Editing Temperature coefficient (section)

{{Use mdy dates|date = January 2019}}
{{Short description|Differential equation parameter in thermal physics}}
{{Use American English|date = January 2019}}

A '''temperature coefficient''' describes the relative change of a physical property that is associated with a given change in [[temperature]]. For a property ''R'' that changes when the temperature changes by ''dT'', the temperature coefficient α is defined by the following equation:
:<math>\frac{dR}{R} = \alpha\,dT</math>
Here α has the [[dimension]] of an inverse temperature and can be expressed e.g. in 1/K or K<sup>−1</sup>.

If the temperature coefficient itself does not vary too much with temperature and <math>\alpha\Delta T \ll 1</math>, a [[linear]] approximation will be useful in estimating the value ''R'' of a property at a temperature ''T'', given its value ''R''<sub>0</sub> at a reference temperature ''T''<sub>0</sub>:
:<math>R(T) = R(T_0)(1 + \alpha\Delta T),</math>
where Δ''T'' is the difference between ''T'' and ''T''<sub>0</sub>.

For strongly temperature-dependent α, this approximation is only useful for small temperature differences Δ''T''.

Temperature coefficients are specified for various applications, including electric and magnetic properties of materials as well as reactivity. The temperature coefficient of most of the reactions lies between 2 and 3.