Discharging a capacitor

Abstract

Discharging a capacitor is a standard experiment in physics education. Here it is described in a form that challenges students’ preconceptions, since the voltage across the capacitor is observed to oscillate after switching off the power supply. The aim is to demonstrate the importance and relevance of experiments and measurements, even if these are in contradiction with expectations and textbooks. Students have the opportunity to develop a quantitative model for the observations and explore the transition from oscillatory to overdamped behaviour—with the latter being the standard in textbook presentations—in further measurements. The experiment can also be used in schools, since the concept of tuning the damping by resistance variation is rather intuitive and insightful even without a formal mathematical background.