Visualizing the Beat Phenomenon Between Two Amplitude-Modulated Light Beams on a Solar Cell Using Smartphones

The beat phenomenon arises when two harmonic oscillations of slightly different frequencies (f1 and f2) are superimposed. This phenomenon has been extensively exemplified in physics teaching journals for different contexts. For instance, acoustic beats between sound waves have been studied with tuning forks, conventional speakers and microphones, and more recently, smartphones. Likewise, mechanical beats have been studied using a spring-mass system or a pendulum. The beat can also be visualized on an oscilloscope screen by superimposing electrical signals. In relation to light waves, there are also reported works in the literature. More exotic cases include the “beating” phenomenon in the oscillation of the synodic period of the Moon or the beats displayed with foam packing.