What does a thermocouple generate to measure temperature?

What does a thermocouple generate to measure temperature?

• A. A current proportional to temperature
• B. A resistance proportional to temperature
• C. A voltage proportional to the temperature difference between the junctions of two dissimilar metals
• D. A magnetic field proportional to temperature

Answer: (C)

Thermocouples rely on the Seebeck effect: when two dissimilar metals are joined, a small voltage is produced if the two junctions are at different temperatures. That voltage is proportional to the temperature difference between the hot junction and the reference (cold) junction. In practice you measure this tiny voltage with a high-impedance instrument and, knowing the reference temperature, convert it to temperature. It’s a voltage signal, not a current, resistance change, or magnetic field, which is why this description is the correct one. Cold junction compensation is often used to account for the reference temperature so the voltage can be translated accurately into temperature.

Thermocouples rely on the Seebeck effect: when two dissimilar metals are joined, a small voltage is produced if the two junctions are at different temperatures. That voltage is proportional to the temperature difference between the hot junction and the reference (cold) junction. In practice you measure this tiny voltage with a high-impedance instrument and, knowing the reference temperature, convert it to temperature. It’s a voltage signal, not a current, resistance change, or magnetic field, which is why this description is the correct one. Cold junction compensation is often used to account for the reference temperature so the voltage can be translated accurately into temperature.