Potential difference and current in simple electric circuits: A study of students’ concepts

TLDR

Students generally have difficulty managing simultaneous changes of several variables in electric circuits. The study aimed to identify high school students’ concepts of simple electric circuits. A qualitative diagnostic questionnaire was given to 145 students and 21 teachers to probe their understanding of relationships among circuit variables. Students view current as the primary concept, treat potential difference as a consequence, misuse V=IR, regard batteries as constant current sources, misunderstand emf and internal resistance, and struggle to analyze how changes in one component affect the rest of the circuit.

Abstract

A study which was designed to identify students’ concepts of simple electric circuits is reported. A diagnostic questionnaire was administered to a sample of 145 high school students and 21 physics teachers. The questionnaire included mainly qualitative questions which were designed to examine students’ understanding of the functional relationships between the variables in an electric circuit. The main findings obtained from the analysis of the responses are current is the primary concept used by students, whereas potential difference is regarded as a consequence of current flow, and not as its cause. Consequently students often use V=IR incorrectly. A battery is regarded as a source of constant current. The concepts of emf and internal resistance are not well understood. Students have difficulties in analyzing the effect which a change in one component has on the rest of the circuit. This is probably due to the more general difficulty students have in dealing with a simultaneous change of several variables.