title: Tesla coil
text: A Tesla coil is an electrical machine invented by Nikola Tesla in 1891. It is a radio-frequency oscillator and resonant transformer that generates high voltage electricity at low currents. One use is to make lightning bolts. Most are used nowadays to entertain. "Singing Tesla coils" have also been made that can create music. 
   It works on the principle of electromagnetic induction
  
  Transformers (electrical)