Rubens' Tube

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A Rubens' Tube setup
A Rubens' Tube setup

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.

Contents

[edit] Overview

A length of pipe is perforated along the top and sealed at both ends - one seal is attached to a small speaker, the other to a supply of a flammable gas. The pipe is filled with the gas, and the gas leaking from the perforations is lit. When the speaker is turned on, the pressure changes caused by the sound waves will cause the flames to heighten in some areas and to lower in others. If a constant frequency is used, it is possible to determine the wavelength by simply measuring with a ruler.

[edit] History

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 1905, 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. [1] [2] [3]

Measuring the wavelength of a tone played into the device.
Measuring the wavelength of a tone played into the device.

[edit] 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.[4]
This display is also found in Physics departments at a number of Universities.[5]

[edit] References

  1. ^ Philosophical Transactions of the Royal Society of London. "Series A, Containing Papers of a Mathematical or Physical Character", Vol. 230, pp. 413-445 (1932)
  2. ^ The Flame Tube - ENGLISH TRANSLATION. Retrieved on November 8, 2006.
  3. ^ Luehrs Waterwave Englisch (.doc format). Retrieved on November 8, 2006.
  4. ^ The Exploratory - Exhibits. Retrieved on November 6, 2006.
  5. ^ Oscillation & Waves. Retrieved on November 8, 2006.

[edit] External links

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