Physics

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Video

Materials

• Toilet paper, or other light paper
• 1 balloon
• 1 pair of scissors
• Mounting putty

Short explanation

The balloon takes electrons from the hair or clothes and thus becomes negatively charged. As the balloon approaches the paper ghost, it makes one end of the ghost positively charged. Since different charges attract each other, the ghost is drawn to the balloon.

Long explanation

When two materials come in contact with each other, there is always a chance that the atoms in one material take electrons from the atoms of the other material. When you rub the balloon against your hair or clothes, electrons will jump from the hair or clothes to the balloon. This makes the balloon negatively charged, because electrons have a negative charge. The hair or clothes that now lacks electrons is thus positively charged. Hair with a positive charge stand up, because all hairs repel each other.

As the balloon comes close to the ghost, electrons in the paper will be repelled by the electrons in the balloon. That is because equal charges repel. The electrons do not leave the paper, but end up further inside the paper ghost, i.e. away from the balloon. The surface of the paper ghost facing the balloon is now positively charged. Because the balloon is negatively charged and one side of the ghost is now positively charged at the surface, they will attract each other.

If the balloon touches the ghost, they will stick to each other, again because of this attraction. Because paper is a bad conductor, few electrons will flow from the balloon to the paper ghost to equalize the charge difference between them.

This is an example of static electricity, i.e. charged particles that, without flowing anywhere, still affect each other with forces.

Over time, the "magical power" of the balloon will diminish. This is because excess electrons leave the balloon in small currents to the air.

Experiment

You can turn this demonstration into an experiment. This will make it a better science project. To do that, try answering one of the following questions. The answer to the question will be your hypothesis. Then test the hypothesis by doing the experiment.

• What happens if you rub the balloon for a longer time?
• What happens if you use something else instead of the balloon?
• What happens if you rub the balloon against something else than hair or clothes?
• What happens if you make the ghost out of something else than paper?

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