Refer to Figure 19-16. Determine the Thevenin voltage for the circuit within the beige box as viewed from terminals A and B.
Refer to Figure 19-16. Determine the Thevenin voltage for the circuit within the beige box as viewed from terminals A and B.
Thevenin’s voltage for the circuit between terminals A and B is the voltage that appears across A and B with R_{L} removed from the circuit. There is no voltage drop across R_{2} because the open between terminals A and B prevents current through it. Thus, V_{AB} is the same as V_{c2} and can be found by the voltage-divider formula.
V_{AB}= V_{C2}= \left(\frac{X_{C2}\angle -90°}{R_{1}- jX_{C1}- jX_{C2}} \right)V_{s}= \left(\frac{1.5\angle -90°k\Omega }{1.0 \ k\Omega – j3 \ k\Omega } \right)10 \angle 0°V\ \ \ \ \ \ \ =\left(\frac{1.5\angle -90°k\Omega }{3.16\angle -71.6°k\Omega} \right)10\angle 0°V= 4.75\angle -18.4°V
V_{th}= V_{AB}= 4.75\angle -18.4°V