- #1
ubergewehr273
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Homework Statement
Two species of radioactive atoms are mixed in equal numbers. The disintegration constant of first species is ##\lambda## and that of second species is ##\frac \lambda {3}##. After a long time, the mixture will behave as a species with mean life ________.
Homework Equations
##\lambda=\frac{0.693} {t_{1/2}}##
##t_{mean}=\frac{1}\lambda##
The Attempt at a Solution
What I did was to equate the mean life of mixture being the average of the mean lives of the individual species.
$$t_{mean}=\frac{\frac{1} \lambda + \frac{3}\lambda} {2}$$
However in this article https://en.wikipedia.org/wiki/Half-life it says that ##\frac{1} {t{eff}} = \frac{1} {t_{1}} + \frac{1} {t_{2}}## where ##t_{eff}##,##t_{1}## & ##t_{2}## are half lives of mixture, species A and B respectively.