CPB Budapest 2017
Radioactive Decay: Activity A
Experimentally , it is found that the activity, A(t), at any instant of time t is directly proportional to the number, N(t), of the radioactive parent nuclei present at that time: )t(N )t(A λ=
where λ is the decay constant. Combining the two equations:
)t(dN λ=
t dN )(
and we have )t(N )t(A λ= −
)( −=
)t(N
tA
dt
dt
Integrating this differential equation results to:
=
λ−
exp( N )t(N 0
)t
where N
0 is the (initial) number of radioactive nuclei at t=0, i.e. N 0
=N(0).
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