Determining the magnetization of a permanent magnet from static equilibrium

Magnetic material is characterized by its magnetization that indicates the level to which it is magnetized. In this paper, a simple and inexpensive experiment is presented for determining the magnetization of a permanent magnet. It consists of investigating the vertical equilibrium position of a mobile system equipped with a NdFeB magnet as a function of its total mass, and an external magnetic field to which the NdFeB magnet is subjected. The magnetic field is produced by a stack of magnets, which allows to change its magnitude by adding or removing magnet. A model is proposed with a view to interpreting the experimental data. The excellent match between theory and experiment make this a good experiment for the undergraduate student. (paper)