Yowie Caller

The mythical creature of the Australian Outback

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Purpose -

Can be used to demonstrate the relationship between vibration and sound, harmonics and amplification.

Nature - 

Demo or Experiment

Materials - 

Empty food tin with one end cut out, a shoe lace, a nail punch and hammer

Method - 

· Punch a small hole in the bottom of the tin.

· Tie a knot in one end of the shoe lace and thread the shoelace through the hole in the tin until the know stops it.

· Wet the shoelace

· Hold the tin in one hand and, holding the shoelace between your thumb and forefinger, slide your hand away from the tin. A rather unusual noise should be produced.

Safety -

Be careful of the sharp edges on an opened tin can

Explanation -

As you pull your fingers slide along the shoe lace they cause vibrations that travel up to the tin. The bottom of the tin acts like the membrane on a speaker, and the sides of the tin amplify the sound.

Notes -

An interesting investigation would be to vary the size of the tin or the thickness of the shoelace to see what differences there are.

I have taken this device on school camps as a method rousing late sleepers - very effective!

For those who don't know, the Yowie is a creature of Australian Aboriginal legend who lives in the forest and attacks lone travellers. Perhaps this device is actually a Yowie deterrent, as I have never seen one while using it!

This Wizard was generously supplied by Mr. Tim Birkett