Concepts

Transformers, LC circuits, resonance

Overview

The Tesla coil is a resonant transformer that generates AC electric fields that can power fluorescent lights and neon tubes, as well as produce high-voltage arcs.

It is essentially structured as a pair of LC circuits coupled to each other through the inductors, with a transformer exciting one of the LC circuits. As a resonant transformer, the ratio of inductor turns in the Tesla coil does not translate to a constant voltage ratio.

This is a dramatic and attention-grabbing demonstration, but it is also a bit dangerous. Read the important notes carefully.

Details

Equipment

• [1] Tesla coil with grounding wand
  
• [1] Fluorescent tube
• [1] Neon lamp
  
• Extension cord (if necessary) 

Safety Equipment

• [1] Safety glasses
  
• [2] Safety glove
• [1] Pair of earmuffs

Classroom Assembly

1. Place the Tesla coil somewhere far from electronics.
2. Plug in the Tesla coil into an outlet you can reach without getting too close to the Tesla coil.
   

Important Notes

• Do not let anyone with medical devices (e.g. pacemaker, hearing aids) near the Tesla coil.
• Users should put personal electronics (e.g. phone, laptop) somewhere far from the Tesla coil.
• This demo makes ozone, which is a poisonous gas. Use only when a room with good ventilation, and do not operate for very long.
• Do not look directly at the spark gap inside the plexiglass box. It makes UV light.
• Do not let the Tesla coil arc directly to the fluorescent tube or neon lamp while you are holding it, even with gloves on. It will give you a shock.
• Try not to get shocked. Even if it doesn't hurt much, it can still give you electrical burns over time.
  
• The Tesla coil is quite loud. Hearing protection is recommended.

Script

1. Turn off the room lights.
   
2. Put on the earmuffs, a safety glove, and the safety glasses.
   
3. With one hand, hold the grounding wand close to the Tesla coil's top electrode and turn on the Tesla coil with the other hand,  the gloved hand.
4. Make arcs of various lengths using the grounding wand.
   
5. Put down the grounding wand far from the coil and use the gloved hand to bring the fluorescent tube near the coil without arcing to it. The tube should light up.
   
6. Use the gloved hand to bring the neon lamp near the coil without arcing to it. The lamp should light up.
   
7. Bring the grounding wand close to the Tesla coil and turn off the coil.
8. Turn on the room lights.
   

Additional Resources