• Question: Is the air pressure inside a bubble the same as the air pressure outside the bubble? Does it depend on the volume of liquid that makes up the surface of the bubble?

    Asked by doppler to Adam, Sheila, Suzie on 24 Mar 2011 in Categories: .
    • Photo: Adam Tuff

      Adam Tuff answered on 23 Mar 2011:

      Air pressure is always greater inside the bubble than outside – it doesn’t continue to expand and expand because there is alo a surface tension created by the bubble film, which minimises the volume of the bubble – the pressure is proportional to the density of the liquid that makes up the bubble film (and the radius of the bubble).

    • Photo: Suzie Sheehy

      Suzie Sheehy answered on 24 Mar 2011:

      hi there, another good question 🙂
      The surface of the bubble has surface tension so is trying to contract and squeeze down the air inside. This means the pressure inside the bubble is slightly higher than the air pressure outside – the bubble’s size depends on the surface tension of the surface (soapy liquid) and it stops shrinking when it reaches a point that it would pop if it got any smaller!

    • Photo: Sheila Kanani

      Sheila Kanani answered on 24 Mar 2011:

      The bubble has slightly higher pressure inside, because the liquid shell is trying to contract and the inside of the bubble is pushing back on it.
      The shape of it does change its strength and thus its ability to withstand popping, it there is a weakness in its shape it will pop too. So yes, it does depend on the volume of liquid that makes up the bubble’s surface.

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