For a number of practical problems, it is important to know not the usual magnetic permeability m=(1/m0)·B/H, but the so-called “differential” magnetic permeability m,=(1/m0)·dB/dH. Here dB/dH is the derivative of the field induction with respect to strength, i.e. the tangent of the tangent angle on the graph is 29.9 a. For practical calculations, we can consider m,=(1/m0)·deltaB/deltaH, where deltaB and deltaH are chosen so small that the plot of the graph can be considered rectilinear. Determine approximately the values of differential permeability for the same values of magnetic field strength as in Problem 29.9. 29.9. The initial magnetization curve of commercially pure iron is shown in Fig. 29.9 a. Using the graph, find the value of the magnetic permeability of this material at magnetic field strengths: 50; 75; 100; 200; 500; 1000; 1500 A/m. Draw a graph of magnetic permeability versus field strength. Using the graph, estimate at what field strength the maximum magnetic permeability (mmax) is achieved and what it is approximately equal to.

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