Properties Of Solids And Liquids Question 331

Question: Radius of a soap bubble is ‘r’, surface tension of soap solution is T. Then without increasing the temperature, how much energy will be needed to double its radius [CPMT 1991; Pb. PMT 2000; RPET 2001]

Options:

A) $ 4\pi r^{2}T $

B) $ 2\pi r^{2}T $

C) $ 12\pi r^{2}T $

D)$ 24\pi r^{2}T $

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Answer:

Correct Answer: D

Solution:

$ W=8\pi T(R _{2}^{2}-R _{1}^{2})=8\pi T[{{(2r)}^{2}}-{{(r)}^{2}}]=24\pi r^{2}T $



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