Faraday’s Law of Induction by Experiment

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.