An improved apparatus has been developed for demonstrating the hysteresis loops of ferromagnetic materials. Using a Hall probe, a storage oscilloscope, and specially designed circuitry one can in effect plot the initial magnetization curve and the hysteresis loop of a sample point by point, either manually or automatically. Under manual control, the apparatus can also be used to demonstrate minor hysteresis loops of the sample. These minor loops are related to the concepts of permeability μ, incremental permeability μΔand reversible permeability μr.