Estimation of nanometer-thickness layer of 6B graphite: an experimental activity to study Ohm’s law in higher education

Abstract

Ohm’s Law is essential for understanding electrical circuits and conductive materials. Formulated by Georg Simon Ohm in the 19th century, it describes the direct proportional relationship between electric voltage and current in ohmic conductors. Despite its apparent simplicity, studies show that students at different educational levels struggle to understand it, mainly due to the abstraction of voltage, current, and resistance concepts. To help overcome these difficulties, this work proposes an experimental activity that applies Ohm’s Law to determine the nanometer-scale thickness of 6B graphite traces deposited on tracing paper. The methodology involves measuring voltage, current, and length, followed by data analysis. The thickness obtained through this approach was compared with results from a Scanning Probe Microscope (SPM). Based on the proposed method, the graphite trace thickness was determined as 456.5(34) nm, while SPM measurements yielded an average thickness of 440(50) nm. The results show good agreement within experimental uncertainties, validating the method’s effectiveness. Therefore, the proposed activity represents a feasible and low-cost alternative for applying Ohm’s Law in undergraduate Electricity courses and, with adaptations, even in high school, helping students connect theoretical concepts with experimental practice.