Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography

PLEASE REQUEST DEMOS WELL IN ADVANCE

Due to Physics Building renovations, the lead time to set up demo requests has increased due to the need to transport equipment across campus. Please be kind and let me know well ahead of time what you need.

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Harmonic Motion
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Acoustics
Instruments: Sonometer; Open / Closed Resonance Tube; Resonant tunning fork; video - Dancing Flames (Ruben's Tube); video - Air Driven Organ Pipe; Singing Tubes and Rods; Chladni Figures; video - Breaking a Wine Glass

video - Breaking a Wine Glass

Purpose:

To demonstrate the resonance behavior of a wine glass.

Procedure:

DEMO VIDEO DOWNLOAD w/ sound / 1920x1080 / 24.19Mb/s / 583MB size
DEMO VIDEO DOWNLOAD w/ sound / 854x480 / 5.69Mb/s / 148MB size

DEMO VIDEO DOWNLOAD / no audio / 1920x1080 / 24.19Mb/s / 246MB size
DEMO VIDEO DOWNLOAD / no audio / 854x480 / 5.69Mb/s / 65MB size

Set the wine glass in front of the horn driver (speaker). The approximate resonance frequency of the glass will be written on the base of the glass and the PASCO function generator will be set to that frequency. Set the classroom projector to the appropriate camera which allows the class to view the glass from above. Turn ON the strobe lamp.

1. First show how the glass moves at resonance by setting the function generator amplitude to a "low" setting such as 2 to 3 Volts. If needed, adjust the strobe lamp frequency to slow down or speed up the apparent motion of the lip of the wine glass.

2. Now try to break the glass at resonance by increasing the amplitude of the function generator. If the glass does not break, then gently sweep the frequency up or down. If glass still does not break, try another glass.

Hints:

The glass frequencies will need to be predetermined ahead of time of the demo.
If one increases the amplitude of the sound slowly, you might max out and not break the glass. A couple hints that may help break the glass:
1. while at resonance, start out at low amplitude, then increase the amplitude quickly to help it break
2. at higher amplitude, gently vary the frequency
Some currently manufactured wine glasses that break OK: Crystalex CZ Viola Burgundy 570ml.
Some wines glasses that broke in the past, but are no longer breakable: Luigi Bormioli Crescendo 20 oz. Bordeaux or Bourgogne, Libbey® Occasions 17 1/2-Ounce White.
Some horns we have used: 75 Watt or 100 Watt.

Reference:
A.P. French, "A study of wineglass acoustics", American Journal of Physics, 51, 688 (1983).