Sunday, March 3, 2013


We did some of the classic experiments in electrostatics, electric current generation, and associated phenomena in Physics II Laboratory Friday. 

First, students made crystal radios using small kits. The kits weren't very good, and students struggled with the instructions and some of the fiddly processes. But once we had one or two working, we set them aside and switched to other experiments, then combined the two.

We then ran the Van der Graaff generator through its paces, using it to visualize first electrostatic discharge (sparks, seen above), then to light a CFL light bulb, then, with the aid of some aluminum pie plates and soap bubbles, charge transfer. 

(The VdG can light a florescent bulb, the pie plates, placed on top of the sphere, fly off the VdG, one by one, as they accumulate charge, and the soap bubbles are initially attracted to the VdG then repelled violently.)

Here are students fiddling with their radios' electronics:

And here, of course, is the classic VDG genny charge transfer experiment: find the student with the longest driest hair, stand him on an insulator (an old milk crate), and charge him up until he crackles and his hair sticks straight up. 

Samuel was, I must say, perfect for purpose. 

(Thanks, Sam, for contributing your excellent hair and sense of humor to science.)

Then, we pulled out a hand-held Tesla coil and used it to visualize electric current transfer using sparks and an old light bulb. 

Finally, we transmitted Morse signals to the crystal radios using bursts of Tesla coil energy (because spark transfer makes Hertzian waves), essentially replicating the early spark transfer radios.

Here are some You Tube videos showing similar experiments:

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