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Thread: Radioactive decay

  1. February 21st 2011, 10:40 PM #1
    dmbocci
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    Radioactive decay

    Radium-226 has a half life of 1620 years. Find the time period during which a given mass of this material is reduced by one-quarter.

    Q= Ce^-rt should be the right equation?

    Stumped on how to set this up.
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  2. February 21st 2011, 11:45 PM #2
    CaptainBlack
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    Quote Originally Posted by dmbocci View Post
    Radium-226 has a half life of 1620 years. Find the time period during which a given mass of this material is reduced by one-quarter.

    Q= Ce^-rt should be the right equation?

    Stumped on how to set this up.
    Because you are given a half life it is better to work with powers of $$2 rather than $$e. So:

    Q(t)=Q(0)\times 2^{-t/\tau}

    where $$\tau is the half life.

    Now if at time $$t;\ Q(t)=Q(0)/4 we have:

    2^{-t/\tau}=1/4


    CB
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