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Breaking Glass with Sound

Rubbing the rim of a wine glass with a wet finger will cause it to resonate at its resonant frequency. The glass is placed in front of a speaker playing a sine wave, created by the function generator, of this same frequency. When the amplitude is turned up, we can see by shining a strobe light at the glass that this resonant frequency causes it to oscillate. When the glass becomes too stressed, it will shatter, which we see very clearly on high speed video.

A few things to note: The scrolling effect seen in the strobe light footage is caused by interference between the strobe light frequency and the video camera frame rate. Also, the real oscillations of the glass are much faster than they appear in the strobe footage. Setting the frequency of the strobe light can make them appear much slower so that we can see the oscillations in real time without the help of high speed video.

We would like to thank Dr. Jim Bales of the MIT Edgerton Center for helping us with the high speed video recording, and for the use of the equipment. The high speed camera used here is a Phantom v7.1, donated by the manufacturer Vision Research, Inc.

Comments (1)

First, I would say you need a quality crystal wine glass. Next you need to determine that individual glass’s natural resonance, i.e., the freq,. that it vibrates the easiest at. An oscilloscope would help. Next you need a quality freq. generator to reproduce that exact freq. and some quality transducers (speakers) that are not going to get burnt up playing back a loud sustained freq. or sine wave., not to mention a pretty awesome amplifier. really interesting facts

Posted almost 6 years by danny4u

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MIT Department of Physics Technical Services Group

MIT Department of Physics Technical Services Group

Category: Science | Updated almost 2 years ago

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May 27, 2009 11:18
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