A Look into Students' Interpretation of Electric Field Lines

Abstract

On Electricity & Magnetism (EM) courses at undergraduate level, the concept of electric field poses one of the most relevant and basic topics, along with the concept of magnetic field. Professors and students may use different diagrams as a tool to visualize the electric field, such as vectors or electric field lines. The present study aims to identify how students interpret and use electric field lines as a tool or resource to describe the electric field. Two versions of a test with open-ended questions were administered in Spanish in a private Mexican university to a random sample of students taking the EM course, and were analyzed with a qualitative approach. It was found that students do not interpret electric field lines diagrams correctly, which may lead to misconceptions. Many students based their answers on the concepts of superposition, force and repulsion.

Exploring instructors’ interpretation of electric field lines

“…Törnkvist et al observed that some students tried to identify a source of field in diagrams where they did not include charges [2]. In diagrams where the charges are present, students can more readily apply the principle of superposition, compared to diagrams without the charges [6].…”

“…It is interesting to observe this behavior in instructors, as students have shown similar patterns. Students often need to identify the sources of field before making a deeper interpretation [6]. Törnkvist et al observed that some students tried to identify a source of field in diagrams where they did not include charges [2].…”

“…They treat electric field lines as real [2] and as material entities that transport charge [3], confusing electric field lines with trajectories [4]. Students have difficulties finding information about the magnitude of the electric field in electric field lines diagrams [5], applying the principle of superposition and associating the density of lines with the relative magnitude of the field [6].…”

Students’ conversion from electric field line diagrams to other representations

“…The literature also reports students' difficulties interpreting the magnitude and direction of the electric field in the electric field lines diagram. Students have difficulties relating the magnitude of the field and the diagram of electric field lines [12], and they fail to interpret the density of lines as the relative magnitude of the electric field [7,13]. Some students confuse the curvature of the field lines with the direction of the electric field [10].…”

“…Some students confuse the curvature of the field lines with the direction of the electric field [10]. It has also been found that some features of the diagram may create a blocking effect on the correct application of the superposition principle of electric field [13,14].…”