What is the primary difference between thermistors and thermocouples?

What is the primary difference between thermistors and thermocouples?

• A. Thermocouples generate their own electricity while thermistors do not
• B. Thermistors measure room temperate while thermocouples measure airflow
• C. Thermistors generate their own electricity and thermocouples do not
• D. Thermistors use two dissimilar metals

Answer: (A)

The main difference is how the sensor produces its signal. A thermocouple generates a small electrical voltage directly from a temperature difference between its two dissimilar metals joined at one end—the Seebeck effect. That voltage is then measured by instrumentation to infer temperature. Thermocouples are rugged, cover a wide temperature range, and give a quick electrical signal, but you often need compensation for the reference junction and the output is non-linear and small. A thermistor, by contrast, is a passive resistor whose resistance changes with temperature. It doesn’t produce voltage on its own; you apply a current or voltage and measure the resulting change in resistance to determine temperature. Thermistors offer high sensitivity and precision over a relatively narrow, well-defined temperature range and are more nonlinear, usually requiring calibration or linearization. So the correct distinction is that thermocouples generate their own signal (voltage) from temperature differences, while thermistors do not.

The main difference is how the sensor produces its signal. A thermocouple generates a small electrical voltage directly from a temperature difference between its two dissimilar metals joined at one end—the Seebeck effect. That voltage is then measured by instrumentation to infer temperature. Thermocouples are rugged, cover a wide temperature range, and give a quick electrical signal, but you often need compensation for the reference junction and the output is non-linear and small.

A thermistor, by contrast, is a passive resistor whose resistance changes with temperature. It doesn’t produce voltage on its own; you apply a current or voltage and measure the resulting change in resistance to determine temperature. Thermistors offer high sensitivity and precision over a relatively narrow, well-defined temperature range and are more nonlinear, usually requiring calibration or linearization.

So the correct distinction is that thermocouples generate their own signal (voltage) from temperature differences, while thermistors do not.