PURPOSE: To demonstrate standing wave resonances in an open tube.
DESCRIPTION: A flexible, plastic tube has a series of corrugated ribs. Hold the tube by one end and swing it around to produce resonant frequencies of the tube. The velocity at one end of the tube will cause air to be sucked in by the Bernoulli effect. The corrugated ribs cause the in flowing air to vibrate. The length of the tube determines the resonance frequencies of the harmonics for the cavity.
Keep both ends open and free for the flow of air. Increase the speed of the
rotation to raise the frequency of the harmonic. Up to seven harmonics can be produced,
illustrating the notes of the overtone series. The fundamental can only be produced by
blowing gently into one end.
EQUIPMENT: Bloogle, as photographed.
Updated by Jun Qi in 4/5/2000