A simple experimental approach to evaluate the stability of foam bubbles using the principle of light refraction in a double cylindrical lens

If an object is placed inside a cylindrical glass vessel filled with water, the image of the object shifts slightly toward the observer, making it appear magnified. This visual phenomenon is mainly caused by refraction of light. Here, we consider a simple experimental setup consisting of two concentric glass vessels used to investigate the behavior of foam bubbles placed inside the inner cylinder while the outer one is filled with water. Due to the cylindrical-lens effect, the observed images of foam bubbles look zoomed, making the investigation of foam properties easy. Furthermore, we present the mathematical model for the object’s location and the magnification factor in detail. Finally, this experiment and mathematical model are not only helpful for undergraduate physics students but also can be extremely helpful for engineering students conducting research on foam stability.