Shatter a glass using sound waves! Classes Used: Phys 101, 153, 341
This demo requires a function generator, an amplifier, a glass, and a horn speaker. When performing the demo, function generator is attached to the amplifier input, and amplifier output is connected to the horn.
Pre-demo setup to gather information: 0. Use a sound meter and oscilloscope (or the Spectroid app) to get the average resonance frequency by tap/knock the wine glass. 1. Use stand with ping pong ball to catch the vibration in the wine glass. (ball inside the inner glass wall is easier) 2. Put the wine glass on a Styrofoam plate/sheet to avoid vibration spread. 3. Place horn near the Styrofoam plate, try to put the wine glass on the edge of the plate, and near the horn. 4. Connect the function generator to amplifier, then amplifier to horn. Use small amplification, and adjust to the frequency range you tested using sound meter. Increase/decrease the frequency by 1Hz at a time, until you find the peak resonance frequency. Remember this frequency for actual demo for this particular wine glass. Tip: due to the nature of the electrical device, the vibration at resonance frequency can be detected within 3-5 Hz range, usually there is a most powerful frequency for vibration, and that is the one you should be looking for.
For actual demo: 0. Remove any tape or labels on the glass. (Labels attached to the bottom is fine) 1. Same electrical setup, though you don't need to test frequency again, since you know it already for that particular wine glass. 2. You don't need the ping pong ball anymore, it was just for testing the small vibration. 3. Different from the testing stage, you need use large amplification/volume. So set the frequency, turn the volume up, and bang! break. (Make sure you use the protective shielding cover.)
Glass Thickness: Maximum 1.1mm, usually model Rona Slovakia 12 Oz bought from Pier 1 Imports, or Viv Red Wine 20oz glasses from Crate and Barrel.
Demo room information