There are some truly epic pictures of Tesla coil experiments online – mind-blowing images of purple electricity enveloping cars and striking humans in cages. But how do they work, and what exactly is their function?

Aron Koscho, a pioneer in Tesla coil production and application, recently built a twin Tesla coil system for Björk’s Biophilia live show. “A Tesla coil is a special type of transformer that uses a resonant circuit to produce very high voltages. Think of it like shaking a flagpole in the school yard; you push and pull with the same amount of force but the longer you do it the more the pole moves from side to side.”

Having built his first coil when he was 12, Koscho has since started a business in building high voltage equipment and pursued the industrial application of Tesla coils through his company, Applied Tesla Technology Inc. Proud to have made what he believes is the most reliable, and highest quality Tesla coil system available today, his ultimate dream is to build the largest Tesla coil in the world.

The mystery and appeal of Tesla coils lies in the striking visual beauty of the ever-changing neon electric currents and radical arc shapes that form during experiments. One of the most common questions Koscho gets asked is whether the colour of the electrical currents can be manipulated. “It is possible to create some colour change near the base of the arc by the use of certain chemical compounds at the breakout point,” he says. “Other than that, it is governed by the gases in the atmosphere around the coil. Since air is primarily nitrogen, we get a purple colour to the arc. If the atmosphere were changed to say, neon, we would get a pink arc.”

The coil he built for Björk was a twin Tesla coil system that plays musical notes through its 1.5m long electrical arcs. “The system is housed in a large aluminum cage and will be hung above the band. It’s a very cool effect!”

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Björk: “Early in the project I came across Tesla coils. They seemed to be the core of Biophilia, especially the educational angle: if the natural elements impress a child with their power, then what better than lightning? I guess the natural elements are the superheroes of Biophilia and a Tesla coil allows you to invite one of them into your house...”

Text By Veronica So