The Cable to the Moon: Veritasium's Light Bulb Experiment in Low-Cost Miniature Form

Abstract

In a popular YouTube video by the channel Veritasium, the following question is posed: Imagine you have a giant circuit consisting of a battery, a switch, a light bulb, and two wires which are each 300,000 km long. That is the distance that light travels in one second. So, they [the wires] would reach out halfway to the Moon and then come back to be connected to the light bulb, which is one meter away. Now the question is: After I close this switch, how long would it take for the light bulb to light up: Is it half a second, one second, two seconds, 1m/c or none of the above? As part of the Physics Specialist Camp 2022 in Seifhennersdorf -- a final event of the Saxon Physics Olympiad -- students from grades 9 and 10 built a miniature model consisting of a printed circuit board and two 10-meter cables to experimentally study the question. This article describes the experimental setup, presents some exemplary results, and explains them in detail. To enable reconstruction for educational purposes, the final PCB layout, as well as the supply sources and design considerations, are provided.