Answer Happy

each of these devices, what percentage of the gauge factor is due to the term depending on the change in resistivity with strain? Table 1 - Strain Gauge Parameters. Device Sensitivity / Poisson's Ratio Nominal Resistance (Ro) Gauge Factor (v) (G) Constantan 2.1 0.310 120 Ω Platinum 6.1 0.385 100 Ω (d) For both devices in Table 1 calculate the change in the resistance expected when the silo contains the grain, and feels the strain in Q2(a). Comment on the size of the resistance change, how can this be measured? (e) Draw a quarter bridge configuration, labelling the location of the constantan strain gauge and the values you have chosen for the other components. How should the circuit be setup for initial use? What is the expected output voltage when the grain is in the silo? Chose a suitable supply voltage and explain your choice. (f) In the derivation for the output voltage, we make some assumptions about the circuit and the conditions. This means that the final expression arrived at is an approximation to the actual output voltage from the bridge. Explain why it is acceptable to use this approximate equation. When will this equation no longer be accurate and how likely is this situation is to occur. [4] [5] [8] [4]