The activity of a radioactive sample is measured as N0 counts per minute at t = 0 and N0/e counts per minute at t = 5 minutes. The time (in minutes) at which the activity reduces to half its value is
- e 25
- 5 e 2
- 5 10 2
- 5 e 2
Answer
(4) 5 e 2
Solution
Activity: R = R0 e- t
N0e = N0 e-5
5 = 1, i.e. = 15 min-1
t1/2 = e 2
= 5 e 2 minutes
Answer: (4)