In which unit is the output of a thermocouple most likely measured?

The output of a thermocouple is most commonly measured in millivolts. This stems from the way thermocouples work, generating a small voltage proportional to the temperature difference between their two junctions. Specifically, thermocouples create a voltage of typically a few millivolts per degree Celsius of temperature difference, making millivolts the most appropriate unit for their output measurement.

While volts might seem like a valid choice, the voltage output of most thermocouples is in the millivolt range, often measuring between a few millivolts to a few hundred millivolts depending on the temperature range and type of thermocouple used. The other units, amperes and ohms, are not suitable for measuring the voltage output of a thermocouple. Amperes measure electric current, which is not what thermocouples produce, and ohms measure resistance, which does not apply to the output voltage generated by thermocouples.