Which instrument is used to check the output of a thermocouple?

• A. Ammeter
• B. Ohmmeter
• C. Multimeter
• D. Voltmeter

Answer: (D)

Thermocouples produce a small voltage that varies with temperature, so you verify their output by measuring that voltage directly. A voltmeter is designed to read electrical potential difference, and it typically has high input impedance to avoid loading the fragile millivolt signal from the thermocouple. This makes the reading accurate and straightforward. An ammeter would measure current and isn’t appropriate here; an ohmmeter checks resistance; a multimeter can measure voltage but a voltmeter is the most direct, dedicated instrument for this purpose.