The observed losses in a ferromagnetic core are always greater than those calculated on the basis of a homogeneous permeability. In a magnetization process by domain‐boundary displacements the permeability is certainly not homogeneous, but attains extreme values in the domain walls. As a result of this concentration of the changes in magnetic flux the dispersion curves of the initial permeability as a function of frequency show a shift of the dispersion region towards lower frequencies with increasing domain size. This is the well‐known eddy‐current anomaly encountered in laminated cores. An electric‐circuit model was utilized to determine the eddy‐current distribution and domain‐boundary motion in a number of idealized cases.