Atwood’s Machine and Electromagnetic Induction: A Real Quantitative Experiment to Analyze Students’ Ways of Reasoning

Alberto Stefanel,Marisa Michelini,Assunta Bonanno,Giacomo Bozzo

doi:10.29333/ejmste/11567

Alberto Stefanel, Marisa Michelini + Show 2 more

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https://doi.org/10.29333/ejmste/11567

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Abstract

We report a research-based proposal on electromagnetic induction within the theoretical framework of the Model of Educational Reconstruction. The proposal is based on a sequence of inquiry-based experimental activities centered on hands-on materials and Real-Time quantitative experiments, through which students explore the phenomenology of electromagnetic induction. The sequence was planned to address Faraday-Neumann-Lenz law analyzing the involved physics quantities and constructing quantitative relationships between them. Our hypothesis was based on the idea that phenomenological explorations performed through online sensors promote a functional understanding of electromagnetic induction and help students to face the conceptual knots highlighted by international literature about these phenomena. The educational sequence was proposed to a sample of 87 high school students with the aim of analyzing the evolution of the educational processes employing a set of inquiry-based tutorials. The qualitative analysis of students’ answers demonstrates that students increased their knowledges in the analysis of electromagnetic induction phenomena recognizing the fundamental role of time-variation of the magnetic field flux in the Faraday-Neumann-Lenz law.

Highlights

It is important to build a functional understanding of key concepts related to electromagnetic induction (EMI) (McDermott, 1991; Belcher & Olbert, 2003; Jelicic et al, 2017) that make it possible to describe electromagnetic phenomena and in particular FNL law starting from experimental explorations (Michelini & Vercellati, 2012, 2014a, 2014b; Michelini & Viola, 2008)
We report the analysis of data concerning 87 students of four classes, focusing on: (a) students’ representations of compass-needles in the space around a magnet, (b) qualitative explorations of different situations in which an EMF is induced in a circuit; (c) Real-Time quantitative experiments (RT1 and RT2) performed by means of the electromagnetic Atwood’s machine; (d) individual conclusions given at the end of the sequence and after the last classroom discussion
These descriptions emphasize the produced changes, without highlighting the role of time in the EMI phenomena, confirming a result well known in literature according to which students confuse the variation of a physics quantity with the time variation of that specific physics quantity

Summary

Introduction

Electromagnetic induction (EMI hereafter) plays a crucial role in different physics phenomena (Galili, 2001; Galili & Kaplan, 1997; Kesonen et al, 2011; Scanlon et al, 1969; Zuza et al, 2012) and represents a fundamental prerequisite for understanding many domains of modern physics, as for example superconductivity (Greczyło et al, 2010; Kedzierska et al, 2010) and Special Relativity (Galili & Kaplan, 1997; Galili et al, 2006). It is important to build a functional understanding of key concepts (as for example the concepts of flux and its time variation) related to EMI (McDermott, 1991; Belcher & Olbert, 2003; Jelicic et al, 2017) that make it possible to describe electromagnetic phenomena and in particular FNL law starting from experimental explorations (Michelini & Vercellati, 2012, 2014a, 2014b; Michelini & Viola, 2008)

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