If the gap field is B then the H-field in the gap is H g = B/µ 0 . The permeability of free space, µ 0 = 4\(\pi\) × 10 −7 , is a small number therefore H g will be quite large: if B=1.0 Tesla then H g...If the gap field is B then the H-field in the gap is H g = B/µ 0 . The permeability of free space, µ 0 = 4\(\pi\) × 10 −7 , is a small number therefore H g will be quite large: if B=1.0 Tesla then H g = 7.96×10 5 Amps/m. The integral of the current density over the area bounded by the magnet center line is just NI so that the line integral of H becomes where L is the length of the path in the ferromagnetic yoke and g is the width of the gap.
