3D40.55 - Shattering the Wine Glass
This demonstration drives a wine glass acoustically until it shatters.
The demonstration lies on a cart that is ready to be rolled out for lecture. Make sure there is ear protection for the lecturer and enough (2-3 per class section) tuned glasses to get through the lecture.
DO NOT USE THE RADIO SHACK AMPLIFIER
To begin, turn on the video of the wine glass to the main projector and turn down the room lights. Be sure to warn the students that the sound will be loud and to plug their ears if needed. The next step is to tune the driving signal generator to the resonant frequency of the wine glass.
When set, turn the amplitude of the signal on the amplifier until the power meter readys an output of 0.1W. At this point, it is important to adjust the driving frequency of the signal generator while watching the oscilloscope to reach the highest peak (When the glass resonantes at the driving frequency, the piezo feedback pad that the glass resides on will register this as an increase in amplitude on the oscilloscope.).
Once you feel that you have found the maximum amplitude oscillation of the glass, then adjust the strobe signal generator 2-6 Hz off of the resonant frequency that the glass is set. At this point, you can blow up the wine glass by increasing the amplitude on the amplifier until the glass shatters.
**Be sure to warn your students once more to cover their ears before you turn up the amplitude volume to shatter the glass**