The output from a thermocouple is primarily measured by what type of meter?

The output from a thermocouple is primarily measured using a millivolt meter because thermocouples generate a voltage in the millivolt range as a result of the thermoelectric effect. When two dissimilar metals are joined at two junctions and subjected to different temperatures, they produce a small voltage that corresponds to the temperature difference.

Millivolt meters are specifically designed to measure low voltages accurately, making them ideal for this application. They offer the sensitivity needed to detect the minor voltage changes produced by the thermocouple, allowing for precise temperature readings.

Other types of meters do not fit this application as effectively. Watt meters are used for measuring electrical power, milliwatt meters are meant for slightly higher power applications, and milliamp meters measure current. Thus, they are not suited for the specific requirements of measuring the small voltage output from thermocouples.