From key@physics.utoronto.ca Wed Mar 12 19:28:15 2008
Date: Wed, 12 Mar 2008 19:28:15 -0400 (EDT)
From: Anthony Key <key@physics.utoronto.ca>
To: key@physics.utoronto.ca
Subject: Re: PHY138 Question (fwd)


Subject: Re: PHY138 Question

Hi - I'm not sure which problem you are grappling with - in future let me
know exactly. However, if you know the activity at two different times, say
t1 and t2, you can calculate the decay constant, since you know that the
activity at time t2 is given in terms of the activity at time t1 by the
usual equation -

R(t2) = R(t1)*exp{(t2-t1)*lambda} - solve for lambda by taking logs of both
sides (lambda =ln2/{half-life}).  This is the algebraic method - I showed
the graphical method in class today.

Did this answer your question?

TonyK


>  Hello,
>  I am trying to calculate the half life of a radioactive tracer (in one of
>  the mastering physics problems).  I understand how to work with the
>  questions when you are given the half-life, but I am not clear on how to
>  work out the half life from the given the quantities.  Is there a simple
>  step-by-step method to make this process less confusing.  I appreciate
>  any
>  feedback.
>  Thanks so much,