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Science project idea

The spoon that rings like a bell: sound through string

Vibrations pass much better through a solid string than through air. A steel spoon hung from a string and tapped on a table sounds faint, but when you press the string to your ear it rings like a deep bell.

Make it yourself7 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

Vibrations pass much better through a solid string than through air. A steel spoon hung from a string and tapped on a table sounds faint, but when you press the string to your ear it rings like a deep bell.

The science

When the spoon is tapped it vibrates, and the vibrations travel up the string, which is a solid. Sound passes through solids better than through air because particles are packed close and pass the vibration on quickly. The string carries the vibrations to your ear bones, which makes the note rich and loud.

Materials

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

  • A steel spoon or large fork
  • A 1 metre piece of cotton string or wool
  • A table
  • A second spoon
  • Another piece of string for comparison
  • A friend
  • A notebook

Safety

For this project: Do not hit the table hard or swing the spoon wildly, as it could hit the face. Keep the spoon away from your ear at all times, and only the string touches your ear.

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

7 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. Tie the middle of the string around the spoon handle so the spoon hangs with both ends of the string free.

  2. Hold the ends of the string against your ears with your fingers, so the spoon dangles in front of you.

  3. Ask a friend to tap the spoon gently with a second spoon.

  4. Listen to the deep ringing sound that comes through the string.

  5. Now hold the spoon by its handle and tap it, so you hear only the sound travelling through air.

  6. Compare the two sounds and draw a picture of each path.

  7. Try longer string, wool, wire and thin thread and note which carries the sound best.

What you should see

Through the string, the spoon sounds like a big bell, and through air it sounds like a quiet clink. This shows that solids carry sound well.

Viva questions

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

1What is sound?

Vibrations that travel through a material.

2Why does the string sound louder?

Solids carry vibrations better than air.

3Can sound travel in a vacuum?

No, it needs a material to travel through.

4How do we hear underwater?

Water also carries sound well.

Free ebook: Viva Questions for Science Projects

Take it further

Make a tin can telephone and compare string types and string lengths.

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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