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Crookes Radiometer
Crookes Radiometer (Product Code: SCI-319/013) is a partly evacuated glass bulb containing a light-driven rotor, used to demonstrate how radiant energy can be turned into motion in school and college physics classes. Its four mica vanes, each matt black on one side and white on the other, spin when sunlight or a bright incandescent lamp falls on the 80 mm bulb. It is made by Jain Scientific Equipments Pvt Ltd (ScienceLab), an OEM manufacturer, at its own factory in Ambala, India.
Specifications
| Parameter | Detail |
|---|---|
| Bulb | Partly exhausted glass bulb, 80 mm diameter |
| Rotor | Delicately balanced, carrying a set of four mica vanes |
| Vane size | 5 mm square |
| Vane finish | One side matt black, the other side white |
| Light needed | Sunlight or a sufficiently bright incandescent light source |
| Behaviour | Vanes rotate with the white faces in front; very rapid rotation in direct sunlight |
| Overall height | 125 mm |
| Product code | SCI-319/013 |
| Manufacturer | Jain Scientific Equipments Pvt Ltd (ScienceLab) — OEM |
| Country of origin | India (made in Ambala, Haryana) |
What Is a Crookes Radiometer Used For?
The Crookes radiometer is a classic demonstration model for the physics lab, used when teaching thermal radiation, absorption by dark and light surfaces, and the kinetic theory of gases. The blackened face of each vane absorbs more energy and warms slightly, and air molecules rebounding from the warmer side give it a little extra push, so the rotor turns with its white faces in front.
Show students how the speed changes as the lamp moves closer or further away, or when a sheet of card shades the bulb. The direction of spin is itself a lesson: pure light pressure would push the reflective white faces hardest, so the observed rotation points to a thermal effect of the remaining gas. Handle the bulb gently and keep it upright, because the rotor is delicately balanced.
OEM Manufacturer
ScienceLab is the trading name of Jain Scientific Equipments Private Limited (CIN U29309HR2020PTC087597), the OEM (original equipment manufacturer) of this Crookes Radiometer. It is produced at the company's licensed factory at 449, HSIIDC Industrial Area, Saha, Ambala, Haryana (Factory Licence AMB-ONLINE-CHD-J-414), and dispatched factory-direct to schools, colleges, science centres, dealers and importers. Replacement units after breakage and repeat orders are handled by the manufacturer itself, so simply ask us. Company background is on our profile page.
Related Laboratory Equipment
Apparatus for the same unit on heat and radiation:
- Leslie Cube — compares radiation emitted by black, white and shiny surfaces.
- Radiation Can Set — shows how surface colour affects heating and cooling.
- Heat Absorption & Radiation Comparator — measures absorption differences between surfaces.
- Lamp Holder — for mounting an incandescent lamp as the light source.
Visit the Laboratory Equipment category for more physics demonstration apparatus.
Frequently Asked Questions
Why does the Crookes Radiometer spin?
The Crookes Radiometer spins because the matt black side of each mica vane absorbs more radiant energy and becomes warmer than the white side. Air molecules striking the warmer black faces give a slightly greater push, so the rotor turns with its white faces in front.
What light source does the Crookes Radiometer need?
The Crookes Radiometer needs sunlight or a sufficiently bright incandescent light source. In direct sunlight the vanes rotate very rapidly; indoors, a bright incandescent lamp placed close to the 80 mm bulb gives a clear classroom demonstration.
How big is the Crookes Radiometer?
The Crookes Radiometer has an 80 mm diameter glass bulb and an overall height of 125 mm, with four mica vanes each 5 mm square, so it fits easily on a demonstration bench or a student table.
Does the Crookes Radiometer prove that light exerts pressure?
No. If light pressure drove the Crookes Radiometer, the reflective white faces would be pushed hardest and the black faces would move in front. The observed rotation, white faces first, shows a thermal effect of gas molecules in the partly exhausted bulb.
Who manufactures the Crookes Radiometer?
Jain Scientific Equipments Pvt Ltd (ScienceLab) is the OEM manufacturer of the Crookes Radiometer, producing it at its licensed factory at Saha, Ambala, Haryana, India, and supplying it direct to schools, colleges, dealers and importers.
How should the Crookes Radiometer be handled and stored?
Handle the Crookes Radiometer gently and keep it upright, because the rotor inside the glass bulb is delicately balanced. Store it in its packing away from knocks and direct heat, and avoid shaking the bulb when moving it between classrooms.
Can schools order the Crookes Radiometer in bulk?
Yes. The Crookes Radiometer can be quoted for single classrooms or several schools at once, for institutions, dealers and importers in India and international markets. Send the quantity and destination through the contact page.
Request a Quote
Your quotation for the Crookes Radiometer (SCI-319/013) comes direct from the manufacturer. Use the contact page or add it to the enquiry cart together with other physics apparatus.
Last updated: 24 September 2026
