Rubens' tube

The Rubens flame tube is a named after Heinrich Rubens tool for the visualization of standing sound waves.

Construction

Rubens, the flame tube is made of a tube which is provided at its top with many small holes of the same diameter. One end of the tube is closed by a thin membrane M, the other with a movable piston K. Through the inlet opening E is flammable gas such as propane gas, directed into the tube interior, which flows out through the holes on the top and may be ignited.

Operation

Without exposure to noise on the tube first one sees a number of equal-sized flame. If at this point the membrane by a sound source to vibrate, so you can achieve that forms a standing sound wave inside the tube by suitable displacement of the piston. Alternatively, can be varied for fixed tube lengths, the tone frequency. The shape of the standing wave can be seen from the amount of each Gasflämmchen: On the pressure maxima and minima ( pressure antinodes ) burn the flames low, while higher flames are visible at the pressure node (no change of pressure by the standing sound wave). At the conclusion at which the wave is reflected, in theory should sound pressure abdomen ( maximum) appear.

Although the " Rubens flame tube " a very " full effect " demonstration experiment is standing sound waves in the schools is most often used the Kundt's tube, since you do not have to handle with flammable gas with her for visualization.