This demo is used to show the hysteresis curve of iron in a transformer core by plotting B vs H on an oscilloscope. The magnetic induction B is plotted on the vertical axis and the applied field H on the horizontal. The value of H is obtained by using the voltage across a 1 ohm rheostat in series with the primary coil of the transformer. The secondary winding of the transformer picks up the changing flux which is integrated with the 20 microfarad capacitor connected in series with a rheostat set at approximately 2000 ohms. The voltage across the 20 microfarad capacitor is applied to the vertical plates of the oscilloscope. It may be helpful to float the ground lead of the oscilloscope.