Screaming Cups

You've never heard a sound effect quite like this coming out of an ordinary cup!

You will need:

Fishing line or smooth string (it's worth trying a few different types to find what works best)
A plastic cup (yoghurt pots work too)
A damp cloth
Tape or modelling clay

What to do:

Cut a length of string about the height of the cup.
Stick the string to the centre of the inside of the cup with the tape or the clay.
Turn the cup upside-down. The string should hang down inside the cup.
Draw the damp cloth along the length of the string; this starts the string vibrating as the cloth slips and sticks - which is just how a violin bow works.
What in the name of tarnation is that hideous row? Is someone killing a chicken?

What’s going on?

Vibrating a piece of string in the same way with a damp cloth produces a sound, but it's very quiet. Adding the cup to the end of the string creates a larger surface to vibrate, amplifying the sound.


Want more?

You can do exactly the same as above, but on a bigger scale, with a bucket. Or better, use a variety of differently sized buckets, with bowls and cups and even bins. If you can get a really giant bin (half a metre in diameter) you get a really deep noise that sounds more like a cow than a chicken!

Look for this and many more cool experiments you can try at home in the Little Book of Experiments (click to open)