Verifying Ohm’s Law: A Portable and Innovative Method Using Two Smartphones

Abstract

Abstract

We present a portable, cost-effective, and innovative method for experimentally verifying Ohm’s law in alternating current (AC) resistive circuits using two smartphones: one functions as a signal generator (audio output) and the other as an oscilloscope (microphone input). By connecting identical resistors in series, we systematically increase the total resistance and measure the voltage across a fixed reference resistor. Our results reveal an inverse relationship between the reference voltage and the total resistance, in agreement with Ohm’s law. Fitting the data to a power law yields an exponent of -1.004, which deviates by only 0.4% from the theoretical value of -1. The proportionality constant obtained differs by only 0.7% from the value calculated directly from the measurements. These minimal discrepancies, achieved using non-traditional, uncalibrated equipment and commercial resistors, demonstrate that our methodology is accessible, reproducible, and accurate. This approach validates Ohm’s law with high precision and underscores the potential of mobile devices as reliable experimental tools for physics education, particularly in unconventional or remote laboratory environments.