text: Q:
  
  How does a Tesla coil work?
  
  I've been hearing a lot about Tesla coils recently and about resonance and similar things. I was wondering if someone can describe its method of working and how it can tap into ambient energy to output more power than its input power?
  
  A:
  
  It does no such thing. A Tesla coil is just a resonant transformer with a really large turns ratio. It does not create more power out of thin air.
  It works like any transformer, just that here the frequency is chosen such that the transformer has the best efficiency.
  
  