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The vanes, or wings, in this solar radiometer are alternately dark and light in color. When the light strikes these wings it transfers heat to each one - but not at the same degree. The lighter wing reflects the rays and the darker wing absorbs. The stronger the light, the more energy there is to heat up the darker side of the wing causing the wings to spin faster. Great for science projects, as a gift or as a desk amusement!
These will spin under the direct solar light or a nearby incandescent light bulb. Please note that these will not spin in standard office or home ambient light.
Features:
- Uses heat transfer to spin
- No batteries required; the radiometer is powered entirely by light
- Either solar or indoor light works
- Great desk toy
- Great for solar science lessons
Age14+
Approx. Ship Size5.25 x 3.25 x 3.25 in
13.34 x 8.26 x 8.26 cm
13.34 x 8.26 x 8.26 cm
Weight0 lb 3 oz
0.08 kg
0.08 kg
Customer Reviews
pete from usa, Pennsylvania
very nice solar radiometer! my grandson is amazed to watch it react to the sun
Crookes Solar RadiometerCP from USA PA,Hollidaysburg
Radiometer works fine, but the inside of the glass has a film on it. It is very annoying when in bright sunlight.
Great giftAlicia Flaherty from U.S.A, Colorado, Fountain
Works just like it's supposed to. Looks nice, and I know my brother will love this. Bought this for him to replace the one he had as a child that was stolen. So happy that these are still popular enough to be sold.
directly observable interesting physicsMark ODell from USA, CA, Los Angeles
Motion directly from light never gets old. This motion, however, is not due to photon momentum radiation pressure, or the direct pressure from gas warmed by the black faces. Such simple explanations turn out to be wrong. This is a light-driven heat engine. Even James Clerk Maxwell initially disagreed with Osborne Reynolds about the mechanism, so we are in good company watching and wondering. See Wikipedia Radiometer references for a lucid discussion, but know there is much more going on than the common explanations most of us learned when first seeing a Crookes Radiometer ("light-mill"). Cooling causes direction reversal. Improving the vacuum stops motion altogether. Radiation pressure is real, but the effect is too small here. The important mechanism has more in common with the flow of heat or superfluid helium than the momentum of photons or the pressure of bulk hot gas. The black sides do get hotter, but the ultimate magic of motion apparently happens at the edges of the vanes, not the faces.
Good Classroom ToolCynthia from USA, UT, Draper
This is an awesome way for students to learn that solar radiation is a form of energy.
Radiometer funMaria from Cedar Rapids, IA
Love to watch this work and think about the science behind it. Great tool for teaching about energy.
Great Conversation Piece!Eric Holmes from Moose Jaw, Canada
Everyone that sees it will stop and look at it rotating and then will have a theory on what makes it rotate.
SolarRadiometerJoan from Tulsa, Oklahoma
This is so fun. I broke my mother's radiometer, so had to replace it. A good price for a great product.
Undisclosed Verified Buyer
intriguing, fun
