean length of the flux path in iron for the electromagnet in Figure is 3 (m), and the yoke-bar contact areas measure 0.01 (m 2 ). Assuming the permeability of iron to be 4000µ 0 and each of air gaps to be 2 (mm), calculate the mmf needed to lift a total mass of 100 (kg).