Detecting vibrations

Setting up the vibration detector.

Setting up the vibration detector.

Seismometers detect the vibrations produced by earthquakes.

If the ground moves underneath a mass that is not fixed down, the mass will tend to stay where it is and let the ground move underneath it: seismometers just measure this relative motion, and it is more convenient if we can record and display this motion on a computer screen.

This activity shows you one way to detect vibrations and display them on a computer screen.

Warning!

The strong forces produced by supermagnets can cause injury or damage to other equipment or to the magnets themselves. You must follow any additional safety information provided by your teacher before you begin this activity.

Task instructions

  1. Connect the coil of the vibration detector to the input socket on the adaptor. Plug the adaptor output lead into the microphone input of a computer.
  2. Open the sound-editing software: when you are ready to start, you should be able to see a single input channel on the screen.
  3. Tap the bench sharply: sketch what you can see on the screen.
  4. How is the pattern you see similar to a seismogram?
  5. Tap again, but further away. Make another sketch next to the first one, to show the difference.
  6. Tap the bench sharply, then tap it more softly. What difference does this make?
  7. How is your vibration detector different from a real seismometer?
  8. How are the vibrations you detected the same as those from an earthquake? How are they different?

Teachers' notes

Detecting vibrationsDetecting vibrations

Students use a magnet and coil and sound-editing software to detect vibrations.