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  1. Emissionspectra's Avatar
    1 02-06-2012  08:41
    • Peer Of The TSR Realm
    • Posts: 1,417
    Activity
    The half life of Radon gas is 3.3*10^5 how long will it take for a sample to decay to 33% of It's initial activity?

    Here's what I've done so far: A=A_0e^- ^ \lambda ^t
    \lambda= \frac {ln2}{t_\frac {1}{2}}. I then calculated a value of lambda which is 2.10x10^-6, but then how can i calculate t, if i havn't been given the initial Activity?
  2. medicinemm's Avatar
    2 02-06-2012  08:56
    • Full Member
    • Posts: 102
    Re: Activity
    (Original post by Emissionspectra)
    The half life of Radon gas is 3.3*10^5 how long will it take for a sample to decay to 33% of It's initial activity?

    Here's what I've done so far: A=A_0e^- ^ \lambda ^t
    \lambda= \frac {ln2}{t_\frac {1}{2}}. I then calculated a value of lambda which is 2.10x10^-6, but then how can i calculate t, if i havn't been given the initial Activity?
    If it decays to 33%, I think A/A_0 = 0.33
    So you know 0.33 =e^- ^ \lambda ^t
    And then you can calculate t because you have lambda.
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  3. Emissionspectra's Avatar
    3 02-06-2012  09:07
    • Peer Of The TSR Realm
    • Posts: 1,417
    Re: Activity
    (Original post by medicinemm)
    If it decays to 33%, I think A/A_0 = 0.33
    So you know 0.33 =e^- ^ \lambda ^t
    And then you can calculate t because you have lambda.
    Ahhh ok makes sense thanks.
  4. Cora Lindsay's Avatar
    4 02-06-2012  18:32
    • Exalted and Worshipped Member
    • Posts: 927
    Re: Activity
    Please get into the habit of specifying time units, or you'll get very confused.
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