EQUIPMENT
    Radiometer
    Carousel Projector



NARRATIVE
            The radiometer demonstrates that dark-colored dull surfaces are better absorbers of radiation than light-colored sources, shiny surfaces. When light of sufficient intensity strikes the radiometer, the black vanes rotate away from the light. Two effects probably cause this. The blackened sides of the vanes absorb more photons than the silver sides, thereby receiving more energy. This energy is converted to heat which is radiated to the small amount of air in the partially evacuated bulb. This heated air moves away from the blackened vanes causing the vanes to be forced in the opposite direction.