AC impedance & phasors worksheet with answers

Free printable AC impedance & phasors worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
24 V100 HzR = 50 ΩL = 150 mH

A series RL circuit is connected to a 24 V (rms), 100 Hz supply. Find the rms voltage VL across the inductor.

V = 24 V (rms)f = 100 HzR = 50 ΩL = 150 mH
VL = V
2.Easy
24 V50 HzR = 40 ΩL = 250 mH

A series RL circuit is connected to a 24 V (rms), 50 Hz supply. Find the magnitude of the impedance |Z|.

V = 24 V (rms)f = 50 HzR = 40 ΩL = 250 mH
|Z| = Ω
3.Medium
50 V60 HzR = 60 ΩL = 250 mHC = 10 µFI

A series RLC circuit is connected to a 50 V (rms), 60 Hz supply. Find the power factor cos φ of the circuit.

V = 50 V (rms)f = 60 HzR = 60 ΩL = 250 mHC = 10 µF
cos φ =
4.Medium
50 V60 HzR = 15 ΩL = 20 mHI

A resistor and an inductor are connected in parallel across a 50 V (rms), 60 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 50 V (rms)f = 60 HzR = 15 ΩL = 20 mH
φ = °
5.Hard
100 V500 HzR = 30 ΩL = 100 mHC = 2.2 µFI

A series RLC circuit is connected to a 100 V (rms), 500 Hz supply. Find the rms current I.

V = 100 V (rms)f = 500 HzR = 30 ΩL = 100 mHC = 2.2 µF
I = A
6.Hard
VfR = 5 ΩL = 5 mHC = 10 µF

A series RLC circuit has R = 5 Ω, L = 5 mH and C = 10 µF. Find its quality factor Q at resonance.

R = 5 ΩL = 5 mHC = 10 µF
Q =

Answer key

  1. 1. VL = 21.2 V
  2. 2. |Z| = 88.14 Ω
  3. 3. cos φ = 0.3311
  4. 4. φ = 63.31 °
  5. 5. I = 0.581 A
  6. 6. Q = 4.472

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