Some Student Conceptions of Electromagnetic Induction

Abstract

Introductory electromagnetism is a central part of undergraduate physics. Although there has been some research into student conceptions of electromagnetism, studies have been sparse and separated. This study sought to explore second year physics students' conceptions of electromagnetism, to investigate to what extent the results from the present study are similar to these results from other studies, and to uncover any new forms of alternative conceptions. Data for this study came from 15 in-depth interviews. Three previously unreported alternative conceptions were identified in the study: 1) induced current varies proportionately with current in solenoid; 2) there must be contact between magnetic flux and the external coil in order for any emf to be induced in the coil; 3) coulombic or electrostatic potential difference is present in an induced electric field. These alternative conceptions were manifested in these students' explanations of electromagnetic phenomena presented to them during the interviews.

Addressing students’ difficulties with Faraday’s law: A guided problem solving approach

“…Tilley presents an example featuring a wide flux variation through the circuit but no induced electromotive force is produced. The author states that this example shows that Faraday's "flux rule" has exceptions as already shown in the examples proposed by Feynman [2] (p. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

“…A significant number use explanations based on transmitting a "force" or "contact with the field." Most students do not distinguish between the empirical level (voltmeter and ammeter measurements) and the interpretative level that uses concepts such as fields and electromotive force [13,14]. (b) Many students interpret that the magnetic field produces electromagnetic induction [15,16].…”

“…(c) Many students understand magnetic flux as "flowing" from the field or they confuse it with the field itself. Most university students use Faraday's law without any physical meaning [13,14,[17][18][19]. (d) When students apply Faraday's law, most of them tend to confuse the circuit area with the integration area in Faraday's law [10,11,15].…”

“…(d) When students apply Faraday's law, most of them tend to confuse the circuit area with the integration area in Faraday's law [10,11,15]. (e) Many students are not capable of recognizing electromagnetic induction when there is no induced current [14,16]. (f) Students have a major tendency to explain induction phenomena using a field model, even in situations where reasoning based on Lorentz's force considerably facilitates induction analysis.…”

“…Students must have basic familiarization with EMI phenomena [13][14][15]. So, before the study of a quantitative interpretation of EMI phenomena, students worked on a task where they analyzed that electromagnetic induction is a phenomenon associated with two different facts: time variation of a magnetic field or the movement of a conductor in a magnetic field or a combination of the two.…”