4th Class Power Engineering 4A9 Practice Test 2026 – Complete Exam Prep

A thermocouple generates a small voltage that is directly related to the temperature it measures. The output of a thermocouple is typically in the millivolt range, depending on the temperature differential. To accurately measure this low voltage output, an electronic instrument specifically designed for low voltage readings is required.

The millivolt meter is ideal for this purpose, as it is sensitive enough to read the small voltage levels produced by thermocouples. This instrument provides precise measurements, allowing for accurate monitoring and control of temperature in various industrial applications.

In contrast, a milliamp meter measures current, which is not applicable to the direct voltage output of a thermocouple. A watt meter measures power in watts, and while it may be used in conjunction with devices powered by thermocouples, it does not directly measure the voltage output from a thermocouple. Similarly, a milliwatt meter measures power in milliwatts and is also not suitable for directly measuring the voltage produced by a thermocouple. Thus, the millivolt meter is the correct choice for measuring the electrical output from a thermocouple.