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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.

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 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

Singing Tubes and Rods


To demonstrate standing waves in a corrugated tube, straight tubes, and aluminum rod.


By swinging the corrugated tube at different speeds, different notes can be excited. One can easily hear an octave, fifth, and fourth. The straight tubes are excited by placing the flame of the bunsen burner into the tube about 10-15 cm. from one end. By rubbing in half of an aluminum rod with violin rosin for better friction, holding it in the middle, and stroking it between thumb and forefinger of the other hand, longitudinal standing waves can be produced. These can be made very loud. Also, by holding the rod at a nodal point and striking it sharply in the middle, a transverse standing wave can be made that is very visible.


One can also tab an aluminum rod on the floor if stroking doesn't work. Different pitches can be excited by holding the rod at different (marked or scratched) places.


  • Violin Rosin
  • Aluminum rods
  • Aluminum tubes
  • Bunsen burner
  • Clamp
  • Corrugated tube
  • Stand