When I was a kid, one of my neighbors had a solar radiometer. It’s a glass bulb about the size of a baseball, with diamond-shaped panels connected to a spindle. The panels, black on one side and silver on the other, would turn on the spindle when exposed to light.
I enjoyed experimenting with the gizmo, edging it in and out of the sunbeam that shone through a window and onto their kitchen table. How close to the light did the radiometer need to be for the panels to move? What if I shaded it with a piece of cardboard? How fast would the spindle turn if I put the radiometer fully in the light? Read More »