Posted by Nezz on Monday, July 16, 2012 at 4:50am.
What fraction of the original activity of a radioactive substance will remain at the end of halflife?

Science  Elena, Monday, July 16, 2012 at 6:07am
Halflife T is the time during which the number of decaying species decreases by half
Decay Law
N=Nₒ•exp(λ•t)
Decay constant
λ=ln2/T.
Halflife T is the time during which the number of decaying species decreases by half
If t=T, then
N= Nₒ•exp(λ•T)= Nₒ•exp(ln2•T /t)= Nₒ•exp(ln2)=0.5•Nₒ.
Activity of a given amount of radioactive material is calculated as the decay constant (related to the halflife T) multiplied by the number of radioactive nuclei
A=λ•N, Aₒ=λ•Nₒ.
A=Aₒ exp(λ•T) =>
λ•N= λ•Nₒ • exp(λ•T).
A=Aₒ/2.