Static electricity is a great school project because it lets you see invisible electric charges at work. When you rub a balloon on dry hair or a wool cloth, the balloon can make hair stand up, stick to a wall, or bend a thin stream of water. These effects happen because tiny particles called electrons move from one material to another.
The project is simple, safe, and uses common materials like a balloon, hair, paper bits, and a faucet.
Key Facts
- Static electricity is the buildup of electric charge on an object.
- Rubbing a balloon on hair can transfer electrons, giving the balloon a negative charge.
- Opposite charges attract, and like charges repel.
- A charged balloon can attract neutral objects by shifting their charges slightly.
- Electric force gets weaker as distance increases.
- Charge is measured in coulombs, written as q in equations such as F = kq1q2/r^2.
Vocabulary
- Static electricity
- Static electricity is electric charge that builds up on the surface of an object and stays there for a short time.
- Electron
- An electron is a tiny negatively charged particle that can move from one material to another.
- Charge
- Charge is a property of matter that causes electric attraction or repulsion.
- Attraction
- Attraction is a pulling force between objects, such as between opposite charges or a charged object and a neutral object.
- Polarization
- Polarization is the shifting of charges inside a neutral object so one side becomes slightly more positive or negative.
Common Mistakes to Avoid
- Using a wet balloon or wet hair: moisture lets charge leak away, so the balloon will not hold much static electricity.
- Rubbing the balloon only once or twice: too little rubbing may not transfer enough electrons to create a visible effect.
- Holding the balloon too far from the hair, paper, or water: electric forces weaken with distance, so the balloon must be close without always touching.
- Thinking the balloon creates new charge: rubbing does not create charge from nothing, it moves electrons from one material to another.
Practice Questions
- 1 A student rubs a balloon on dry hair for 20 seconds, then holds it 2 cm from small paper bits. If the balloon is moved to 6 cm away, how many times farther away is it, and would you expect the attraction to be stronger or weaker?
- 2 A class tests how long a balloon sticks to a wall after rubbing it for different times. It sticks for 15 seconds after 5 seconds of rubbing and 45 seconds after 15 seconds of rubbing. What is the ratio of rubbing times, and what is the ratio of sticking times?
- 3 Explain why a charged balloon can bend a thin stream of water even though the water has no overall charge.