What is the fundamental operating principle of a thermocouple, and how does it compare to an RTD?

• A. Thermocouple generates a voltage via the Seebeck effect; RTD changes resistance with temperature; Thermocouple is rugged and inexpensive across wide ranges; RTD is more accurate and stable at moderate ranges.
• B. Thermocouple uses resistance change; RTD uses Seebeck effect.
• C. Both produce voltage from temperature difference; there is no difference.
• D. RTD generates voltage; Thermocouple changes resistance.

Answer: (A)