How did Nikola Tesla make circuits work?

Answer 1

Tesla arrived in the United States in 1884, at the age of 28, and by 1887 had filed for a series of patents that described everything necessary to generate electricity using alternating current, or AC. To understand the significance of these inventions, you have to understand what the field of electrical generation was like at the end of the 19th century. It was a war of currents -- with Tesla acting as one general and Edison acting as the opposing general.

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 transformer operates in a significantly different fashion than a conventional transformer. In a conventional transformer, the windings are very tightly coupled, and voltage gain is limited to the ratio of the numbers of turns in the windings.

However, unlike a conventional transformer, which may couple 97%+ of the magnetic fields between windings, a Tesla coil's windings are "loosely" coupled, with the primary and secondary typically sharing only 10-20% of their respective magnetic fields and instead the coil transfers energy (via loose coupling) from one oscillating resonant circuit (the primary) to the other (the secondary) over a number of RF cycles.