We reexamine the approximate formula for the path difference in the double-slit interference experiment, establish its limits of applicability from a geometric perspective and discuss its validity for the two-source interference of acoustic and surface waves.

The most important question for anyone born in London is 'Are you a Cockney?' Only those born within the sound of Bow bells can truthfully answer the question with a resounding 'yes.' 'Cockney' is a term of pride in the heart of the East End, an area recently made internationally famous to a new audience due to the global success of the TV series…

The reflection and refraction of light are more familiar to students than the reflection and refraction of sound. Reflection and refraction that occur during the transmission of sound waves are common phenomena in everyday life but are often difficult to understand during actual learning. In this study, we developed a sound reflection and…

Teaching alternating currents, ac or sound waves, is incomplete without an introduction to the oscilloscope. An oscilloscope is a tool that graphically displays electrical signals and shows their time dependence. However, due to the pandemic, triggered by the SARS-CoV-2 virus, many students do not have the opportunity to master the use of an…

The Mayan city of Chichen Itza is full of legends and mysticism. There, in the temple of Kukulkan, in front of a great pyramid with 91 central staircases, an interesting physical-acoustic phenomenon occurs that has fed mythical stories attributed to the Mayas. When clapping your hands in front of the steps, the echo sounds very different from the…

We propose an experiment in which the sound of a drumroll is recorded and analysed according to a simple mechanical model in which the inelastic restitution coefficient of the collision between the stick and drum surface, as well as the ongoing kinematics of the drumstick, are considered. The agreement shows that this model is well suited for…

The udu is a traditional Nigerian percussion instrument that can be thought of as a Helmholtz resonator with two apertures. We use a simple two-particle mechanical analogue to study the behaviour of such a resonator and find that the model describes quite well the main features of udu acoustics.

We present a novel method for demonstrating the physical principles of ultrasound imaging at a level suitable for educational programmes up to the university level, using a simple mechanical model that is very inexpensive and accessible to a broad variety of educational institutions. The method revolves around the use of one or two steel springs…

This work presents two electronic systems experiments with resonance tubes, which generate automatically a sequence of several sound wave frequencies in a range defined by the user and then verifies the amplitude of each one in real-time, allowing for the immediate data visualization in a graph. Besides, they save all the frequency values and the…

We present an experiment designed to study standing waves in a tube with one closed end. Two smartphones are used, one to emit a sound signal with a chosen frequency and another equipped with a microphone to detect the sound pressure level inside the tube. Due to the finite diameter of the tube, the standing wave node (or antinode) appears…

By building a schlieren optical system, the visualization of a 40 KHz sound wave is realized. By using the schlieren system, the demonstration of acoustic reflection, interference and diffraction can be easily realized. At the same time, the visual acoustic field provides another simple way for the measurement of sound velocity. In this paper, the…

In the violin, the fundamental air cavity mode (the A0 mode) is associated with the sound radiated by the f-holes. The dependences of the sound velocity of the A0 frequency on gaseous temperature and mass were investigated. It was found that the frequency of the A0 mode changed, depending on the molecular weight and the temperature of the gas…

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.…

This article presents the study of Fourier series experimentally, using the "ExpEYES"-17 kit in a different way. This familiar undergraduate experiment has been performed for teaching online laboratory classes when face-to-face classes were not possible, due to the "COVID"-19 pandemic. We chose parabolic and sawtooth waveforms,…

This work shows the redesign of an elemental experience based on the Helmholtz resonator using 3D printing. A Helmholtz resonator is based on a volume and at least one opening that can include a tube or not. The air column inside the tube can be considered the mass of the system, whereas the volume represents the system's stiffness. Due to these…