Edited by (Scott Holloway)
A Tesla coil is a type of resonant transformer circuit invented by Nikola Tesla around 1891. It is used to produce high voltage, low current, high frequency alternating current electricity. A Tesla coil consists of two, or sometimes three, coupled resonant electric circuits, but is difficult to define precisely as Tesla experimented with a number of different configurations. Tesla used these coils to conduct innovative experiments in electrical lighting, phosphorescence, x-ray generation, high frequency alternating current phenomena, electrotherapy, and the transmission of electrical energy without wires for point-to-point telecommunications, broadcasting, and the transmission of electrical power.
Some nice video demonstrations presented by Santa Cruz Institute for Particle Physics outreach program.
One must take care not to be struck by an arc, as a burn on the skin may occur.
My son, Caden, experiencing broadcast electricity.
Notice the bulbs in both pictures are fluorescent bulbs, not incandescent. What can be really impressive is to take a "burnt out bulb" from an existing light fixture, place it near the tesla coil and it will glow again. It is usually the ballast or electrical ends that fail, as long as the tube is still intact the enclosed gas will glow in an electric field.
My daughter, Jenna, (the light of my life) was mesmerized by the hand held light bulb.