Learning interference between electricity and magnetism? Analysis of patterns and consistency

Abstract

Due to the similarities between Gauss’s and Ampere’s laws, students can present cognitive interference when learning these laws in the introductory physics course. This study aims to analyze the interference patterns that emerge in students’ answers when solving problems that involve Gauss’s and Ampere’s laws and related concepts (e.g., electric flux and magnetic circulation). We conducted a study of 322 engineering students attending a private Mexican university. We applied two open-ended questionnaires with questions that prompted using Gauss’s and Ampere’s laws. We analyzed students’ answers to identify whether they presented some word or element of an equation from the opposite context and coded them into coding families. We analyzed the consistency of interference by counting the times each student presented some interference in general and by coding family. The results indicated that the interferences related to the shape of the Gaussian surface or Amperian trajectory and field-related concepts are shared among contexts. However, the interference related to the source of the field (charge or current) is predominant in magnetism. In contrast, the interference related to using elements from the opposite context in an equation predominates in electricity. In other words, students referred to currents as charges and wrote equations that contained B (for magnetic field) or other similar elements in Gauss’s law. The general consistency analysis revealed that around half the students presented at least one interference in both contexts. We recommend that the interference between electricity and magnetism in Gauss’s and Ampere’s laws must not be overlooked. This study’s findings can guide introductory and intermediate electricity and magnetism instructors to address this interference phenomenon.