Using a PC and external media to quantitatively investigate electromagnetic induction

In this article we describe an experimental learning path aboutelectromagnetic induction which uses an Atwood machine where one of thetwo hanging bodies is a cylindrical magnet falling through a plexiglass guide,surrounded either by a coil or by a copper pipe. The first configuration(magnet falling across a coil) allows students to quantitatively study theFaraday–Neumann–Lenz law, while the second configuration (falling througha copper pipe) permits learners to investigate the complex phenomena ofinduction by quantifying the amount of electric power dissipated through thepipe as a result of Foucault eddy currents, when the magnet travels throughthe pipe. The magnet’s fall acceleration can be set by adjusting thecounterweight of the Atwood machine so that both the kinematic quantitiesassociated with it and the electromotive force induced within the coil arecontinuously and quantitatively monitored (respectively, by a commonpersonal computer (PC) equipped with a webcam and by freely availablesoftware that makes it possible to use the audio card to convert the PC into anoscilloscope). Measurements carried out when the various experimentalparameters are changed provide a useful framework for a thoroughunderstanding and clarification of the conceptual nodes related toelectromagnetic induction. The proposed learning path is under evaluation invarious high schools participating in the project ‘Lauree Scientifiche’promoted by the Italian Department of Education