Radiometer, Crookes Style. Glass Construction. A Physical Science Demo of Radiant Energy.

GSC International 7-1113 Radiometer Crookes Style. All Glass Construction.  Glass Bulb with Vanes: A radiometer consists of a glass bulb that contains a partial vacuum. Inside the bulb are four lightweight vanes (or paddles), mounted on a spindle, which can spin freely. Each vane has one side that is black and the other side that is white. Light Energy Conversion: When light shines on the radiometer, the black sides of the vanes absorb more light energy than the white sides. This energy difference causes a temperature gradient, with the black side becoming warmer than the white side. Thermal Transpiration Effect: The warmer black side heats up the surrounding gas molecules inside the radiometer, causing them to move more rapidly compared to the molecules near the cooler white side. This difference in molecular movement creates a pressure imbalance, pushing the vanes to spin. Vacuum's Role in Movement: The bulb is not a perfect vacuum; it contains a very small amount of gas. The pr