Visualization of Harmonic Series in Resonance Tubes Using a Smartphone

Because sound waves are such an abstract concept in physics, hands-on activities are often recommended to improve students’ understanding and strengthen their knowledge. However, most schools do not have sufficiently sophisticated measuring instruments to perform sound wave experiments. Recently, researchers used smartphones as oscilloscopes, signal generators, and spectrum analyzers for sound wave experiments. Here we provide a complement to these ideas, developing an affordable smartphone-based sound wave experiment kit to visualize the harmonic series in resonant tubes. It is based on Kundt’s tube, which was originally used to determine the mechanical properties of unknown metal rods and acoustical properties of gases. We also use it to demonstrate the difference in particles’ distribution in harmonic series in both-closed-end, one-closed-end, and both-open-end tubes.