The two resistors in the dashed box below, R+Ar and R-Ar, represent the sensing elements of a pressure sensor. They form one branch of a Wheatstone Bridge. In the absence of pressure (Ar = 0), the variable resistance Rx is adjusted to balance the bridge (VA - VB = 0). a) Derive expressions for V and VB as functions of the bridge resistances and Vs b) What should the value of Rx be to ensure a balanced bridge when Ar is zero? c) The output of the ideal Op Amp circuit can be written as: Vo=VAGA-VB GB. Under what condition will the Op Amp circuit behave as a true difference amplifier with gain GA = gain G? The maximum value that Ar can reach is Armax = 422. What should the value of R be in order for Vo to equal 6V at Armax? Assume that R=4k, R = Rx = 2 ks, and R3 = R = 1k d) + Vs = 12V A RA 2k Rx R+Ar B R-Ar VB R 1k www ww R3 lin Vx 41 R R ww Vo R2k +11 Low Pass Filter (for questions f & g) RF CF VOF