A sensor-based study of the candle-under-glass experiment

This paper presents an innovative approach to the classic ‘candle under glass’ experiment. While often chosen for its simplicity and ability to spark curiosity, the experiment can reinforce common misconceptions, as its full explanation is rarely fully understood. To address this, we investigate the process in stages, measuring key physical quantities to reconstruct the temporal sequence leading to pressure reduction. Used in this emblematic way, the experiment provides original insights that support more effective science teaching. By integrating low-cost Arduino-powered sensors and data acquisition systems, we move from a qualitative to a quantitative analysis, obtaining a detailed mapping of key variables governing the phenomenon. This approach highlights the roles of thermal expansion and contraction, gas consumption, and water vapor condensation, while providing real-time data that deepens understanding of fundamental concepts such as the ideal gas law, partial pressures, and vapor pressure. The methodology aligns with inquiry-based learning and promotes the development of critical thinking by seamlessly connecting theory with observation. The experiment’s simplicity and use of common materials make it a versatile and powerful tool for STEM education.