of a sample of a radioactive isotope, which will remain after a given time 
has elapsed. The law is exponential: 
where 
is the initial activity and 
is the decay constant. [P9.2]
is: the law which governs the activity of a sample of a radioactive isotope, which will remain after a given time has elapsed. The law is exponential: where is the initial activity and is the decay constant. [P9.2]
See radioactive decay and radioactive decay law.
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