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Quantum Mind
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Homework Statement
Two soap bubbles of equal radius 'r' coalesce isothermally to form a bigger bubble of radius 'R'. If the atmospheric pressure is P0, find the surface tension of the soap solution.
Homework Equations
Surface energy = surface tension x increase in area (W = T.ΔA)
Excess pressure inside bubble = 4T/R i.e. T = p.R/4
The Attempt at a Solution
Don't know where to start. From the above equation, I thought I can proceed, but I neither know the surface energy nor the surface tension. I also do not know why the term 'p' has been given or how to relate it to the problem.
Probably I should take the area increase as the difference between the total areas of the smaller bubbles and the area of the larger bubble.
Area of smaller bubbles = 2.4∏r2
Area of bigger bubble = 4∏R2
Difference in area = 4∏(R2 - 2r2)
W = T.4∏(R2 - 2r2)
= p.R.4∏(R2 - 2r2)/4
How do I proceed further?