Properties Of Solids And Liquids Question 351
Question: The work done in increasing the size of a soap film from 10 cm× 6 cm to 10 cm × 11 cm is 3 ×10-4 joule. The surface tension of the film is[MP PET 1999; JIPMER 2001, 02; MP PMT 2000; AIIMS 2000]
Options:
A) $ 1.5\times {{10}^{-2}}N/m $
B) $ 3.0\times {{10}^{-2}}N/m $
C) $ 6.0\times {{10}^{-2}}N/m $
D) $ 11.0\times {{10}^{-2}}N/m $
Show Answer
Answer:
Correct Answer: B
Solution:
$ W=T\times \Delta A $ \ $ T=\frac{W}{\Delta A} $
$ T=\frac{3\times {{10}^{-4}}}{2\times (110-60)\times {{10}^{-4}}} $ (Soap film has two surfaces)=$ 3\times {{10}^{-2}}N/m $
