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Exponential Decay


Exponential decay is the decrease in a quantity N according to the law

 N(t)=N_0e^(-lambdat)
(1)

for a parameter t and constant lambda (known as the decay constant), where e^x is the exponential function and N_0=N(0) is the initial value. Exponential decay is common in physical processes such as radioactive decay, cooling in a draft (i.e., by forced convection), and so on. Exponential decay is described by the first-order ordinary differential equation

 (dN)/(dt)=-lambdaN,
(2)

which can be rearranged to

 (dN)/N=-lambdadt.
(3)

Integrating both sides then gives

 ln(N/(N_0))=-lambdat,
(4)

and exponentiating both sides yields the functional form (1).


See also

Damped Exponential Cosine Integral, Exponential Function, Exponential Growth, Malthusian Parameter, Population Growth

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Cite this as:

Weisstein, Eric W. "Exponential Decay." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/ExponentialDecay.html

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