Radiometer [Demonstration Guide]
- Google Drive™ folder
Also included in
- The bundle opens with a virtual demonstration of thermoscopes and a discussion of temperature scales. Next we have the classic ball and ring thermal expansion demonstration guide, followed by a demonstration to see the difference between hot and cold in a couple of ways.The Mechanical Universe's "TePrice $36.99Original Price $54.24Save $17.25
Radiometers are fairly inexpensive and fun. Sunlight activates them; incandescent light activates them. In the old days, most household lights used incandescent bulbs. So it always seemed like these things were light-activated.
This demonstration contradicts that notion. A fluorescent light and a black light are tested. Transparent and opaque filters produce surprising results. We develop a new name for the device, more appropriate than "radiometer". (Hence the quotation marks in the title on the cover and student document.)
We end by heating a radiometer set on its side to prevent the vanes from spinning. Then it's allowed to cool. Which way—if either—will the vanes spin?
When I did the activity in remote teaching/distance learning (RT;DL), I conducted the demonstration live over Zoom. I didn't record any video. The included presentation is one I use when conducting the demo. That's why I'm calling this a Demonstration Guide rather than an RT;DL Virtual Demonstration.
I use a 250-W heat bulb on a gooseneck lamp, a 40-W incandescent showcase bulb, a 40-W equivalent compact fluorescent lamp a CFL black light (not a purple-colored incandescent fake black light), a glass filter (blocks IR) and an opaque filter that passes IR. I'm told that black plastic sheeting can do this, too.
Student document (print-friendly Google Docs file on Google Drive)
Instructional presentation (link embedded in answer key)