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The count rate of a Geiger Muller counter for the radiation of a radioactive material of half-life 30 minutes decreases to 5 sec -1 after 2 hours. The initial count rate was (a) 20 sec -1 (b) 25 sec -1 (c) 80 sec -1 (d) 625 sec -1



The count rate of a Geiger Muller counter for the radiation of a radioactive material of half-life 30 minutes decreases to 5 sec-1 after 2 hours. The initial count rate was    


        (a)    20 sec-1    


(b)    25 sec-1


        (c)    80 sec-1


        (d)    625 sec-1


Grade:10

1 Answers

Navjyot Kalra
askIITians Faculty 654 Points
10 years ago

(c)

Half-life = 30minutes; Rate of decrease (N) = 5 per second and total time = 2 hours = 120 minutes.

Relation for initial and final count rate

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