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KVPY Sample Paper KVPY Stream-SX Model Paper-24

  • question_answer
    Using a nuclear counter the count rate of en particles from a radioactive source is measured. At \[t=0\] it was 1600 counts per second and \[t=8\] seconds it was 100 counts per second. The observed, as counts per second, at. \[t=6\] second is  close to:

    A) 200

    B) 150

    C) 400      

    D) 360

    Correct Answer: A

    Solution :

    In 8 seconds count rate becomes \[\frac{1}{16}\]times.
    \[\therefore \]      4 half lives \[=8s\]
                1 half life \[=2s\]
    In \[6s\]or 3 half lives, count rate\[=\frac{1600}{{{2}^{3}}}=200.\]


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