This demonstration shows acoustic standing waves. The apparatus is a long aluminum tube with holes in it. A speaker is attached at one end. The tube is filled with gas and flames lit from the gas escaping the holes in the tube. As sound is played through the speaker, the pressure differences create changes in the flame height. By using a function generator, standing waves can be seen. Music can also be played.
* Equipment seen in the video may vary from equipment used in ND Demonstrations. See information and images below for ND equipment and setup.
Setup:
Place the Rubens tube apparatus on two lab tables pushed together. (It is too long for one lab table.)
Attach the hose to the Rubens tube and the gas supply.
Attach the function generator or music source to the power amplifier and the power amplifier to the speaker using banana cables.
Turn on the gas supply and wait a few seconds. Light the gas escaping from the holes. Make sure all the holes are lit. Adjust the gas supply so that flames are a few inches long. Too little gas and the flames will easily go out. Too much gas and the waves can be difficult to see.
Turn on the sound and adjust the volume so that waves are visible. If the sound is too loud, the flames will go out. If the sound is too soft, the wave will not be visible.
Once you are done, turn off the gas and the flames will go out. Evacuate the tube with air if possible.
Be careful, the tube will be hot.
Notes:
The classroom gas lines may need to be turned on using the knob underneath the sink.
Courses Used In:
Coming Soon
Discussion and Polling Questions:
Coming Soon
Equipment Needed
Rubens Tube Apparatus with Connection Hose
Power Amplifier
2 - 4 Banana Cables
Function Generator
Gas Source
Lighter
Computer or Phone with Music (Optional) and Hook-Up Cable