Date: Mon, 24 May 1999 21:44:48 -0400

Author: Gordon Shepherd

Subject: Re: breaking glass with sound


I saw a very simple display put on by the Discovery Center in Charlotte, NC.
>From my fuzzy memory it consisted of a sheet of glass around 5"x20",
supported in the horizontal position at the 1/4 and 3/4 positions of its
length so that it could bend and vibrate with the support points at the
natural nodes. A speaker was placed under the middle of the glass and
connected to an oscillator/amplifier and the entire apparatus was under a
transparent plastic case for obvious safety reasons. Adjusting the
oscillator to the resonant frequency and increasing the amplitude, I
believe, was also accompanied with a strobe light showing how much the
generally accepted "rigid" glass was actually bending. When the energy was
sufficient the glass broke. This might be a little less expensive than the
beaker but each demo has its virtues. Watching the "rigid" beaker bend and
was amazing to me. Has anyone seen or used a demo similar to the glass sheet
one I just described?
Gordon Shepherd


> I have some students who want to break glass with sound. Has anyone had
> any luck setting this up reliably?
> Digby Willard
> Central High School
> St. Paul, MN