Demonstrate thermal radiation from four different surfaces. The aluminium plate heats to a uniform temperature of approximately 70°C or 100°C, depending on the setting.  The four surfaces (black, white, silver, and polished silver) have different thermal emissivities, causing them to radiate different amounts of radiation even though they are all the same temperature.  The photo shows the Leslie’s Cube in visible light on the left and in the infrared on the right.