Spinning Radiometer

Spinning Radiometer
Just as much fun to examine now as when first designed in the 1870's
Stock Number Item Description Availability Price Order Qty
77G09.01 Spinning Radiometer

In stock


First made almost 140 years ago by the British inventor who first developed the vacuum tube later adapted by Edison into a light bulb.

The Radiometer demonstrates energy transfer from natural radiation (light). It consists of a set of four vanes (shiny on one side and black on the other) sensitively balanced on a spindle in a partial vacuum. When exposed to light, the vanes revolve. The blackened vane becomes hotter than its opposite shiny side and repels residual air molecules from its warm surface. This tiny difference in air pressure is what causes the vanes to rotate-the brighter the light, the faster the rotation.

See below for more information.
More Info
Heat energy is being converted into mechanical energy. And it will go on like this forever, so long as the light is on. Delight your children, delight yourself, and impress clients. It's old-fashioned fun and a good lesson in basic physics.

Note: the Radiometer absorbs light; it does not give it off.

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11 reviews 0 5 4.6
Overall Rating
  • Spinning fun

    Mac, 3/3/2014 So much fun!
  • Rotate-not yet!!

    Rob, 2/3/2014 Well, it been in the sunroom-my office-both face west, still looking for it to rotate It is winter in MN, but we still get sun.

    Response By: Garrett Wade Tech Department
    Thank you for your review on the Spinning Radiometer. We are sorry to hear that it is not working properly. We have not had many complaints on these,  so our guess is that you may have received a defective one. Please feel free to return it for another, or if you wish, a refund. Again, our apologies for the inconvenience.
  • Amazing Science

    Lawrence, 1/25/2014 I bought a couple of these for myself and as a gift for young teenagers. It is thought provoking to see the invisible laws of science being played out. Just shining a bright flashlight on the veins will cause them to spin. How does that happen again?
  • Grandpa's Discipline

    Michael Crisp, 12/30/2013 My father in law had one of these in his house in Iowa. When my sons were small, they would go to the farm with their mother for the summers in Iowa. When they became rambunctious, Grandpa would take this off the shelf, set it on the kitchen table, and have my sons sit around and watch this neat science project. He would explain how it worked, and my 3 sons would quiet down, and then be mesmerized long enough to change to more normal normal, in door behavior. what a neat way - no shouting, just a way to slow down their energy and fidgeting, and to make them think/wonder on how this little gizmo worked.
  • Ms. Jennifer Morenus, 12/19/2013 I've got to admit peeking at this before including it in a box for family. I'd never seen one and was curious about it. I took it out and held it up to a sunny window and was fascinated. I think I could have watched for hours. I'm sure it will be a great gift for my science-loving gang!
  • Sun Power

    Andrew L. Petrucci, 2/15/2013 Product works great, my only drawback is that the base of this unit is made of cheap plastic. A nice wooden base would make this a more pleasing and unique display item. It would be a great conversational piece. Maybe it could be offered in two versions.
  • Back to childhood

    GWH, 3/21/2011 Great find! I haven't seen one of these in 50 years. It takes me back to my childhood and the wonder of science.
  • Dr.

    Frank Salimeno, 12/31/2010 Great gift for my grand children. I had one and still have one and it is a fascinating object of science. My three grandsons found it equally interesting. The whole idea is to ask the question: How does it work? That is what science is all about.
  • Interesting Gift

    TMunhall, 12/30/2010 I played with it using different light sources, wondered if I really wanted to give this away to someone else.
  • Way cool !

    Bobby V, 12/19/2010 bought 2 as gifts,, should have bought 1 more for myself!
  • My Grandson will love it

    Paul Bona, 12/18/2010 I got one from you guys a year ago - my grandson thinks it's cool - so, Merry Christmas...
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