The John Travoltage simulation from PhET lets you move John’s foot across the carpet and then bring his hand near the doorknob to see when he gets a shock. You can watch extra charges build up on his body and jump across as a spark, which makes static electricity easy to picture. It is free, runs in any browser on a phone, tablet or laptop, and it is a great fit for static electricity and electric charge lessons in Tamil Nadu State Board (Samacheer Kalvi) Science and Physics.
What is the John Travoltage simulation?
This interactive simulation shows a character named John standing on a carpet next to a metal doorknob. You drag his foot across the carpet and watch electric charges gather on his body. When you move his hand close to the doorknob, the charge can jump across the gap as a spark and John gets a shock. Because it runs on HTML5, there is nothing to install, and it works on phones, tablets, Chromebooks and computers.
Elementary school to university
Drag John’s foot and arm
Phone, tablet, Chromebook, PC
English
PhET’s learning goal is to describe and draw models of common static electricity ideas: transfer of charge, attraction, repulsion and grounding.
Launch the John Travoltage simulation online
Tap or click inside the player and drag John’s foot and arm. Use the full-screen button in the player for a bigger view.
Credit: University of Colorado Boulder
How to use the John Travoltage simulation, step by step
- Predict first. Before you move anything, say what you think will happen to John’s charge.
- Rub the foot on the carpet. Drag John’s foot back and forth and watch the extra charges collect on his body.
- Move the arm toward the doorknob. Bring his hand slowly closer and look for the moment a spark appears.
- Compare the amount of charge. Try rubbing for a short time and for a long time. Does a bigger build-up change when the spark jumps?
- Watch the charge after the spark. Notice that the extra charge flows away and John becomes neutral again.
Tip for students: count the extra charges on John before the spark and after it. The difference shows how much charge flowed to the doorknob.
The idea behind the simulation: Q = n × e
Q = n × e
Here Q is the total charge in coulombs (C), n is the number of extra electrons and e is the charge of one electron, about 1.602 × 10−19 C. When John’s foot rubs the carpet, electrons move onto him, so he gains a net negative charge. The more electrons he collects, the larger the charge.
Worked example: If 1 × 1010 extra electrons gather on John, the charge is Q = 1 × 1010 × 1.602 × 10−19 ≈ 1.6 × 10−9 C, which is about 1.6 nC. Even a very small charge like this can cause a visible spark on a dry day.
Static electricity key terms explained
These are the words you will meet while using the John Travoltage simulation, with simple meanings.
Static electricity
A build-up of electric charge on an object, usually after rubbing two materials together.
Electric charge
A property of matter. Charge is positive or negative and is measured in coulombs (C).
Charge transfer
Electrons move from one object to another when they rub. The object that gains electrons becomes negative.
Electron
A tiny negative particle. Electrons, not protons, are the particles that move in static electricity.
Attraction and repulsion
Opposite charges attract each other. Like charges push apart.
Grounding
Connecting an object to the Earth, or to a conductor like a metal doorknob, lets extra charge flow away.
Electric spark
A sudden jump of charge through the air between two objects when the build-up is large enough.
Conductor and insulator
Conductors, like metals, let charge move easily. Insulators, like a carpet or plastic, hold charge in place.
Common mistakes: Saying that protons move when John rubs the carpet (only electrons move), thinking the spark creates new charge (it only moves charge that was already there), and forgetting that John becomes neutral again after the spark.
Try the charge calculator (practice what you explore)
Enter the number of extra electrons, in billions, to see the total charge. Then tap a “what if” button.
What you will observe in the simulation
| Situation | What happens |
|---|---|
| Foot rubs the carpet | Electrons move onto John, so he becomes negative |
| Rubbing for longer | More electrons collect on his body |
| Hand moves close to the doorknob | Charge jumps across as a spark |
| After the spark | The extra charge has flowed away and John is neutral |
| Extra charge on John | Like charges repel each other, so they spread out over his body |
Classroom activities for teachers
The John Travoltage simulation fits a single 40-minute period.
- Predict and test (10 min): students write a prediction before each action, then check it in the simulation.
- Draw the model (10 min): students sketch the charges on John, the carpet and the doorknob before and after the spark.
- Spark distance (10 min): compare how close the hand must be for a spark after a little rubbing and after a lot.
- Exit ticket (10 min): students explain in two sentences why John gets a shock only when his hand is near the doorknob.
Looking for the matching chapters? Browse the Science and Physics books on TN SchoolBooks and download the Samacheer Kalvi PDFs, then use this simulation to make the electricity lessons visual. More free science simulations and textbook PDFs are on the home page.
Quick quiz: test your understanding of static electricity
Score: 0 / 5
John Travoltage simulation: frequently asked questions
Is the John Travoltage simulation free?
Yes. PhET simulations are free to run online in a browser. Check PhET’s licensing page for reuse terms.
Does it work on a mobile phone?
Yes. It is built with HTML5 and works on phones, tablets and Chromebooks. Use landscape mode or the player’s full-screen button for a bigger view.
Why does John get a shock from the doorknob?
Rubbing his foot on the carpet moves electrons onto his body. When his hand gets close to the metal doorknob, the extra electrons jump across the gap as a spark, which he feels as a shock.
Which particles move in static electricity?
Only electrons move. Protons are held inside atomic nuclei. An object that gains electrons becomes negative, and one that loses them becomes positive.
The John Travoltage simulation turns invisible charges into something you can drag, test and see. Explore it, take the quiz above, and keep experimenting until predicting when the spark appears feels easy.