The Classic Sphere Powered by the Sun!
Set our radiometer (also known as a light mill) in the sun, or bright light, and watch the vanes spin! More light, more spin!
How does it work? The vanes, or wings, in the Radiometer are alternately dark and light in color and set on a spindle in a near vacuum. When the light strikes these wings, it transfers heat to each one - but not to the same degree. The lighter wing reflects the rays, and the dark wing absorbs the rays. This difference causes the big spin!
- When the freely moving particles of air inside the radiometer strike the light-colored reflective vanes, they take on very little energy and do not bounce off very fast.
- When the atoms strike the dark vanes, they take on a great deal of energy...and "kick" away at terrific speed.
- Result: The vane begins to spin and continues to spin as the bits of air continue to "kick" away from the dark-sided vane.
- Tthe stronger the light, the more energy there is to "heat up" the dark side of the wing...causing the vanes to spin faster and faster as the light gets brighter.
- What FUN!