Figure 10: This circuit is known as a Wheatstone bridge; and when the resistors represent strain gauges, it can be used to
measure strain. Use this Figure for Problems 12 and 13.
12. (6.6 pts.) Given the Wheatstone bridge circuit in Figure 10, find the unknown voltage \(v\) in terms of the known input
voltage \(v_A\) and resistances \(R_1\) and \(R_2\).
(a) \(v = \frac{1}{2}v_A\)
(b) \(v = \frac{2R_2}{2R_1 + 2R_2}v_A\)
(c) \(v = 0\)
(d) \(v = \frac{R_2 - R_1}{R_1 + R_2}v_A\)
(e) \(v = \frac{R_2 - R_1}{2R_1 + 2R_2}v_A\)
(f) \(v = \frac{-R_1 + R_2}{R_1 + R_2}v_A\)
(g) none of the above
13. (6.6 pts.) Given the Wheatstone bridge circuit in Figure 10 and assuming \(v_A = 5\text{ V}\), \(R_1 = 1\text{ k}\Omega\) and \(R_2 = 5\text{ k}\Omega\),
select all paper breadboards that correctly represent this Wheatstone bridge circuit.
