IEVref: | 103-05-26 | ID: | |

Language: | en | Status: Standard | |

Term: | time constant | ||

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Symbol: | τ
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Definition: | time τ in the expression $F(t)=A+B{\mathrm{e}}^{-t/\tau}$ of a quantity F growing or decaying exponentially towards a constant value A with increasing time t, or in the expression $F(t)=A+f(t){\mathrm{e}}^{-t/\tau}$ of an exponentially damped oscillation, where f is a periodic function of timeNote 1 to entry: The time constant of an exponentially varying quantity is the duration of a time interval at the end of which the absolute value of the difference between the quantity and the limit has decreased to 1/e of the absolute value of this difference at the beginning of the time interval, where e is the base of natural logarithms. Note 2 to entry: The time constant of a damped oscillation is the inverse of the damping coefficient. | ||

Publication date: | 2009-12 | ||

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Internal notes: | 2017-02-20: Editorial revisions in accordance with the information provided in C00020 (IEV 103) - evaluation. JGO | ||

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Note 1 to entry: The time constant of an exponentially varying quantity is the duration of a time interval at the end of which the absolute value of the difference between the quantity and the limit has decreased to 1/e of the absolute value of this difference at the beginning of the time interval, where e is the base of natural logarithms.

Note 2 to entry: The time constant of a damped oscillation is the inverse of the damping coefficient.