Radiometer
Originally, designed by William Crooke in the 1860's, the radiometer still fascinates both young and old. Whenever light shines on the four diamond shaped vanes the paddle wheel spins at up to 3,000 rpm. Great for illustrating the conversion of light energy into mechanical energy. Each vane is black on one side and white on the other. Because the black surface absorbs energy better than the white reflective side, the molecules of air move faster near the black surface. Molecules of heated air moving faster on one side of the vain than the other cause it to spin. Explanation and suggested experiments included. Read more on our Blog!