One of my demonstrations has been published in the December 2010 issue of The Physics Teacher magazine! (And I owe a big thank you to Dan MacIsaac of Buffalo State University for encouraging me to submit the demo for consideration.)
It’s called The Tin Foil Capacitor — and it’s
one of the few articles available as a free download for non-AAPT members not free anymore.
In the demo, an electroscope is connected to a rolled up sheet of aluminum foil with an alligator clip wire. The purpose of the demo is to illustrate: (1) excess charges on a conductor reside on the surface of the conductor; and (2) the charges spread out over as large a surface area as possible. The electroscope is charged up and then the aluminum foil is unrolled and then rolled back up again. Here’s a video of the demonstration in action:
I also have a simple interactive lecture demonstration (ILD) worksheet to use with students before and after doing the demo: Tinfoil Capacitor ILD Sheet.
Update: A new and improved ILD sheet from physics teacher Michael Sivell — TinFoilCapILD_Sivell
More Interactive Lecture Demonstrations from the University of Maryland PER Group.
Frank this is awesome. Our electroscopes are too crappy and finicky for me to have much of a use for them, so this might be enough for me to convince my colleagues to spring for some of the fancy PASCO ones.
Awesome. Don’t you have something in the cue for my journal as well? If not, you should!
Weren’t you doing a special SBG edition of your journal? Let me know the details!