Consider the situation of the previous problem. Suppose the production of the radioactive isotope starts at t = 0. Find the number of active nuclei at time t.

Let N˳ is the radioactive isotope present at time t=0

N be the radioactive isotope present at time t


And λ be the disintegration constant.


By Law of Radioactivity,



No. of particles decay = N˳-N= N˳ (1- -λt)


As the production starts at t=0.


So,


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