Decorative Radiometer - 18cm

A 18cm high lovely decorative radiometer that spins it little heart-out in sunlight.
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$39.95 Incl. GST
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A lovely decorative radiometer that spins it little heart-out in sunlight.

Consisting of a glass bulb with a partial vacuum containing a low friction spindle. When electromagnetic radiation such as light or even heat from a person's hand enters the bulb the vanes turn, the black away from, and the white towards, the source of radiation.

This hand made radiometer makes an attractive room ornament and is an interesting lesson is energy transformation.

Ages: 12+ under adult supervision, made of fragile glass

What you get

Decorative Radiometer, hand made from glass, measuring 18cm high. This is not a toy, the glass is fragile.

How does it work?

Also known as the light mill, or solar engine, the radiometer demonstrates how heat can be transformed into movement energy. Its invention in 1873 is credited to Sir William Crookes, an English physicist.

When the black vanes inside the radiometer are exposed to a warm energy source like the sun or a table lamp, they spin. The more powerful the heat source, the faster the vanes spin.

The black side of the vane absorbs heat faster than the polished silver/white side, raising the temperature and pressure of the air molecules behind the black vanes and causing the spinning motion.


  • Heat Engine (the radiometer effectively becomes a heat engine when heat energy, such as light, is directed at it))
  • Sustainable and solar energy.
  • Thermodynamics.
  • Black-body absorption the black vanes inside the radiometer heat up quickly because they absorb all radiation falling on them. This contrasts to the other white/silver side of the vanes.
  • Light energy and electromagnetic radiation.

WARNING: CHOKING HAZARD - Small Parts. Not for children under 3 years.

More Information
Length (cm) 14
Width (cm) 25
Height (cm) 14
Age Group 11-12 Years, 12+ Years
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