JIPMER Jipmer Medical Solved Paper-1995

  • question_answer
    During mean life of radioactive element the fraction that disintegrates is:            

    A)              \[e\]                                        

    B)             \[\frac{1}{e}\]      

    C)                    \[\frac{e-1}{e}\]          

    D)                                    \[\frac{e}{e-1}\]

    Correct Answer: C

    Solution :

    The relation for the ratio of disintegration and initial values of a radioactive element is \[\frac{N}{{{N}_{0}}}={{e}^{-\lambda T}}\] and average life \[(t)=\frac{1}{\lambda }.\] Hence, \[\frac{N}{{{N}_{0}}}={{e}^{-\lambda \cdot \frac{1}{\lambda }}}={{e}^{-1}}\] Thus disintegrated amount \[=1-\frac{N}{{{N}_{0}}}=1-{{e}^{-1}}=1-\frac{1}{e}=\frac{e-1}{e}\]


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