Gzzzzzt!

One of the cool things about teaching physics is the demos we get to do. On the last day of class (Friday) I did the Tesla coil. This thing wraps up many of the concepts we’ve been playing with over the last 2 months: Inductors, Transformers, Capacitors, Resistors, and putting it all together in a rather specticular fasion. I’ve a few more pictures on my flickr account. One component — the capacitor and spark-gap chamber — we found in a catalog dated back to 1919 — the bits of this demo are old!!

There is a great web page that describes how a tesla coil works with a cool animated gif. Wikipedia also has a history (though not very well written).