3B90.10 • Frequency Vacuum
Location: Cabinet 5
Concepts Conveyed:
Instructions/Notes:
Demo staff:
Photo shows the demonstration used at the University of Texas at Austin.
Concepts Conveyed:
- Demonstrating that sound propagation and intensity decrease with reduced air pressure and airflow, becoming almost negligible under low-pressure (near perfect vacuum) conditions.
- The vacuum pump creates an almost perfect vacuum inside the chamber; however, an extremely faint sound may still be heard due to vibrations transmitted through the solid base and container walls, as well as the presence of a small number of residual air molecules.
- Because sound waves require vibrating particles to propagate, limiting the movement of air particles causes the sound to dampen significantly and almost diminish.
- In a perfect vacuum sound would not propagate at all.
Instructions/Notes:
- Open the container (as shown in the left image).
- Turn on the sound by switching on the battery-powered buzzer (the switch is shown in the images above).
- Wear gloves, apply the vacuum grease, close the container.
- Insert the vacuum pipe into the black portion sticking out of the container on top, and turn on the vacuum pipe using the switch (make sure you have connected the vacuum pump to an outlet using the white cable).
- Once the demonstration is complete, turn off the vacuum pump, remove the pipe, open the container and turn off the buzzer switch. Return the setup to its original position.
Demo staff:
- Vacuum grease is located on the vacuum table (pizza table)
Last updated on February 27, 2026