Physics at the University of Virginia
Academics People Research Announcements Facilities Adminstration Home Updates

Return to Demo Lab Homepage

Al Tobias (wat4y) - Office: Gibson S123 & Physics 218, (434) 924-0538

Physics Demo Manual

Demonstrations are cataloged according to PIRA Bibliography


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.

Choose a Topic or Enter a keyword to search:
I cannot find what I want!

You have selected the following Demos:
  • None Selected

Choose a subtopic:
(Clicking a green button will add that demo to your list)
 Harmonic Motion
 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

Open / Closed Resonance Tube


Demonstrate the acoustic resonance effect in air columns of different length.


The Economy Resonance Tube instruction manual describes some details on how to use the tube. Each tube is about 1.3m long, but can slide to different lengths. While in closed tube configuration, experiments can be done with tube lengths as short as 3cm.

Set up the resonance tube in horizontal orientation on its pair of black plastic stands. Place a PASCO open speaker an inch away from the tube opening and connect the speaker to a PASCO function generator.

The resonance tube apparatus can be used as a completely open end tube (open configuration) or with a plug (closed configuration).

Change the speaker frequency and/or tube length to hear the resonances.

Open configuration tube resonates at about 120Hz. The loudest resonances for the closed configuration seems to be between 200 and 400 Hz.

The setup comes with a built-in ruler that allows quantitative measurements as well.


Open Tube
  • 1st Harmonic: f=v/2L
  • 2nd Harmonic: f=v/L
  • 3rd Harmonic: f=3v/2
Closed Tube
  • 1st Harmonic: f=v/4L
  • 3rd Harmonic: f=3v/4L
  • 5th Harmonic: f=5v/4L


  • Speaker
  • Resonance Tube
  • Wave Generator