# Thermocouple find voltage vs. temperature

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Christie Joy Pascua on 26 Apr 2021
Edited: Christie Joy Pascua on 28 Apr 2021
x1=Array(:,1);
y1=Array(:,2);
nexttile
plot(x1,y1)
title('Voltage vs. Time of Ambient');
xlabel('Time');
ylabel('Voltage');
%Find mean
time=Array(:,1);
meanta=mean(time)
voltage=Array(:,2);
meanva=mean(voltage)
hold on
%icewater
x2=Array2(:,1);
y2=Array2(:,2);
nexttile
plot(x2,y2)
title('Voltage vs. Time of Ice Water');
xlabel('Time');
ylabel('Voltage');
hold on
%Find mean
time1=Array2(:,1);
meanti=mean(time1)
voltage1=Array2(:,2);
meanvi=mean(voltage1)

Clayton Gotberg on 26 Apr 2021
You're trying to make a calibration curve for your thermocouple, so you should know the temperature at two calibration points. Did your lab test the voltage at two known temperatures? Often, students measure the voltage of a thermocouple when it is inserted into boiling water and melting water (mixed water and ice).
If you know the voltage and temperature for two points, you can figure out how much the voltage changes when the temperature changes (the sensitivity). For example, if I read 10.5 volts when the thermocouple is in the freezing water and 0.5 volts when the thermocouple is in the hot water, I know that the voltage decreases 10 V over 100°C, meaning that the voltage changes by -0.1V/°C. Now, if I measure 5.5 V from the thermocouple, I can relate that to 50°C.
Christie Joy Pascua on 28 Apr 2021
Thank you so much for your help!