Which sensor operates on the thermoelectric effect to generate a voltage proportional to temperature difference?

Which sensor operates on the thermoelectric effect to generate a voltage proportional to temperature difference?

• A. RTD
• B. Strain gauge
• C. Capacitive sensor
• D. Thermocouple

Answer: (D)

The thermoelectric effect, known as the Seebeck effect, is used by this sensor type to generate a voltage from a temperature difference between two dissimilar metals. A thermocouple consists of two different metals joined at one end. When the hot junction experiences a temperature that's different from the reference (cold) junction, charge carriers diffuse at different rates in the two metals, producing a small voltage at the output. That voltage is roughly proportional to the temperature difference, so by measuring it you infer the temperature difference (and, with knowledge of the reference temperature, the actual temperature). This works in contrast to the other sensors: an RTD measures how the resistance of a metal changes with temperature; a strain gauged sensor detects deformation via resistance change due to strain; and a capacitive sensor detects changes in capacitance from mechanical movement or dielectric property changes. Thermocouples uniquely rely on the generation of voltage from a temperature difference, not on resistance or capacitance.

The thermoelectric effect, known as the Seebeck effect, is used by this sensor type to generate a voltage from a temperature difference between two dissimilar metals. A thermocouple consists of two different metals joined at one end. When the hot junction experiences a temperature that's different from the reference (cold) junction, charge carriers diffuse at different rates in the two metals, producing a small voltage at the output. That voltage is roughly proportional to the temperature difference, so by measuring it you infer the temperature difference (and, with knowledge of the reference temperature, the actual temperature).

This works in contrast to the other sensors: an RTD measures how the resistance of a metal changes with temperature; a strain gauged sensor detects deformation via resistance change due to strain; and a capacitive sensor detects changes in capacitance from mechanical movement or dielectric property changes. Thermocouples uniquely rely on the generation of voltage from a temperature difference, not on resistance or capacitance.