Quantitative analysis of the damping of magnet oscillations by eddy currents in aluminum foil

Muižnieks, A.; Dudareva, Inese

doi:10.1119/1.4725416

Cited by 1 publication

(1 citation statement)

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“…This phenomenon plays a fundamental role in many interesting applications (such as induction furnaces, EM braking, magnetic levitation, evaluation of coating thickness, and so on), as well as in those cases where eddy currents have deleterious effects, such as power loss in a transformer's magnetic core. Due to its importance, this topic has been widely treated in didactical literature [22][23][24][25][26][27][28][29][30][31][32][33], but existing experimental demonstrations present, to our knowledge, some critical issues from a didactical point of view, namely: (i) the underlying physical concept (i.e. the EM induction that is at the origin of the observed dissipative phenomena) tends to be obscured if these experimental demonstrations are mainly focused on the eddy currents (which are only a 'consequence' of EM induction); (ii) the proposed experiments rarely allow learners to perform quantitative determinations [15,16,22,23].…”

Section: Introduction and Pedagogical Contextmentioning

confidence: 99%

An innovative experimental sequence on electromagnetic induction and eddy currents based on video analysis and cheap data acquisition

2017

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In this work, we present a coherent sequence of experiments on electromagnetic (EM) induction and eddy currents, appropriate for university undergraduate students, based on a magnet falling through a drilled aluminum disk. The sequence, leveraging on the didactical interplay between the EM and mechanical aspects of the experiments, allows us to exploit the students’ awareness of mechanics to elicit their comprehension of EM phenomena. The proposed experiments feature two kinds of measurements: (i) kinematic measurements (performed by means of high-speed video analysis) give information on the system’s kinematics and, via appropriate numerical data processing, allow us to get dynamic information, in particular on energy dissipation; (ii) induced electromagnetic field (EMF) measurements (by using a homemade multi-coil sensor connected to a cheap data acquisition system) allow us to quantitatively determine the inductive effects of the moving magnet on its neighborhood. The comparison between experimental results and the predictions from an appropriate theoretical model (of the dissipative coupling between the moving magnet and the conducting disk) offers many educational hints on relevant topics related to EM induction, such as Maxwell’s displacement current, magnetic field flux variation, and the conceptual link between induced EMF and induced currents. Moreover, the didactical activity gives students the opportunity to be trained in video analysis, data acquisition and numerical data processing.

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