What You Need:
- Two balloons
- Fabric made of wool of synthetic materials that can create a static charge (a wool sock works perfectly here)
- A dry day (with little humidity)
What You Do:
- Inflate both balloons.
- Charge one of the balloons by rubbing the cloth against it.
- Have your child place the charged side of the balloon against a wall. Discuss what happens next!
- Have your child try pressing the balloon against different surfaces to see if it sticks. The balloon may need a second charge before he's done!
- Try pressing the carged balloon against the second balloon. Did they stick together?
- Have your child charge both balloons. Make a hypothesis: Will the balloons stick together when both are charged? Try it together to find out.
What's Going On? Rubbing the balloon with a piece of fabric gives it a negative charge, also known as static electricity. Enough static electricity will force the balloon to stick to neutrally charged surfaces, such as walls, by attracting the positive charge to the surface. The balloon is light, so this charge is enough to cause it to stick to the wall.
If you try to leave the balloon on the wall, eventually it will fall to the ground. In this case, the static charge dissipates over time, causing the balloon to lose its negative charge and unstick itself.
The two balloons will stick together if one is charged in the same way the balloon sticks to the wall. However, two negatively charged balloons will repel each other.