Crookes Radiometer STEM Lab
Product Code : SCL-MH-12497
Quick Answer: The Crookes Radiometer STEM Lab is a light mill: 4 mica vanes, silvered on one face and black on the other, spin on a steel pivot inside a partly evacuated borosilicate glass bulb when light falls on them. The bulb is 15.0 cm high with a 7.5 cm sphere, held on a cast iron base, and a 10W halogen spotlight is included.
Last updated: October 2026
Key Features
- Borosilicate glass bulb, 15.0 cm high, 7.5 cm sphere diameter
- 4 mica vanes on a low-friction steel pivot pin
- Reflective silver coating on one face, matte carbon black on the other
- Powder-coated cast iron base with a vertical clamping post
- Variable-intensity 10W halogen desk spotlight included
Technical Specifications
| Specification | Value |
|---|---|
| Bulb | Borosilicate glass, partial vacuum |
| Bulb size | 15.0 cm height, 7.5 cm sphere diameter |
| Vanes | 4 mica panels on steel pivot pin |
| Vane faces | Silver (front), carbon black (back) |
| Base | Powder-coated cast iron with clamping post |
| Light source | 10W halogen spotlight, variable intensity |
About This Product
With the vanes first at rest, the spotlight is set 15–20 cm from the bulb on its lowest setting and turned up gradually; the vanes start to turn with their black faces moving away from the light. The apparatus is used to discuss how absorbed radiation warms the dark faces, how the thin gas left in the bulb pushes at the vane edges, and why the effect depends on the bulb being only partly evacuated. Educational Instrument can arrange export supply of the Crookes Radiometer STEM Lab to Tanzania, Malta, Slovenia, Kenya and Barbados.
Frequently Asked Questions
Which way do the vanes of the Crookes Radiometer STEM Lab turn?
The matte black faces move away from the light source as the vanes spin.
Is a light source supplied?
Yes. A variable-intensity 10W halogen desk spotlight is included.
Related: Mechanics & Heat and Thermocouple Electricity Generator STEM Lab.
For a quotation on the Crookes Radiometer STEM Lab, contact Educational Instrument.
