Using an Infrared Camera to Visualize a Simple Demonstration of Changing the Internal Energy of a System

A novel demonstration device for realizing the intuitive visual observation of the system's internal energy change is proposed. The device is safe, simple, and efficient, combining an infrared camera with a water bottle sprayer. With this setup, the changes of thermal images for air and helium during the compression and expansion processes were studied, respectively, and the temperature-dependent behavior of gas density was revealed.