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Exponential Decay

A model for decay of a quantity for which the rate of decay is directly proportional to the amount present. The equation for the model is A = A0bt (where 0 < b < 1 ) or A = A0ekt (where k is a negative number representing the rate of decay). In both formulas A0 is the original amount present at time t = 0.

This model is used for phenomena such as radioactivity or depreciation. For example, A = 50e–0.01t is a model for exponential decay of 50 grams of a radioactive element that decays at a rate of 1% per year.

 

 

See also

Exponential growth, half-life, continuously compounded interest, logistic growth, e

 


  this page updated 27-aug-12
Mathwords: Terms and Formulas from Algebra I to Calculus
written, illustrated, and webmastered by Bruce Simmons
NCTM Web Bytes December 2004 Web Bytes March 2005 Web Bytes