RAJASTHAN ­ PET Rajasthan PET Solved Paper-2004

  • question_answer
    Half-life of a radioactive element is T and its decay constant is \[\lambda \], then

    A)  \[\lambda T=1\]           

    B)  \[\lambda T=1/2\]

    C)  \[\lambda T={{\log }_{e}}2\]     

    D)  \[\lambda =-{{\log }_{e}}2T\]

    Correct Answer: C

    Solution :

     The number of radioactive atoms after time t\[N={{N}_{0}}{{e}^{-\lambda t}}\] where\[{{N}_{0}}=\]number of atoms initially if\[t=T,\]then \[N={{N}_{0}}/2\] \[\therefore \] \[\frac{{{N}_{0}}}{2}={{N}_{0}}{{e}^{-\lambda T}}\] \[{{e}^{\lambda T}}=2\] \[\lambda T={{\log }_{e}}2\]


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