CPB Ljubljana 2018 course book

Radioactive Decay: Exponential Law

Multiplying both sides of the equation by the decay constant λ and considering equation, results to the following equation for the activity



exp( N)t(N



)t

)t    exp( N )t(N

0

0

A

t(





)t (N )

Considering the following equation for the activity results:

) t (A



A

exp(

)  t

0

N

(

)t



N

exp(



)t

0

Both these equations present the exponential law of radioactive decay , which states that the number of nuclei that have not decayed in the sample as well as the activity of the sample, both decrease exponentially with time .