Two electrical strain gauges are bonded to a Duralumin cantilever and connected into a bridge circuit as shown in the figure. Each gauge has a resistance of 100 Ω and a gauge factor of 2.1. The input voltage is 4 V. The stress is 200 MN/m2, calculate the change in the value of resistance R4 to restore balance. The modulus of elasticity for Duralumin is 70 GN/m2
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