1.18 The circuit shown in Fig. P1.18 represents the equivalent circuit of an unbalanced bridge. Such equivalent circuits arise, for example, in pressure sensors where the resisances R1−4 vary with pressure and the output signal is observed across terminals 1 and 2. It is required to calculate the current in the detector branch (R5) and the voltage across it. Although this can be done by using loop and node equations, a much easier approach is possible: Find the Thévenin equivalent of the circuit to the left of node 1 and the Thévenin equivalent of the circuit to the right of node 2. Then solve the resulting simplified circuit.