Precision Radiometers

Precision Radiometers


Handmade in Germany

> We offer two Precision Radiometers, a Large and a Giant size. The Large Radiometer is a little over 3" in diameter and about 8.5" tall. The Giant Radiometer is 4.3" in diameter, about 10.5" tall and has a light blue tinted globe. Handcrafted and imported from Germany, the Radiometers completely fabricated by hand. Please note that the measurements are only approximate and will vary a bit from unit to unit. Unlike inexpensive Chinese toy Radiometers, these are highly sensitive and will respond to just the ambient heat & light in a room.



The Solar Radiometer (also known as a Light Mill) is an educational and demonstration device invented by physicist Sir William Crookes in 1873. Crookes thought it was the 'pressure' of the sunlight that made the Radiometer work. Actually, it was the infrared energy in sunlight that made the vanes turn. Inside the Radiometer there are four vanes, each has one blackened side and one silvered side. It is encased in a clear glass bulb at very low air pressure. The different colors on either side of the "vane blades" create the convection currents and that causes the blades to spin when exposed to light or heat. The more intense the light is that shines on it, the faster the vanes inside will turn. With bright light shining on it, the vanes will turn at speeds up to 3,000 RPM.
Select Radiometer size below.

Large Radiometer: $49.00
Giant Radiometer: SOLD OUT