Question

for a radio active element the amount of element decaying in time equal t
o the mean life is​

Answer 1

Answer:

the mean life of a radioactive sample is 1 by lambda.

Answer 2

Answer:

$=1-\frac{1}{e}$

Explanation:

The mean life of a radioactive sample is the ratio of total lifetimes of all individual nuclei to a total number of nuclei present in sample.

Now,

Numbers of atoms disintegrated,

$N=N_{0}\left(1-e^{-\lambda t}\right) \frac{N}{N_{0}}=1-e^{-\lambda t}$

At t= one mean life =$1 / \lambda$

$\frac{N}{N_{0}} =1-e^{-1}$

$=1-\frac{1}{e}$

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