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Manipal Engineering Manipal Engineering Solved Paper-2012

  • question_answer
    A sound has an intensity of\[2\times {{10}^{-8}}\,\,W/{{m}^{2}}\]. Its intensity level in decibels is\[({{\log }_{10}}2=0.3)\]

    A)  23                                         

    B)  3

    C)  43                         

    D)         4.3

    Correct Answer: C

    Solution :

    \[L=10{{\log }_{10}}\left( \frac{I}{{{I}_{0}}} \right)\] \[\therefore \]  \[L=10{{\log }_{10}}\left( \frac{2\times {{10}^{-8}}}{{{10}^{-12}}} \right)\]                                                 \[(\because \,\,{{I}_{0}}={{10}^{-12}}W/{{m}^{2}})\]                 \[L=10{{\log }_{10}}(2\times {{10}^{4}})\]                 \[L=10[{{\log }_{10}}2+{{\log }_{10}}{{(10)}^{4}}]\]                 \[L=10(4.3)\]                 \[L=43\,\,decibel\]


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