Circuit Theorems in AC Analysis — Engineering Board Exam Practice Questions

25 free engineering board exam reviewer questions on Circuit Theorems in AC Analysis (AC Circuits), each with the correct answer and a worked solution.

  1. Superposition is applied to an ac circuit that has two sources of different frequencies. The correct procedure is to
  2. A source has a Thevenin impedance of 30+j40, . The load is a variable pure resistance. What value of load resistance receives the maximum…
  3. The AC bridge shown is balanced (zero detector current) with Z1=100, , Z2=300, , and Z3=90-j60, . Find the unknown impedance Z4 in…
  4. In the circuit shown, V1=60 V 0° and V2=80 V 30° (the + marks are at the top), with Z1=30+j40, , Z2=50+j40, , and Z3=50-j20, . Using nodal…
  5. In the circuit shown, V1=120 V 0° and V2=100 V -45° (the + marks are at the top), with Z1=20-j50, , Z2=50-j60, , and Z3=60-j50, . Using…
  6. In the circuit shown, V1=100 V 0° and V2=80 V -60° (the + marks are at the top), with Z1=40+j50, , Z2=30-j10, , and Z3=80+j10, . Using…
  7. What is the equivalent impedance of an inductive reactance of j10, in parallel with a capacitive reactance of -j40, , in rectangular form?
  8. A network has a Thevenin voltage of 120 V (rms) and a Thevenin impedance of 30+j40, . What is the maximum average power it can deliver to…
  9. Find the equivalent impedance of (30+j40), in parallel with 60, , in polar form.
  10. A 100 0° V source has a series impedance of 3+j4, . Find the Norton equivalent current in polar form.
  11. The three equal impedances of the delta network shown are each Z =30+j60, . Find the impedance of each branch of the equivalent wye (Y)…
  12. In the circuit shown, a 240 V 0° source feeds a series branch of R1=50, and XL=60, , followed by R2=30, in parallel with a capacitor of…
  13. In the circuit shown, a 60 V 0° source feeds a series branch of R1=20, and XL=50, , followed by R2=30, in parallel with a capacitor of…
  14. A current source of 12 A 0° feeds two parallel branches, ZA=40, and ZB=60-j30, . Find the current in ZA in polar form.
  15. A 50 V 0° source drives a 20, resistor in series with an inductor of reactance j30, . The output is taken across the inductor. Find Vout…
  16. A source of 60 V 0° drives a branch Z1=60-j10, in series with the parallel branch Z2=10-j60, , as shown. A load ZL=30-j30, is connected…
  17. A source of 60 V 0° drives a branch Z1=20-j60, in series with the parallel branch Z2=-j50, , as shown. Terminals a and b are the open…
  18. A source of 240 V 0° drives a branch Z1=20-j10, in series with the parallel branch Z2=80+j50, , as shown. Terminals a and b are the open…
  19. A source of 150 V 0° drives a branch Z1=40-j50, in series with the parallel branch Z2=50+j60, , as shown. Terminals a and b are the open…
  20. A source of 100 V 0° drives a branch Z1=60, in series with the parallel branch Z2=10+j40, , as shown. Terminals a and b are the open…
  21. A source of 60 V 0° drives a branch Z1=50-j10, in series with the parallel branch Z2=60-j10, , as shown. Terminals a and b are the open…
  22. A Norton equivalent circuit for an ac source consists of
  23. The complex impedance of an ideal capacitor with capacitive reactance XC is
  24. A source has an internal impedance of Zs=40+j30, . For maximum average power transfer, the load impedance must be
  25. When finding the Thevenin impedance of an ac circuit, the independent voltage sources are replaced by