The most common method of measuring and controlling temperature uses an electrical circuit called
a thermocouple. A thermocouple consists of two electrical conductors that are made of dissimilar
metals and have at least one electrical connection. This electrical connection is referred to as a
junction. A thermocouple junction may be created by welding, soldering, or by any method that
provides good electrical contact between the two conductors, such as twisting the wires around one
another. The output of a thermocouple circuit is a voltage, and there is a definite relationship
between this voltage and the temperatures of the junctions that make up the thermocouple circuit.
We will examine the causes of this voltage, and develop the basis for using thermocouples to make
engineering measurements of temperature.