Photos of Electric discharge showing the lightning-like plasma filaments from a Tesla coil.
A Tesla coil is a type of resonant transformer circuit invented by Serbian-American scientist Nikola Tesla around 1891. It is generally used to generate very high voltage, low current, high frequency alternating current electricity.
It's very impressive to see the high-voltage lightnings arcs produced by large Tesla coils. Don't try this at home!
For more information about Tesla Coils, check the wikipedia article: en.wikipedia.org/wiki/Tesla_coil .