We were asked to calibrate a J type thermocouple.
In order to do that our reference junction was kept at 1°C while in the other junction the temperatures were raised from 22°C to 93°C (we registered the voltage every 2°C)
then we plotted the data in a graph
with the voltage in the Y axis and the ΔT in the X axis
A secondary task was to calculate the Seebeeck coefficient.
is clear to us that we need do do a regression of some kind; in HEAT and THERMODYNAMICS by Mark W. Zemansky a cubic polynomial is mention to be used, however a cuadratic equation for a restricted range of temperature is also mencioned.
The Attempt at a Solution
Our main problem is how to interpretate the data, we already did the polynomial regression as well as the cuadratic regression, but we don't know what the constants mean and how this help us to calibrate the thermocouple and calculate the seebeck coefficient.
Also we don't know what regression is the best, since the range of temperature for a cuadratic regression wasn't specified.
Rather than a full answer we are looking for references that would help us to understand what we are missing (a hint would be more than welcome though)