Introduction
Through this experiment, we will observe the interference of sound waves with the help of a flammable gaseous medium. And for performing this experiment, we have already calculated the frequencies that resonate in Ruben’s tube through experimentation, which establishes standing waves.
Basic Building Concept
1. When two dark fringes or two light fringes meet, they create constructive interference.
2. When one bright fringe and one dark fringe meet, it creates a destructive interference.
Aim
To observe the interference of sound waves with the help of a flammable gaseous medium.
Theory
1. Standing wave flame tube and flame tube are the names given to Ruben’s tube.
2. Ruben’s tube is an instrument with the help of which we can demonstrate acoustic standing waves.
3. The gasses that burn in oxidant and ignition sources, such as hydrogen propane, methane, propylene, etc., are called inflammable gasses.
Requirements
1. A six feet tall and three inches in diameter galvanized steel tube
3. Speaker
4. Computer
5. Plastic Stopper
Procedure
Step 1: Using a propane torch valve, fill the galvanized steel tube with propane.
Step 2: Load a frequency generator program on the computer and connect the speaker to it.
Step 3: Connect the side of the tube with the speaker.
Step 4: Attach the plastic stopper on the other end, which will set the length of Ruben’s tube.
Step 5: On the top of the tube, drill a hole of one-sixth of one inch.
Step 6: The gas that comes from this hole, when lit up, becomes flame.
Step 7: The frequencies generated in our computer will help us find the frequency generated in the tube, with the help of antinode, i.e., peaks and nodes, i.e., valleys.
Image Source: Ruben’s Tube
Observation
1. The frequency which we determined in the experiment matches the calculated frequency.
2. When the longitudinal sound waves bounced to the end and returned through the tube, we observed the rarefaction and the compression of the waves through the effect of pressure on the gas.
3. We have clearly observed the standing frequencies.
4. And with the help of the standing frequencies, we determined frequencies for the fifth and the tenth harmonics.
Result
1. We have successfully confirmed the resonating frequencies calculated for the tube through experimentation.
2. For designing musical instruments like organ pipes, we use this knowledge.
Precautions
1. Connect the speaker to the computer properly.
2. The hole created at the top of the tube should not exceed the limit.
3. Lit up the gasses carefully and for a short period of time.
Conclusion
In this experiment, we measured the resonating frequencies in the standing wave created by the destructive and constructive interference of the sound wave in Ruben’s tube.
VIVA Questions With Answers
Q.1 What was the aim of our experiment?
ANS. To observe the interference of sound waves with the help of a flammable gaseous medium.
Q.2 What do you understand by constructive interference?
ANS. When two dark fringes or two light fringes meet, they create constructive interference.
Q.3 What do you understand about destructive interference?
ANS. When one bright fringe and one dark fringe meet, it creates a destructive interference.
Q.4 What do you understand by the term Rubin’s tube?
ANS. Ruben’s tube is an instrument with the help of which we can demonstrate acoustic standing waves.
Q.5 What do you understand by the term inflammable gasses?
ANS. The gasses which burn in the presence of oxidant and ignition sources, such as hydrogen propane, methane, propylene, etc., are called inflammable gasses.
Q.6 Which inflammable gas have we used in this experiment?
ANS. Propane.
Q.7 What have you observed in this experiment?
ANS. The frequency which we determined in the experiment matches the calculated frequency.
Q.8 Where does this knowledge help us?
ANS. This knowledge helps us in making musical instruments like organ pipes.

Saquib Siddiqui is a Mechanical Engineer with expertise in science projects and experiments. Saquib’s work focuses on integrating scientific concepts with practical applications, making complex ideas accessible and exciting for learners of all ages. In addition to his practical work, Saquib has authored several articles, research papers, and educational materials.
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