RAJASTHAN PMT Rajasthan - PMT Solved Paper-2009

  • question_answer
    N atoms of a radioactive element emit n-alpha particles per second. The half-life of the element is

    A) \[\frac{n}{N}s\]               

    B)         \[\frac{N}{n}s\]

    C)  \[\frac{0.693N}{n}s\]    

    D)         \[\frac{0.693n}{N}s\]

    Correct Answer: C

    Solution :

    From radioactive decay law,                      \[\frac{dN}{dt}=-\lambda N\] But given, \[\frac{dN}{dt}=-n\]  \[\therefore \]  \[-n=-\lambda N\] or            \[\frac{1}{\lambda }=\frac{N}{n}\]                                                           ? (i) Half-life period\[(T)=\frac{0.693}{\lambda }\]                                      \[=0.693\frac{N}{n}s\].


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