RL Circuits — Engineering Board Exam Practice Questions

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

  1. A coil has 20 mH of inductance and 25, of series resistance. What is its quality factor Q=XL/R at 1 kHz?
  2. A coil draws 2 A from a 120 V, 60 Hz source, and the current lags the voltage by 60°. Find the inductance of the coil.
  3. A series RL circuit has R=470, and L=100 mH. At what frequency does the current lag the source voltage by 45°?
  4. In the series-parallel RL circuit shown, a 240 V (rms) source with =1000 rad/s drives R1=10, , R2=100, , and L=50 mH. Resistor R2 is in…
  5. In the series-parallel RL circuit shown, a 240 V (rms) source with =500 rad/s drives R1=25, , R2=120, , and L=400 mH. Resistor R2 is in…
  6. An inductive load takes 2000 VA at a power factor of 0.8 lagging. What is its reactive power?
  7. A series RL circuit has R=30, and XL=40, . What is its power factor?
  8. In a series RL circuit, the resistor voltage is 60 V and the inductor voltage is 80 V. What is the source voltage?
  9. A coil with 15, of resistance and 50 mH of inductance is connected across a 120 V, 60 Hz supply. Find the current.
  10. A 100, resistor and a 0.2 H inductor are connected in series across a 60 Hz source. Find the magnitude of the total impedance.
  11. In the parallel RL circuit shown, a 480 V (rms) source with =500 rad/s feeds R=30, and L=80 mH in parallel. By how many degrees does the…
  12. In the parallel RL circuit shown, a 480 V (rms) source with =1000 rad/s feeds R=96, and L=40 mH in parallel. Find the magnitude of the…
  13. In the parallel RL circuit shown, a 60 V (rms) source with =10000 rad/s feeds R=40, and L=3 mH in parallel. Find the total current drawn…
  14. In the series RL circuit shown, a 400 V (rms) source with =5000 rad/s is connected to R=28, and L=19.2 mH. Find the apparent power…
  15. In the series RL circuit shown, a 170 V (rms) source with =2000 rad/s is connected to R=150, and L=40 mH. Find the real power dissipated…
  16. In the series RL circuit shown, a 150 V (rms) source with =1000 rad/s is connected to R=24, and L=18 mH. By how many degrees does the…
  17. In the series RL circuit shown, a 232 V (rms) source with =500 rad/s is connected to R=84, and L=160 mH. Find the voltage across the…
  18. In the series RL circuit shown, a 50 V (rms) source with =1000 rad/s is connected to R=28, and L=96 mH. Find the voltage across the…
  19. In the series RL circuit shown, a 375 V (rms) source with =1000 rad/s is connected to R=240, and L=70 mH. Find the current drawn from the…
  20. Find the inductive reactance of a 2 H choke at 400 Hz.
  21. If the frequency applied to a coil is doubled, its inductive reactance
  22. What is the inductive reactance of a 50 mH inductor at 60 Hz?
  23. In a purely inductive ac circuit, the current
  24. In the parallel RL circuit shown, a 480 V (rms) source with =5000 rad/s feeds R=32, and L=4.8 mH in parallel. Find the current in the…
  25. In the series RL circuit shown, a 145 V (rms) source with =500 rad/s is connected to R=42, and L=80 mH. Find the magnitude of the total…