Planetas, ¿por qué se mueven?

Premio extraordinario de Trabajo Fin de Máster curso 2020/2021. Máster en Profesorado de Enseñanza Secundaria Obligatoria, Bachillerato, Formación Profesional y Enseñanza de Idioma

Measuring capacitor charge and discharge using an LED and a smartphone

The research leading to these results has received funding from the fellowship FPU17/02191 and FPU20/02835, projects Ref. PID2020-113681GB-I00, Ref. PID2021-128970OA-I0 from the Spanish Ministry and Agencia Estatal de Investigación (AEI) and from FEDER/Junta de Andalucía programs A.FQM.752.UGR20 and P20 00173. The authors would like to thank F. de los Santos and A. Ortiz-Mora for their advice and insightful comments.In this article, we present a simple, inexpensive, and effective method for measuring the capac- itor charge and discharge processes using a Light Emitting Diode (LED) and the light meter of a smartphone. We propose a simple circuit in which the LED’s brightness is linear on the capacitor’s voltage, allowing us to use the smartphone to monitor the capacitor state accurately. The method is tested experimentally, giving highly satisfactory results. Its exceptional combination of accuracy, minimal requirements, and ease of setup makes it an excellent way to introduce undergraduate students to the concepts of electricity and electronics in any educational setting.Spanish MinistryAgencia Estatal de Investigación (AEI): FPU17/02191, FPU20/02835, PID2020-113681GB-I00, PID2021-128970OA-I0FEDER/Junta de Andalucía programs AFQM.752.UGR20, P20_0017