High piched noise with glass cup?

Question

I went to the science musem and i c this alot.A guy half filled a cup with water,wet his finger and slid his finger around the rim of the glassit made a high piched noice.I tried it but cant do it.How do u do it?

Answer 1

I think you need a crystal glass to do it.

Answer 2

It doesn't have to be a crystal glass, but it seems to be much easier on a glass with a stem.  The bowl needs to be free to vibrate, and on a stemmed glass, you can hold the base without damping the bowl's vibration.

Hold the base, and just run a wet finger gently and smoothly around the rim.  Try to use a light touch.  Good luck.

Answer 3

You need a thin walled wine glass, with very little water in it.  Very slightly wet the rim and slide your finger around the rim, and you should be able to produce the noise.  A thick walled glass usually won't work.