2. Solved Papers
  3. WB JEE Medical

WB JEE Medical WB JEE Medical Solved Paper-2007

  • question_answer
    The counting rate observed from a radioactive source at t = 0 was 1600 count/s and at t = 8 s it was 100 counts/s. The counting rate observed as counts per second at t = 6 s, will be

    A)  400                                       

    B)  300

    C)  250                                       

    D)  200

    Correct Answer: D

    Solution :

                                    The half - life of source \[=\frac{8}{4}=2s\] Now,                     \[R={{R}_{0}}{{\left( \frac{1}{2} \right)}^{n}}\]                                 \[R=1600{{\left( \frac{1}{2} \right)}^{\frac{6}{2}}}\]                                 \[=16000{{\left( \frac{1}{2} \right)}^{3}}\] \[=200\]


You need to login to perform this action.
You will be redirected in 3 sec spinner