What occurs when the Thermocouple Assembly is heated?

• A. It expands and causes vibrations
• B. It creates a small voltage proportional to temperature
• C. It disconnects from the circuit
• D. It changes color

Answer: (B)

When the Thermocouple Assembly is heated, it generates a small voltage that is directly proportional to the temperature difference between its two junctions. This phenomenon is based on the Seebeck effect, where a temperature gradient within the thermoelectric materials causes the motion of charge carriers, resulting in the production of a voltage signal. This voltage can then be measured and used for temperature readings.

Thermocouples are commonly used in various applications, including aircraft engines, because they provide accurate temperature measurements by converting thermal energy into electrical energy. The generated voltage can be interpreted by instruments, making thermocouples essential for monitoring and control in aviation systems.

The other choices do not accurately describe the primary function of a thermocouple when heated: expansion and vibrations relate more to physical changes, disconnection from the circuit does not generally happen solely due to heating, and color change may occur in some materials with temperature but is not a fundamental characteristic of how thermocouples operate or measure temperature.