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Two soap bubbles are touching each other.Radius of curvature at point of contact ?

  1. Mar 2, 2012 #1
    Two soap bubbles of radius r and R are in touch find the radius of curvature of their point of contact?
    (Both bubbles are touching each other with their external surfaces)

    I have no idea about this question. can you please try to help>
     
  2. jcsd
  3. Mar 2, 2012 #2
    Re: Two soap bubbles are touching each other.Radius of curvature at point of contact

    What do you know about surface tension?
     
  4. Mar 2, 2012 #3
    Re: Two soap bubbles are touching each other.Radius of curvature at point of contact

    No info about surface tension. even answer is in terms r and R.
    If you think it can't be done without data related to surface tension then assume that to be S.
    answer in book may be wrong...
     
  5. Mar 2, 2012 #4
    Re: Two soap bubbles are touching each other.Radius of curvature at point of contact

    So do you know the answer?
     
  6. Mar 2, 2012 #5
    Re: Two soap bubbles are touching each other.Radius of curvature at point of contact

    yeah;
    It's answer is given in book. But book doesn't provide procedure.
     
  7. Mar 2, 2012 #6
    Re: Two soap bubbles are touching each other.Radius of curvature at point of contact

    Surface tension does come into it but in this problem it cancels out.Have you studied surface tension?
     
  8. Mar 2, 2012 #7
    Re: Two soap bubbles are touching each other.Radius of curvature at point of contact

    yes. (I have read surface tension,angle of contact, capillarity, pressure inside a soap and liquid bubble,change in energy when surface expand or collapse).
    How do you approach to this question?
     
  9. Mar 2, 2012 #8
    Re: Two soap bubbles are touching each other.Radius of curvature at point of contact

    Good,so you should know that the pressure inside a bubble is greater than the pressure outside.Now apply that pressure difference formula to the bubbles when they are in contact.There are three radii of relevance r,R and the common radius over their area of contact.
     
  10. Mar 2, 2012 #9
    Re: Two soap bubbles are touching each other.Radius of curvature at point of contact

    Wow!
    great;
    i have got the answer.
    thanks for helping me.
     
  11. Sep 12, 2012 #10
    Re: Two soap bubbles are touching each other.Radius of curvature at point of contact

    if u have understood pls help me too i havent understand nythin abt the common radii
     
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