This activity demonstrates the concept, described by Nikola Tesla, that electricity can be conducted through air. While many of us think of wires as the main mechanism for conducting electricity (for example, throughout our house or while charging a phone), air also conducts electricity. This demonstration shows us a hands-on example of air conducting electricity.
To see this effect, we use a large (in this case, 1 million Volt) Tesla coil, and ask an audience member to hold a fluorescent light about 15 feet away from the coil. When the coil is turned on, it produces electricity, which runs through the metal rod on top of the coil before traveling through the air to the fluorescent light held at a distance. The electricity enters the light and creates a current, which causes the fluorescent light to turn on as if it were plugged into the wall!
Activity/Demo Instructor Notes
- As an instructor, first familiarize yourself with the Tesla coil. The Tesla coil is operated by a control panel, which has several labeled switches. Read the instructions on the panel that describe how to use the Tesla coil safely.
- Before turning on the Tesla coil, make sure the metal rod protruding from the top of the Tesla coil is not close to another object (such as you!), otherwise the current might arc to the closest object and shock it. This would be like getting struck by a small lightning bolt, so make sure you (and whoever is holding the fluorescent light) is at least 15 feet away from the Tesla coil.
- Once you are a safe distance away from the Tesla coil, practice turning it on and off following the numbered steps on the control panel. Note that the Tesla coil is very loud when turned on.
Performing the demo:
- First, ask some guiding questions while introducing the demonstration. If you have a smaller audience, feel free to ask them more questions, since a smaller audience will usually participate more than a larger crowd.
- What is electricity?
- Where do you see/use electricity in your everyday life?
- How does electricity get to your home? How do we conduct electricity?
- How does wireless charging work?
- What is lightning? How is this like wireless charging?
- Do you think we can use this 1 MILLION Volt Tesla coil to light up this fluorescent bulb without it being connected to any wires?
- Next, pick a volunteer from the audience to hold the fluorescent light. Ideally, the audience member should be seated about 15 feet from the Tesla coil, but not closer. Pick someone who is sitting near the coil, so they aren’t tempted to walk any closer to the arcing bolts of electricity when the coil is turned on.
- Now we’ll show that electricity can be conducted through air without wires.
- Warn the audience that the Tesla coil is loud.
- Turn off the lights (so that it’s easier to see the fluorescent light glow).
- Follow the numbered instructions to work the Tesla coil and leave it on for about 5-10 seconds so the audience can see the current flow through the fluorescent light. It will be loud and bright, and the audience should love it!
- Turn off the Tesla coil and thank the audience member for participating.