Measuring magnetic induction is occasionally performed by our students during their academic training in physics. Among the various methods used to measure it, the Hall effect is the most common and widespread. Another way consists of employing an electronic flux-meter. It is constituted by a small flat coil (SFC) connected to the input of an integrator circuit working with an op amp, whereas the output is connected to a data logger. Then, the SFC is moved perpendicularly to the direction of the magnetic field. Finally, the application of Faraday’s law allows the calculation of the magnetic induction. An electromotive force (EMF) is also induced across the ends of the SFC when it is held stationary in a variable magnetic field. However, this kind of integrator raises numerous problems because the op amp is sensitive to bias and offset currents; both are integrated, leading to the saturation of the output signal.

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.