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NEET Sample Paper NEET Sample Test Paper-57

  • question_answer
    Consider a soap film on a rectangular frame of wire of area\[4\times 4\,c{{m}^{2}}\]. If the area of the soap film is increased to \[4\times 5\,c{{m}^{2}}\], the work done in the process will be:(surface tension \[=3\times {{10}^{-2}}N/m\])

    A) \[12\times {{10}^{-6}}J\]                     

    B) \[24\times {{10}^{-6}}J\]

    C) \[60\times {{10}^{-6}}J\]                     

    D) \[96\times {{10}^{-6}}J\]

    Correct Answer: B

    Solution :

    [b] \[Area=16\times {{10}^{-\,4}}\,4{{m}^{2}}\] \[Are{{a}_{2}}=20\times {{10}^{-4}}{{m}^{2}}\] \[\Delta \,A=(20\times {{10}^{-4}}-16\times {{10}^{-4}})\,\] \[\Delta \,A=4\times {{10}^{-4}}{{m}^{2}}\] Work done \[=2T\text{ }\Delta A\] \[\therefore \] ['2' for two film front & back side] \[=2\times 3\times {{10}^{-2}}\times 4\times {{10}^{-4}}\] \[=24\times {{10}^{-2}}J\]


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