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Nuclear Decay question without knowing N0 or N ?

  1. May 9, 2012 #1
    Nuclear Decay question without knowing N0 or N ??

    1. The problem statement, all variables and given/known data
    Ok so what I have an Am sample which emits alpha particles at a rate of 70Bq in 1997 and asks for the activity 8 years later (the half life of Am being 432.2 years) I found this to be 69.108 Bq, first of all does this sound right?


    Secondly it asks for the number of nuclei both in 1997 AND 8 years later in 2005 - I have no idea to do this, is there an equation that relates the initial and final nuclei number without knowing either?


    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. May 9, 2012 #2
    Re: Nuclear Decay question without knowing N0 or N ??

    [tex]
    A(t) = A_0 \, \exp(-\lambda \, t)
    [/tex]

    A is activity and is measured in bequerel ([itex]1 \, \mathrm{Bq} = 1 \, \mathrm{s}^{-1}[/itex])
     
  4. May 9, 2012 #3
    Re: Nuclear Decay question without knowing N0 or N ??

    Also, A(t) = λN(t)
     
  5. May 9, 2012 #4
    Re: Nuclear Decay question without knowing N0 or N ??

    Yeah I sort of understand that it's just I don't know how to apply my answer for activity to find the nuclei number before and after
     
  6. May 9, 2012 #5
    Re: Nuclear Decay question without knowing N0 or N ??

    see post #3.
     
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