Rubens' Tube

The Rubens' tube, also known as the Standing wave flame tube, or simply flame tube, is a physics experiment demonstrating a standing wave. It shows the relationship between sound waves and air pressure.

Overview

A length of pipe is perforated along the top and sealed at both ends - one seal is attached to a small speaker or frequency generator, the other to a supply of a flammable gas(propane tank). The pipe is filled with the gas, and the gas leaking from the perforations is lit. If a constant frequency is used, a standing wave can form within the tube. When the speaker is turned on, the standing wave will create higher and lower pressure points along the tube. Where there is higher pressure due to the sound waves, more gas will escape from the perforations in the tube, and the flames will be higher at those points. In these cases, it is possible to determine the wavelength by simply measuring with a ruler.

History

John Le Conte discovered in 1858 that flames were sensitive to sound. In 1862 Rudolph Koenig showed that the height of a flame could be affected by transmitting sound in the gas supply, and the change as time passes could be displayed with rotating mirrors. August Kundt, in 1866, demonstrated an acoustical standing wave by placing seeds of lycopodium or cork dust in a tube. When a sound was made in the tube, the material inside lined up in nodes and antinodes in line with the oscillation of the wave, creating a standing wave. Later that century, Behn showed that small flames could be used as sensitive indicators of pressure. Finally, in 1904, using these two important discoveries, Heinrich Rubens, whom this experiment is named after, took a 4-metre-long tube and drilled 200 small holes into it at 2 centimeter intervals, and filled it with a flammable gas. After lighting the gas (whose flames all rose to near-equal heights), he noted that a sound produced at one end of the tube would create a standing wave, equivalent to the wavelength of the sound being made. [Verhandlungen der Deutschen Physikalischen Gesellschaft, Nr.24 (30 Dec 1904) pp. [http://www.instructables.com/files/deriv/FX7/DXFT/F5Y3KW37/FX7DXFTF5Y3KW37.LARGE.jpg351] , [http://www.instructables.com/files/deriv/F8S/YU2I/F5Y3KW39/F8SYU2IF5Y3KW39.LARGE.jpg352] , [http://www.instructables.com/files/deriv/FPP/LIBC/F5Y3KW35/FPPLIBCF5Y3KW35.LARGE.jpg353] , 354 "Stehende Schallwellen durch Manometerflammen, (Demonstrated by Heinrich Rubens, December, 8th 1904 )" [http://www.instructables.com/id/S9QLGKXF5R8MTGP/ via instructables] ] . [Annalen der Physik, vol. 322, Issue 6, pp.149-164 [http://www.weltderphysik.de/intern/upload/annalen_der_physik/1905/Band_322_149.pdf Flammenröhre für akustische Beobachtungen ] , H. Rubens, O. Krigar-Menzel (1905)] [Philosophical Transactions of the Royal Society of London. " [http://links.jstor.org/sici?sici=0264-3952%281932%29230%3C413%3AOTGAGB%3E2.0.CO%3B2-9&size=LARGE Series A, Containing Papers of a Mathematical or Physical Character] ", Vol. 230, pp. 413-445 (1932)] [cite web|url=http://www.fysikbasen.dk/English.php?page=Vis&id=6|title=The Flame Tube - ENGLISH TRANSLATION |accessdate=November 8|accessyear=2006] [cite web|url=http://web.archive.org/web/20040724131501/http://www.science-on-stage.de/fileadmin/Materialien/CD_POS3/Luehrs_waterwave_englisch.doc|title=Luehrs Waterwave Englisch (.doc format)|accessdate=November 8|accessyear=2006] O. Krigar-Menzel assisted Rubens with the theory.

Public displays

A Rubens' Tube was on display at "The Exploratory" in Bristol, England until it closed in 1999, at which time the exhibit was moved to the "@-Bristol" museum. [cite web|url=http://www.exploratory.org.uk/exhibits/sound.htm|title=The Exploratory - Exhibits |accessdate=November 6|accessyear=2006]
This display is also found in Physics departments at a number of Universities. [cite web|url=http://pirt.asu.edu/detail_3.asp?ID=1462&offset=175|title=Oscillation & Waves |accessdate=November 8|accessyear=2006]

References

External links

* [http://www.youtube.com/watch?v=oPWucNgN8TQ Detailed Video] including sound board and microphone.
* [http://www.vuw.ac.nz/scps-demos/demos/Light_and_Waves/SoundFlames/SoundFlames.htm Experiment notes] , video & detailed analysis
* [http://www.fysikbasen.dk/English.php?page=Vis&id=6 Flame tube] setup and explanation of effects
* [http://www.physics.umd.edu/lecdem/services/demos/demosh3/h3-17.htm Brief setup] guide
* [http://www.physics.isu.edu/physdemos/waves/flamtube.htm Classroom] setup guide
* [http://web.archive.org/web/20040724131501/http://www.science-on-stage.de/fileadmin/Materialien/CD_POS3/Luehrs_waterwave_englisch.doc Information] on Rubens' original design (in .doc format)
* [http://groups.physics.umn.edu/demo/old_page/demo_gifs/3D30_50.gifImage] showing setup
* [http://physicslearning.colorado.edu/website_new/Common/ViewDemonstration.asp?DemoCode=3D30.50 General] information
* [http://pirt.asu.edu/detail_3.asp?ID=1462&offset=175 Experiment setup] , under "Links" heading & very nice photo illustrating this experiment
* [http://www.richdunajewski.com/videos/YHpovwbPGEoo] , home video showing various tones and music being played (2:51)
* [http://www.youtube.com/watch?v=cootexkMmrY] , Ruben's Tube performance by Alyce Santoro