JEE Main & Advanced Physics Nuclear Physics And Radioactivity Question Bank Self Evaluation Test - Nuclei

  • question_answer
    For a radioactive sample the counting rate changes from 6520 counts/minute to 3260 counts minute in 2 minutes. Determine the decay constant.

    A)  1.78 per sec

    B)   0.78 per sec

    C)  2.78 per sec

    D)   5.78 per sec

    Correct Answer: D

    Solution :

    [d] at time  \[t=0;\]  \[{{A}_{0}}=\frac{d{{N}_{0}}}{dt}\] \[\frac{A}{{{A}_{0}}}=\frac{dN/dt}{d{{N}_{0}}/dt}=\frac{3260}{6520}\] or   \[\lambda =\frac{2.303}{t}\log \frac{{{A}_{0}}}{A}=\frac{2.303}{2\times 60}\log 2\] \[=5.78\,\,per\,\,\sec \]


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