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JCECE Engineering JCECE Engineering Solved Paper-2013

  • question_answer
    The intensity of gamma radiation from a given source is\[I\]. If on passing through \[36\,\,mm\] of lead its intensity is reduced to\[\frac{I}{8}\], then what will be the thickness of lead which reduces its intensity to\[\frac{I}{2}\]?

    A) \[6\,\,mm\]                       

    B) \[9\,\,mm\]

    C) \[12\,\,mm\]                    

    D)  \[18\,\,mm\]

    Correct Answer: C

    Solution :

    We have,             \[I={{I}_{0}}{{e}^{-\mu x}}\] \[\therefore \]                  \[\frac{1}{8}={{e}^{-4.36}}\] \[\Rightarrow \]                               \[{{\left( \frac{1}{2} \right)}^{3}}={{e}^{-4.36}}={{({{e}^{-\mu x}})}^{3}}\] or                            \[-3\mu x=-36\mu \] \[\Rightarrow \]                               \[x=12\,\,mm\]


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