Smartphone-based approach to demonstrating relativistic aberration of light using electronic circuit analogues for undergraduates in the Philippines

Abstract

Previously, we demonstrated an electronic circuit analogue of one of Special Relativity's (SR) phenomena called the Relativistic Aberration of Light (RAL) (European Journal of Physics, 42, 015605, 2021), which describes the change in the angle an observer sees a light source relative to their direction of motion at relativistic speeds. It used typical bulky laboratory equipment such as (i) function generators, (ii) oscilloscopes, and (iii) power supplies together with our all-pass filter (APF)-based electronic circuit analogue to perform experiments.In this paper, we present a novel smartphone-based experimental set-up performing the same experiment, but we replace the bulky and expensive laboratory equipment with a low-cost and compact smartphone system that can function as both function generator and oscilloscope. Our smartphone system consists of (i) an Android 8.0 (Oreo) application and (ii) an ESP32-based external module that may be wired or wirelessly interfaced for oscilloscope and signal generation functions.The setup was able to carry out the experiment, however the sampling rate was only limited to 8.5kHz, but with the added input channel, phase shift calculation was much more consistent, albeit with a slight offset of -15 degrees due to the added buffer circuit between the ESP32 and APF circuit. We hope that through our work, we expand the toolset of physics educators and researchers, particularly those in developing countries, especially with our system's considerations of equipment accessibility, affordability, and simplicity.