Question
Physics Question on deccay rate
Two radioactive materials X1 and X2 have decay constants 10λ and λ respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of X1 to that of X2 will be 1/e after a time
A
1/10λ
B
1/11λ
C
11/10λ
D
1/9λ
Answer
1/9λ
Explanation
Solution
Nx2(t)Nx1(t)eI
N0e−λtN0e−10λt=eI
(Initially, both have same number of nuclei say N0)
or e=eλt/e−10λt or e=e9λt
or $$9\lambda t=1 or t=9λ1