Bimetallic Thermometers
The physical phenomenon employed in a bimetallic temperature sensor is the differential thermal
expansion of two metals. Figure 8.3 shows the construction and response of a bimetallic sensor to an
input signal. The sensor is constructed by bonding two strips of different metals, A and B. The
resulting bimetallic strip may be in a variety of shapes, depending on the particular application.
Consider the simple linear construction shown in Figure 8.3. At the assembly temperature, T1, the
bimetallic strip is straight; however, for temperatures other than T1 the strip has a curvature. The
physical basis for the relationship between the radius of curvature and temperature is given as