Engineering Board Exam Reviewer · RL Circuits · easy

If the frequency applied to a coil is doubled, its inductive reactance

  1. is halved
  2. is doubled
  3. stays the same
  4. is quadrupled

Answer

B. is doubled

Solution

XL=2π fL is directly proportional to frequency, so doubling f doubles XL.

More RL Circuits questions

  1. What is the inductive reactance of a 50 mH inductor at 60 Hz?
  2. In a purely inductive ac circuit, the current
  3. 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…
  4. 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…
  5. A coil has 20 mH of inductance and 25, of series resistance. What is its quality factor Q=XL/R at 1 kHz?
  6. 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.
  7. A series RL circuit has R=470, and L=100 mH. At what frequency does the current lag the source voltage by 45°?
  8. 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…
  9. 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…
  10. An inductive load takes 2000 VA at a power factor of 0.8 lagging. What is its reactive power?

All RL Circuits questions