MIT Physics Demo -- The Wimshurst Machine

A Wimshurst electrostatic generator - http://en.wikipedia.org/wiki/Wimshurs... - , working on the principle of induction, generates high voltage differences and sparks between two movable electrodes. By increasing the distance between the electrodes, higher potential differences can be built up.

Electrostatic induction - http://en.wikipedia.org/wiki/Electros... - refers to the principle that charges in an object (especially a conductor) redistribute themselves in the presence of nearby charges. Opposite charges are attracted to each other, while similar charges are repelled.
Larger charges can be stored by connecting the knobs to Leyden jars which are component parts of the machine.

See the original video and more on MIT TechTV here - http://techtv.mit.edu/videos/5303-the...