A number of articles in this journal’s “iPhysicsLabs” column have demonstrated that smartphones and tablets can help bring technologies to the classroom in an inexpensive way, e.g., acceleration sensors1 or diverse applications of video analysis.2 Whereas those articles featured mostly quantitative experiments, we will demonstrate in this article how smartphone thermal cameras can be used to tackle a common problem in energy instruction with a simple qualitative experiment. Lately, thermal imaging cameras for smartphones have become available. Thermal imaging cameras use imaging sensors that are sensitive in the long-wave infrared (8 to 14 µ while visible light ranges from 0.4 to 0.8 µ). The resulting image is a false color image where different colors are used to represent different temperatures (Fig. 1).
Energy is often introduced as the ability to cause change,3 and if a system undergoes changes, those changes are evidence for energy transfers...