Q$4$:

Two strain gauges are mounted so that they sense axial strain on a steel member in uniaxial tension. The $120$ gauges form two legs of a Wheatstone bridge and are mounted on opposite arms. For a bridge excitation voltage of $4$ V and a bridge output voltage of $120V$ under load, estimate the strain in the member. What is the resistance change experienced by each gauge? The gauge factor for each of the strain gauges is $2$ and Em for this steel is $29106$ psi.