Tesla coil. Artificial lightning is produced by a large Tesla coil built by the Tesla Coil Builders Association in the USA. Nicknamed Nemesis, this coil is essentially a large air-core transformer with a capacitor. Tesla coils are named after their inventor, physicist Nikola Tesla (1856- 1943). The coil is designed to give a high- voltage, high-frequency spark. Nemesis creates a spark 60 times per second using mains electricity, but at over 1 million volts. Photographed in Richmond, Virginia, USA.