To convert radiating energy into kinetic energy. Winged cross with 4 mica plates blackened on one side. On a rotating shaft in an evaluated glass vessel.
Features
Partial vacuum: The glass bulb is sealed and contains a partial vacuum, meaning most of the air has been removed. This is crucial because the device's movement is caused by gas molecules, not a complete vacuum. Light-sensitive vanes: Inside the bulb is a low-friction rotor with four thin vanes, each painted black on one side and white on the other.
Rotary motion: When light shines on the vanes, they rotate. The black sides absorb more light and heat up faster than the reflective white sides. Thermal transpiration: The heating of the black sides causes a pressure difference. Gas molecules are more energetic on the hot (black) side and create a force that pushes the vanes forward. The black sides are pushed backward, causing the rotor to spin with the white sides leading the rotation. Speed is proportional to light: The more intense the light source, the more heat is generated, and the faster the vanes will spin.
Optimal pressure: The device works best at a specific pressure, which is not a perfect vacuum or atmospheric pressure. The optimal pressure is where the mean free path of the gas molecules is roughly the same as the width of the vanes.