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Science project idea

Rubbed balloon lifts paper bits and bends a thin stream of water

Rubbing a balloon on hair gives it an electric charge. A charged object attracts light things like paper bits and even bends a stream of water.

Make it yourself8 numbered steps, the materials and the science, all free.Go to the stepsGet a ready-made kitReady-made models, kits and spare parts in the store under Physics.Browse PhysicsAsk on WhatsAppAsk the head office whether a model or kit for this idea is available.Send a message

What it shows

Rubbing a balloon on hair gives it an electric charge. A charged object attracts light things like paper bits and even bends a stream of water.

The science

When two different materials are rubbed together, electrons move from one to the other. The balloon gains extra electrons and becomes negatively charged. It then attracts paper bits and water because the charge in them shifts slightly, so the near side has opposite charge and is pulled towards the balloon. The effect is weaker in humid monsoon weather, because moist air carries charge away.

Materials

Cost: under Rs 50. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.

  • 2 balloons
  • A wool cloth or dry hair
  • Tiny pieces of tissue paper
  • A plastic comb
  • A tap or a bottle with a small hole giving a thin stream
  • A notebook
  • A dry sunny day

Safety

For this project: An adult must supervise the use of balloons with children under 8 and make sure no burst pieces are put in the mouth.

Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.

All the safety rules

Step by step

8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.

  1. Blow up a balloon and tie it. Blow up a second balloon to a different size.

  2. Rub the first balloon firmly on dry hair or wool for 15 seconds.

  3. Hold it above the paper bits without touching and see the bits jump to it.

  4. Open the tap to a thin steady stream, about as thick as a pencil lead. Bring the charged balloon near the stream without touching it, and watch it bend.

  5. Rub the balloon on your hair and place it on a wall. Watch how long it sticks.

  6. Compare the comb and the balloon, rubbing each for the same time, and count how many paper bits each lifts.

  7. Try again on a dry day and on a humid or rainy day and note the difference.

  8. Write a table of materials rubbed and what happens in each case.

What you should see

The rubbed balloon picks up paper bits and bends the water stream, while the unrubbed balloon does neither. The effect is weaker on a damp day.

Viva questions

A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.

1How does the balloon become charged?

Electrons move from the hair to the balloon when they are rubbed.

2Why does it attract paper that is not charged?

The paper’s charges shift a little, so the near side is attracted more than the far side is repelled.

3Why does the effect fade on damp days?

Moisture in the air carries the charge away.

4What are two examples of static electricity in nature?

Lightning and the crackle when a sweater is taken off.

Free ebook: Viva Questions for Science Projects

Take it further

Hang two charged balloons side by side on threads and see them push each other apart.

Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.

Free ebooks for this project

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