Re: [Phys-l] models of radioactivity

[Jack Uretsky <jlu@hep.anl.gov>]

The time dependence of a population of decaying atoms is assumed to follow 
the Poisson law
	N(t) =N(0)e^{-pt).
	the half-lkife T' is defined to follow N(T') =N(0)/2, or
	e^{-pT'} =1/2
Taking the ln of each side of the last equation gives:
	pT' =ln2, which leads immediately to the quoted equation.

On Sat, 18 Apr 2009, Brian Whatcott wrote:

> John Denker wrote:
> > On 04/17/2009 10:25 PM, Hugh Haskell wrote:
> >
> >
> > > we know that half-life (T) can be
> > > expressed as
> > >
> > > 	T = (ln 2)/p		(1)
> >
> > What do you mean by "we", Kemosabe?
> We?
> The folks at MIT giving an introduction to modeling radio-active
> half-life, for example.
> See this version
> <http://www-math.mit.edu/~djk/calculus_beginners/chapter12/section02.html>
>
> Hugh is in fact illustrating a comparable example to the difference
> between compounding capital at time intervals, say weekly, monthly,
> quarterly etc., and
> compounding capital continuously. This is a standard introductory
> element of
> teaching exponential versus discrete time models, I thought?
>
> Brian W
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