Working point (operating point) is a point, where the working line (load line) intersects the magnet's B-H demagnetization curve, and indicates the B and H state of the magnet in the magnetic circuit. Knowing the working point is essentia lasit makes possible to forecast the magnetic flux density Bd that can be taken out from the magnetic circuit and whether or not the magnet itself is in risk to be demagnetized. The slope of the load line is expressed as B/H = μ Pc, and Pc is called the permeance coefficient.
Permeance coefficient can be approximately calculated for simple shapes like, cylinder and rectancular block. In the case of magnetic circuits with ferromagnetic parts, FEM modelling is recommended. It is also to be noted that