Glass Radiometer Product overview A decorative and educational glass radiometer that demonstrates light and thermal movement. The sealed glass globe contains a low friction rotor with four metal vanes, polished or white on one side and black on the other. The interior is close to vacuum, allowing the vanes to respond to light and local heat differences. Under light or infrared radiation the vanes turn one way; under a cold breeze they can rotate in the opposite direction. Key benefits Visual demonstration of thermally driven motion: clearly shows the principle that surfaces that absorb more heat behave differently than reflective surfaces. Stable, all glass construction: transparent glass allows full view of the rotor and vanes while providing a clean, minimal aesthetic. Simple operation: no batteries or power supply required. Rotates under sunlight, incandescent light, infrared sources, or even heat from a nearby hand. Compact display piece: works well on desks, shelves, windowsills, or as a scientific conversation piece. How it works The black side of each vane absorbs heat energy from light and nearby heat sources while the white or polished side releases heat. This temperature difference produces a net force on the rotor and causes the vanes to spin. In cooler airflow conditions the rotor can spin in the opposite direction. Specifications Material: Glass Color: Transparent Size: 120 mm Dial diameter: 75 mm Ball diameter: 90 mm Height: 205 mm Base diameter: 62 mm Alternate base diameter listed: 80 mm Interior condition: Close to vacuum Fins: Polished or white on one side and black on the other Measurement tolerance: +/ 1 to 3 cm Package contents 1 x Radiometer Only the item listed above is included. Other accessories are not included. Suitable uses and placement Educational demonstration: Ideal for classroom demonstrations of thermal effects and simple physics principles. Home or office display: Place near a window or under an incandescent lamp to provide continuous, lowmaintenance motion and visual interest. Gift for curious minds: A distinctive desk ornament for people interested in science, design, or conversation pieces. Notes and handling Operates under direct sunlight, incandescent light, or infrared exposure. Movement may be visible with nearby heat sources such as a warm hand. Handle with care. The product is made entirely of glass and should be placed on a stable surface. Color in photos may vary due to lighting and screen differences. Only the listed package contents are included.