Analysis of a Deflating Soap Bubble

Thomas Schenck, Jacob Heberling, and Sarah Sleyman '08
Advisor: David Jackson  

This project was designed to understand how the radius of a deflating soap bubble changes with time.  A syringe attached to a large-diameter tube was used to blow the bubble and a small-diameter tube was used to deflate the bubble.  A precision manometer was connected to the system to measure the pressure difference between the inside and outside of the bubble.  The figure below shows a schematic of the experimental setup.

The surface tension was found from the Young-Laplace equation by measuring the differential pressure for a number of different bubble sizes.  Capturing the deflating bubble with a video camera, we used image analysis software to determine the bubble radius as a function of time.  At this point, every parameter was experimentally measured and could be compared to theory.  The figure below shows the incredible agreement between theory and experiment.

More details on this project can be found in an article published in the American Journal of Physics (and featured on the cover of the Oct. 2010 issue).  Simply click the image below.