# Natural frequency of a wine glass

1. May 14, 2005

### sniffer

Does any body know the typical natural frequency of an empty wine glass?
I want to conduct a demo experiment of breaking a wine glass with
a sound wave from a distance. Has anyone here done it before?

I need a signal generator (sine wave) and an amplifier. What kind of
loudspeaker do I have to use? What frequency?

Thanks.

2. May 14, 2005

### brewnog

Ping the wine glass with your finger. The note you hear will be the resonant frequency. Either measure it with a microphone and a-silly-scope, or just compare it with a known note on a piano or guitar or something.

3. May 14, 2005

### zoobyshoe

No such thing as a "typical" wine glass frequency. Each glass will be different.
I've played around with making wine glasses sound by running a wet finger around the rim. This is what you need to do to find the natural frequency of the glass in question.
The only way to find the frequency you need is to start off as close to the pitch of the glass as you can and then fine tune your generated signal. Wine glasses are high pitched, so I'd say use the best tweeter you have available. In general design your system for maximum amplitude.

4. May 14, 2005

Also, you can't do this with cheap wine glasses as these have a wider frequency range at which they will resonate, leading to a smaller amplitude when they do - they are therefore reluctant to break unless a very high amplitude signal is applied to them.

You are looking at £30 - £40 a glass ($50 -$60) from what I have been told by someone who persued this.....

Maybe they told me wrong??

5. May 14, 2005

### zoobyshoe

Yeah, this site says lead crystal glass is best:

Can a very high-pitched scream really shatter glass?