Jacob Swett, a senior from Raymore, Missouri, and current president of the Missouri State University chapter of the Society of Physics Students (SPS) received the 2008-2009 Marsh W. White award for his project to build a Rubens’ tube.
The American Institutes of Physics solicits proposals from local chapters of the SPS to determine who will win the Marsh W. White awards. These awards are given to the SPS students, as the SPS website states, “to support projects designed to promote interest in physics among students and the general public.” The awards, which were first made in 1975, were named in honor of Dr. Marsh W. White for his long years of service to Sigma Pi Sigma, the national physics honor society that is part of the SPS.
“I wrote the grant to SPS national to secure funds for a project to promote physics outreach at Missouri State and the surrounding area,” said Swett. “I specifically wrote the grant for a Rubens’ tube because I felt that its unique nature of combining fire with sound would appeal to the average person while also making them interested in physics.”
A Rubens’ tube is a physics experiment that shows the relationship between sound waves and air pressure. The actual tube is made from a piece of pipe with holes that are half-inch deep, cut in equal intervals along the pipe. The pipe is sealed at both ends. One end is sealed with a tube which will provide a way for propane to enter the pipe, and the other end is sealed with a rubber membrane that has both a speaker and a frequency generator attached to it. A CD player can also be used to perform this experiment.
The holes at the top of the tube allow gas to escape, providing the flames needed to show the relationship between the sound waves and air pressure. When the frequency generator and the speaker are turned on, the flames will create a standing wave. More gas will escape from higher-pressure areas in the tube and create higher flames, while lower-pressure areas will lead to lower flames.
The Ruben’s tube will be placed in the physics department inventory to help with recruiting for the department and will be used for demonstrations for students of all ages.