<P> If the temperature coefficient itself does not vary too much with temperature, a linear approximation can be used to determine the value R of a property at a temperature T, given its value R at a reference temperature T: </P> <Dl> <Dd> R (T) = R (T 0) (1 + α Δ T), (\ displaystyle R (T) = R (T_ (0)) (1 + \ alpha \ Delta T),) </Dd> </Dl> <Dd> R (T) = R (T 0) (1 + α Δ T), (\ displaystyle R (T) = R (T_ (0)) (1 + \ alpha \ Delta T),) </Dd> <P> where ΔT is the difference between T and T. For strongly temperature - dependent α, this approximation is only useful for small temperature differences ΔT . </P>

The symbol for the unit of temperature coefficient of resistance is