2025 Volume 66 Issue 1 Pages 155-161
Conductance is a concept that describes the ease of current flow and is expressed as the reciprocal of resistance. In the “Properties of Electric Current” section of the second-year lower secondary school study unit on the “Relationship between Voltage and Current,” conductance was used as a proportional constant in the equation relating voltage and current. As a result, it was reported that Ohm’s law was easier to understand because it can be expressed in the form of the basic proportional equation students learned in mathematics (Fukuta & Tonishi, 2021). As an extension, this study deepened students’ understanding of the concept of conductance (G) by applying it to the study of “Combined resistance,” particularly the parallel connections of resistors. The students were able to intuitively understand that series connections of resistors add resistance (R=R1+R2) and parallel connections of resistors add conductance (G=G1+G2). Based on the students’ ideas, experiments were conducted to confirm these relationships. The students had previously learned that conductance and resistance are interchangeable (G=1/R), so they could easily replace “G=G1+G2” with “1/R=1/R1+1/R2.”
In general, students try to memorize the formula for connecting resistors in parallel “1/R=1/R1+1/R2” because they lack semantic understanding. However, with the introduction of the concept of conductance and the understanding that conductance is additive in parallel connections, the equation “1/R=1/R1+1/R2” could be more fully understood by the students as a meaningful proposition.
