Here's how it works:
* The Setup: A light mill consists of a set of vanes, usually made of thin, lightweight material, mounted on a central shaft. These vanes are often black on one side and white or shiny on the other. The entire assembly is placed inside a glass bulb with most of the air evacuated.
* The Physics: When light shines on the vanes, the black side absorbs more light energy than the white side. This absorbed energy is transferred to the molecules of the air near the vanes, causing them to move faster. The faster-moving molecules collide with the black side more forcefully than the white side, creating a pressure difference. This pressure difference pushes the vanes, causing the light mill to spin.
* The Effect: The spinning speed of the light mill depends on the intensity of the light. Brighter light creates more pressure difference and faster spinning.
It's important to note that light mills don't directly convert light into mechanical energy. They actually use the energy of the light to heat the air molecules, which then drive the rotation.
