An incandescent lamp filament is focused on a sheet of temperature sensitive, liquid crystal. The liquid crystal sheet indicates that more energy is present below the visible spectrum. Filters that swing into the light path allow the visitor to experiment with the light. The liquid crystal shipped with the exhibit has a sensitive temperature range of 25-30°C. This suits most environments well. If the exhibit is used in a very warm environment, a 30-35°C liquid crystal may be needed instead.