This solar radiometer is great for demonstrating the power in sunlight. Place it in a window and watch it go!
Experience this sphere powered by the sun! The vanes in the Radiometer are alternately dark and light in colour. When the light strikes these vanes it transfers heat to each one - but not at the same degree. The lighter vane reflects the rays and the darker vane absorbs the rays. The stronger the light, the more energy there is causing the vanes to spin faster..