A new implementation of Kundt’s tube: 3D-printed low-cost set-up using ultrasonic speakers.

Haverkamp, Nils; Havemann, Judith; Holz, Christoph; Ubben, Malte; Schlummer, Paul; Pusch, Alexander

Abstract

Kundt’s tube is a popular experiment commonly used in schools, in which standing sound waves are made visible inside a glass tube. A fine powder is stirred up in areas of high sound particle velocities, so that one can measure the wavelength of the sound waves by examining the patterns created. In this way, the ‘invisible’ can be made visible. However, when looking at educational contexts, Kundt’s tube is an experiment with several shortcomings—despite its popularity and prevalence: The glass tube is big, expensive and fragile. Additionally, during the experiment itself, the sound tends to be quite loud due to the high sound pressure needed so that communicating during the experiment becomes hard or even impossible. In this article, we propose a silent and low-cost alternative to commonly used setups which can easily be constructed by using 3D-printed parts as well as readily available ultrasonic transmitters. This makes Kundt’s tube even implementable as an experiment done by students themselves.