A thin iron ring with mean diameter d=50cm supports a winding consisting of N=800 turns carrying current I=3.0A. The ring has a cross-cut of width b=2.0mm. Neglecting the scattering of the magnetic flux at the gap edges, and using the plot shown in Fig., find the permeability of iron under these conditions.
Where B is in Tesla and H in kA/m. Besides, B and H are interrelated as in the figure shown below of the text. Thus we have to solve for B, H graphically by simultaneously drawing the two curves (the hysterisis curve and the straight line, given above) and find the point of intersection. It is at H≈0.26kA/m, B=1.25T Then μ=μ0HB≈4000.