The bridge circuit provides the answer to both effects. The sensitivity of the bridge circuit for detecting small changes in resistance is well known. Furthermore, by using a dummy gauge as shown in Figure 5.16a, we can provide the required temperature compensation. In particular, the dummy is mounted in an insensitive orientation (Figure 5.16b), but in the same proximity as the active SG. Then, both gauges change in resistance from temperature effects, but the detector does not respond to a change in both strain gauges. Only the active SG responds to strain effects. This is called a one-arm bridge.
FIGURE 5.16 Strain gauges are used in pairs to provide temperature compensation. In some cases, such as this, only one gauge actually deforms during stress.