Introductory demonstration materials

[neomagus00]

Hello all,
While searching for a holiday gift for a younger sibling (who is rapidly becoming interested in the sciences), I remembered a demonstration from a high school physics course that sparked my own interest in physics. It involved a unique object - a light bulb with a needle and 4 black and white squares balanced upon it, in place of the filament. Shine a flashlight on the pinwheel and it spins - a visually appealing demonstration of how photons have energy, and a great launching point for more questions and learning (grab their attention with the mysterious spinning squares, and parlay that into questions about the nature of light, mass, etc.).

I can not for the life of me find this unusual object, or anything like it. Any recommendations? I remember this demonstration in particular, but any similar demo would be great, and any ideas would be very much appreciated.

Thanks!

 

[афк]

Hello, the object you've described is usually termed 'light-mill'.

http://math.ucr.edu/home/baez/physics/General/LightMill/light-mill.html"

 

[Redbelly98]

Besides light mill, these are also known as radiometers or Crookes radiometers.

An online search of "radiometer" shows many for sale, at around 9 $US.

You might also find them in the gift shops at planetariums or science museums.

 

[neomagus00]

Thanks to both of you, that was exactly what I was looking for. Good call pointing me to the explanations, too - I'm a physics grad from Carnegie Mellon and I still thought it was just radiation pressure! (In my defense, I didn't know it spun the wrong way).

Again, much appreciated.