1 Answer
A thermocouple measures temperature by taking advantage of a phenomenon called the Seebeck effect. Here's a simple breakdown of how it works:
In simple terms, a thermocouple acts like a "temperature sensor" that converts temperature differences into a measurable electrical signal (voltage).
- Two Different Metals: A thermocouple is made of two wires of different metals (for example, copper and constantan) that are joined at one end. This junction is called the measurement junction.
- Temperature Difference: When the measurement junction (the part where the two metals are joined) is exposed to a temperature different from the other end (the reference junction), it generates a small voltage. This happens because the two different metals respond differently to heat.
- Voltage Generation (Seebeck Effect): The temperature difference causes the electrons in the metals to move, creating an electrical potential (voltage) at the junction. The size of this voltage depends on the temperature difference between the two junctions.
- Measuring the Voltage: The voltage produced is very small, typically in the millivolt range. This voltage is then measured by a device (like a voltmeter or a temperature controller) and is used to calculate the temperature at the measurement junction.
- Calibration: The relationship between the voltage and temperature is not linear, so thermocouples are calibrated to specific temperature ranges. For accurate measurements, the voltage is compared against known temperature standards to determine the actual temperature.
In simple terms, a thermocouple acts like a "temperature sensor" that converts temperature differences into a measurable electrical signal (voltage).