In a ferromagnet, the magnetic induction reaches a saturation value Bs as the magnetic field H increases. The relative permiability µr of the ferromagnet depends on the magnetic field strength H, and also on the previous magnetic treatment of the ferromagnet. Thus, it is common to represent the magnetic induction B in the form of a hysteresis curve as a function of the rising and falling field strength H. The hysteresis curve differs from the magnetization curve, which begins at the origin of the coordinate system and can only be measured for completely demagnetized material.
In the experiment P18.104.22.168, a current I1 in the primary coil of a transformer which increases (or decreases) linearly over time generates the magnetic field strength. The corresponding magnetic induction value B is obtained through integration of the voltage U2 induced in the secondary coil of a transformer. The computer-assisted measurement system CASSY is used to control the current and to record and evaluate the measured values. The aim of the experiment is to determine the relative permeability µr in the magnetization curve and the hysteresis curve as a function of the magnetic field strength H.