A trumpet blows a bubble to demonstrate

the propagation of sound. 

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Teachable Topics
  • Sound and Frequency
  • Music and Oscillations
  • Wave Propogation


Sound waves, unlike light waves, require a medium to move through in order to be heard. This is because sound waves are longitudinal waves, which case the medium the wave is traveling in to compress and expand. As such, sound waves can be considered a collection of pressure waves.

Sound waves are able to travel through all types of matter, and can move from one medium into another. In this demo, the sound waves move through the air in the trumpet, through the thin film of the bubble, and then back into the air around it. When the sound waves travel through the bubble, it causes the molecules in it to compress and expand, causing the bubble to vibrate.  


  • A trumpet
  • Bubble solution 


  • Dip the open end of the trumpet into the bubble solution, making sure there is a bubble formed at the end.
  • Play the trumpet and the bubble on the end should expand. Observe the expansion and the bubble vibrating.

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