Which statement is true about thermocouples and thermistors?

Which statement is true about thermocouples and thermistors?

• A. Thermocouples generate electricity; thermistors do not
• B. Thermistors generate electricity; thermocouples do not
• C. Thermistors measure room temperature
• D. Thermocouples measure humidity

Answer: (A)

Thermocouples and thermistors are both used to sense temperature, but they operate differently. A thermocouple generates an electrical signal on its own when there is a temperature difference between its two junctions, thanks to the Seebeck effect. That small voltage is what is measured by instrumentation to determine temperature. A thermistor, by contrast, is a passive device whose resistance changes with temperature; it does not produce power or voltage and must be read through a circuit that converts that resistance change into a temperature value. The other statements aren’t generally true: thermistors do not generate electricity, they measure temperature via resistance; they can measure many temperatures, not only room temperature; and humidity isn’t what a thermocouple measures—it's temperature.

Thermocouples and thermistors are both used to sense temperature, but they operate differently. A thermocouple generates an electrical signal on its own when there is a temperature difference between its two junctions, thanks to the Seebeck effect. That small voltage is what is measured by instrumentation to determine temperature. A thermistor, by contrast, is a passive device whose resistance changes with temperature; it does not produce power or voltage and must be read through a circuit that converts that resistance change into a temperature value. The other statements aren’t generally true: thermistors do not generate electricity, they measure temperature via resistance; they can measure many temperatures, not only room temperature; and humidity isn’t what a thermocouple measures—it's temperature.