Step 1: Understanding the Concept:
A thermocouple is a sensor used to measure temperature. It consists of two wires made of different metals joined together at one end (the junction).
Step 2: Key Formula or Approach:
The voltage produced is proportional to the temperature difference: $V = \alpha(T_{hot} - T_{cold})$.
Step 3: Detailed Explanation:
The Seebeck effect is a phenomenon where a temperature difference between two dissimilar electrical conductors or semiconductors produces a voltage difference between the two substances. When the junction is heated, a small DC voltage is generated that can be calibrated to provide a temperature reading.
Change in resistance is the principle for RTDs and Thermistors.
Thermal expansion is the principle for liquid-in-glass thermometers.
Step 4: Final Answer:
The thermocouple operates on the Seebeck effect.