I filled a 6-foot long and 3-inch diameter galvanized steel tube with propane gas using a propane torch valve. On one end of the tube a speaker emitted frequencies from a frequency generator program loaded on a laptop computer. A plastic stopper in the other end set the length of the Ruben's Tube. Gas coming out of one-sixteenth of an inch holes drilled one inch apart along the top of the tube became flames when lit. Fine-tuning the frequencies generated on the computer allowed me to use the antinodes (peaks) and nodes (valleys) in the flames to determine the frequencies that resonated in my tube.
The resonating frequencies determined in my experiment closely matched the calculated frequencies. When the longitudinal sound waves traveled through the tube, bounced off the end and returned, I was able to observe the compressions and rarefactions of the waves by the effect of the pressure on the gas. I was able to see standing waves clearly and determined frequencies for the fifth through tenth harmonics.
By using the scientific method and paying close attention to the many different variables that might have thrown off my results, I was able to experimentally confirm the resonating frequencies calculated for the tube. The knowledge gained in this experiment is useful in the design of musical instruments such as organ pipes.
This project is to calculate and measure resonate frequencies observed in standing waves created by the constructive and deconstructive interference of sound waves in a Ruben's Tube.
Science Fair Project done By Gabriel H. Burnworth