Imaging and Studying Standing Waves with a Homemade Melde-type Apparatus and Information and Communication Technology (ICT)

Wave physics phenomena can be observed in everyday life and represent a fundamental prerequisite to many domains of classical and modern physics. Lots of studies demonstrate that novices have to face important learning difficulties in approaching this topic. The study of string vibrations’ modes allows an educational introduction to basic concepts, but common laboratory approaches employ dedicated experimental setups usually requiring some expensive components (wave or vibration generators, motion detectors) that often are not present in school laboratories. The problem of low-cost solutions for the Melde apparatus has been addressed many years ago. Some recent papers propose low-cost solutions in which standing waves on a Slinky spring obtained with non-reproducible hand movements are analyzed by means of video analysis software. In this context, we projected a modern revisitation of the historical experiment proposed for the first time by Melde in 1859, employing low-cost materials and commonly used information and communication technology (ICT) devices in order to generate and analyze standing waves on a string (see next section). This experimental setup was proposed to a group of 26 students (17–18 years old) in the fourth year of an Italian high school. Students were involved in four sessions (about four hours each) of inquiry-based laboratorial activities, in which they recorded various standing wave configurations on a string with their smartphones and analyzed the obtained videos using the freeware Tracker®, whose potential value is well known in literature. The experimental setup is described and an example of data analysis and obtained results is shown. Finally, students were asked to develop their own Melde-type apparatus; in the last section we present a very interesting alternative solution developed by a group of them, which offers almost the same educational features on a reduced scale using even simpler components.