RLC Circuits and Resonance — Engineering Board Exam Practice Questions

25 free engineering board exam reviewer questions on RLC Circuits and Resonance (AC Circuits), each with the correct answer and a worked solution.

  1. A 6 kW load has a power factor of 0.75 lagging. How many kvar of parallel capacitance raise the power factor to 0.95 lagging?
  2. A practical parallel resonant circuit consists of a coil (L=100, H, series resistance 10, ) in parallel with a 100 pF capacitor. Using the…
  3. The curve shows the normalized current of a series RLC circuit versus frequency. The dashed lines mark the half-power (0.707) points, at…
  4. A series RLC circuit is shown, with R=25, , L=200 mH, and C=5, F connected to a variable-frequency source of 24 V rms. What is the voltage…
  5. What capacitance must be placed in series with a 25 mH inductor so the circuit resonates at 2 kHz?
  6. In a series RLC circuit with a high Q, at resonance the voltage across the capacitor is
  7. A series RLC circuit is operated at a frequency above its resonant frequency. The circuit is
  8. A 10 kW single-phase load operates at 0.8 power factor lagging. How many kvar of capacitance must be connected in parallel to raise the…
  9. A series RLC circuit has R=30, , XL=60, , and XC=100, . What are the magnitude and nature of its impedance?
  10. A series RLC circuit has R=5, , L=20 mH, and C=0.2, F. Find its quality factor at resonance.
  11. The curve shows the normalized current of a series RLC circuit versus frequency. The dashed lines mark the half-power (0.707) points, at…
  12. A parallel RLC circuit is shown with R=100, , L=200 mH, and C=5, F, driven by a variable-frequency 120 V rms source tuned to the resonant…
  13. In the parallel RLC circuit shown, a 60 V (rms) source with =2000 rad/s is connected across R=10, , L=7.5 mH, and C=100, F in parallel…
  14. A series RLC circuit is shown, with R=8, , L=16 mH, and C=2.5, F connected to a variable-frequency source of 24 V rms. Find the quality…
  15. A series RLC circuit is shown, with R=50, , L=10 mH, and C=1, F connected to a variable-frequency source of 20 V rms. Find the resonant…
  16. In the series RLC circuit shown, a 312 V (rms) source with =2000 rad/s is connected to R=72, , L=40 mH, and C=10, F. Describe the…
  17. In the series RLC circuit shown, a 52 V (rms) source with =10000 rad/s is connected to R=12, , L=1.5 mH, and C=5, F. Find the voltage…
  18. In the series RLC circuit shown, a 29 V (rms) source with =500 rad/s is connected to R=42, , L=100 mH, and C=200, F. Find the voltage…
  19. In the series RLC circuit shown, a 17 V (rms) source with =5000 rad/s is connected to R=30, , L=12.8 mH, and C=2.5, F. Find the current in…
  20. In the series RLC circuit shown, a 15 V (rms) source with =10000 rad/s is connected to R=12, , L=3.1 mH, and C=2.5, F. Find the magnitude…
  21. A series resonant circuit has a resonant frequency of 10 kHz and a bandwidth of 500 Hz. What is its quality factor?
  22. At the resonant frequency of an ideal parallel LC circuit, the impedance seen by the source is
  23. Find the resonant frequency of a series circuit containing a 100 mH inductor and a 10, F capacitor.
  24. At series resonance, the phase angle between the source voltage and the current is
  25. At the resonant frequency of a series RLC circuit, the impedance is