Temperature dependence of resistance in Black´s equation and in calibration for SWEAT and NIST structures: the parameter TEO

The equation for resistance R(T) at temperature T can be expressed in the form R(T)=(dR/dT).(T-T_EO. When dR/dT is constant over the range of your experiment, T_EO is then a constant, the temperature at which R(T) extrapolates to zero. If we wish to express the corresponding relationship with β(T_r), the temperature coefficient of resistivity (TCR) at temperature T_r, β(T_r) is defined in the form β(T_r)=(dR/dT_r).(1/R(T_r))=1/(T _r-T_EO). For both these equations it is desirable to use the Kelvin scale for T, especially when activation energy terms occur in the test under consideration. Our experimental measurements of temperature calibration have yielded T_EO values less than 40 degrees Kelvin, and with sufficient accuracy such that materials properties can be usefully determined provided that the test temperature is not too high. When β(T_r) is specified by an independent source, it is necessary that T_r be included in both theoretical and experimental cases