A thermocouple consists of what?

• A. Two dissimilar metals bonded together.
• B. A single metal heated to emit electrons.
• C. A capacitor and an inductor.
• D. A battery and resistor.

Answer: (A)

A thermocouple works on the Seebeck effect, which requires two dissimilar metals bonded together to form a junction. When there is a temperature difference between the junctions, these different metals develop a small electrical voltage that can be measured to determine temperature. The key point is that the two metals must be different to produce the thermoelectric voltage.

The other descriptions don’t describe a thermocouple: heating a single metal to emit electrons is thermionic emission, not a thermoelectric effect; a capacitor and an inductor describe an LC circuit; a battery and resistor describe a power source with a load, not a temperature sensor.