Strain gauges are used amongst others to measure pressure. Figure 1 shows two strain gauges that are attached to a thin

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Strain Gauges Are Used Amongst Others To Measure Pressure Figure 1 Shows Two Strain Gauges That Are Attached To A Thin 1 (60.26 KiB) Viewed 53 times

Strain gauges are used amongst others to measure pressure. Figure 1 shows two strain gauges that are attached to a thin metal strip (E = 200-10° N/m²). The strain gauges are combined with two resistors with a fixed value into a complete bridge. When unloaded, each strain gauge has a resistance of 150 2. The fixed resistors also have a resistance of 150 2. The strain gauges have a gage factor of 2.50. To prevent damage to the strain gauges, the maximal current through them should be limited to 20 mA. active strain gauge (tension) Figure 1: Metal strip with two active strain gauges. The two strain gauges and the two fixed resistors are connected in a bridge circuit with a voltage supply Vr. The electrical equivalent circuit of this sensor is shown in Figure 2. R₁=Ro(1+x) R4 -OV₂0 R₂ R3=Ro(1+x) Figure 2: Bridge circuit with two strain gauges. I -V₂ 2+x (a) Show that the output voltage v, of the sensor circuit is equal to: (b) Does the sensor circuit shown in Figure 2 show a non-linear response when pressure is applied to the sensor? (Explain your answer) (c) What value should the voltage supply V, have to maximize the sensitivity of the sensor circuit shown in Figure 2 for a change in r? (d) Show that the output voltage v, of the sensor circuit shown in Figure 2 is equal to -4.7 mV when a pressure of 100-106 N/m² is applied to the metal strip and V, = 7.5 V.