Chapter 1, Problem 33P

A thermocouple is a temperature measurement device, which produces a voltage V proportional to the temperature at the junction of Iwo dissimilar metals. The voltage across a thermocouple is calibrated using the boiling point of water (100°C) and the freezing point of Zinc (420°C), as shown in Fig. P1.33.

The junction temperature T and the voltage across the thermocouple V satisfy the linear equation $T=\frac{1}{a}V+T_R$, where a is the thermocouple sensitivity in mV/°C and $T_R$ is the reference temperature in °C.

(a) Using the calibration data given in Fig. P1.33, find the equation of the line for the measured temperature 7’ as a function of the voltage V and determine the value of the sensitivity a and the reference temperature $T_R$.

(b) Sketch the graph of T as a function of V and clearly indicate both the reference temperature $T_R$ and the sensitivity a on the graph.