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


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