Open the “John Travoltage” applet here: https://phet.colorado.edu/en/simulation/
ID: 1884692 • Letter: O
Question
Open the “John Travoltage” applet here: https://phet.colorado.edu/en/simulation/john-travoltage Click on the rightmost leg in the figure and move it back and forth a few times.
1. What happens as you drag John’s foot across the carpet? Why does it happen? What must be true about the carpet?
2. Why do most of the negative charges stay near John’s foot? Why do some of them spread throughout his body?
3. Next, drag the rightmost hand in the figure down towards the doorknob. What happens? Why does it happen?
Explanation / Answer
1. While rubbing his foot on the caarpet some electons appear onto his foot and travels up slowly.
The force of friction between the carpet and the shoe makes some electrons from the carpet to detach and they get collected on the shoe.
The carpet(wool fiber) is a great source of electron when rubbed against a rubber sole of the shoe.
2. Human body is not a great conductor of electricity and the charges are insulated from the ground so they cant flow back to the ground.
As negetive charge builds up on a single object, the gathered electrons repel each other and slowly move apart. They move slowly because human body is not a very good conductor of electricity.
3. All the charges flows out through an ark to to the metal doorknob.
As a finger comes near a doorknob the electrons have finally a path to go to the earth. Air work as an insulator and with a few electrons the energy of the charges are too little to ionize air. As more charges start to build up the air becomes ionizable. Finally the electrons move through the ionied air through a spark (known as electrostatic breakdown of air). Finger is a pointy object, this type of discharge through a pointy object is known as coronal discharge. In the end all charges move out and Travolta becomes nutral again.
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