Science Buddies: "Ask an Expert"

Seebeck Effect: Turn Heat into Electricity, Then Measure It with a Thermocouple Thermometer

I'm confused with the provided data table, how would I find the Room Temperature Potential Difference (ΔVRoom) mV ? When I find ΔVTotal and the ΔVRoom, do I just simply add it together to get the Junction Potential Difference (ΔVJunc.) mV ? How do I "Adjust the range of measurement of your multimeter to the expected measurement range" for Step 3 d.? Also, the link for Step 2 under "Calibrate the Thermocouple Thermometer" the Type K thermocouple data sheet isn't working.

Please get back to me as soon as possible, thank you.

Hi Troy14,

A type K thermocouple data sheet is available here:

https://www.omega.com/techref/pdf/z204-206.pdf

The room temperature potential comes from the Type K thermocouple data sheet. Find the voltage that corresponds to the room temperature you measured on the data sheet. For example, the data sheet shows 1.000 mV at 25 deg. C.

You are correct about calculating the junction potential difference. Just add the Vtotal and the Vroom values.

As you can see from the thermocouple data sheet, junction potentials of about 4.5 mV are expected for temperatures up to 100 deg. C. So you want to set your multimeter to the millivolt (mV) range. Instructions for using your multimeter are at the following link:

https://www.sciencebuddies.org/science- ... multimeter

I hope this helps. Please ask again if you have more questions.

A. Norman

Hi A. Norman,

Do you know where I can find a reference table for a Type-T Thermocouple? Also, I've gotten a Junction Potential Difference of 3.46 mV and can't find the Junction Temperature on the Reference Sheet.

Thanks for the help.

Hi Troy14,

A type T thermocouple data sheet is available here:

https://www.omega.com/techref/pdf/z207.pdf

The type K data sheet shows that a junction voltage of 3.433 mV corresponds to 84 deg. C and a voltage of 3.474 mV corresponds with 85 deg. C. Your measurement is closer to the 3.474 mV value so I'd say your voltage represents 85 deg. C.

I hope this helps. Please ask again if you have more questions.

A. Norman