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
10 V50 HzR = 50 ΩL = 20 mH

A series RL circuit is connected to a 10 V (rms), 50 Hz supply. Find the magnitude of the impedance |Z|.

V = 10 V (rms)f = 50 HzR = 50 ΩL = 20 mH
|Z| = Ω
2.Easy
120 V50 HzR = 100 ΩL = 20 mHI

A series RL circuit is connected to a 120 V (rms), 50 Hz supply. Find the rms current I.

V = 120 V (rms)f = 50 HzR = 100 ΩL = 20 mH
I = A
3.Medium
120 V500 HzR = 50 ΩL = 20 mHC = 100 µFI

A series RLC circuit is connected to a 120 V (rms), 500 Hz supply. Find the power factor cos φ of the circuit.

V = 120 V (rms)f = 500 HzR = 50 ΩL = 20 mHC = 100 µF
cos φ =
4.Medium
50 V50 HzR = 25 ΩL = 20 mHI

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

V = 50 V (rms)f = 50 HzR = 25 ΩL = 20 mH
φ = °
5.Hard
2 Vf0​R = 20 ΩL = 100 mHC = 0.22 µF

A series RLC circuit is driven by a 2 V (rms) source whose frequency is set to the resonant frequency of the circuit. Find the rms voltage VL across the inductor.

V = 2 V (rms)R = 20 ΩL = 100 mHC = 0.22 µF
VL = V
6.Hard
120 V200 HzR = 100 ΩL = 20 mHC = 22 µF+−VC​

A series RLC circuit is connected to a 120 V (rms), 200 Hz supply. Find the rms voltage VC across the capacitor.

V = 120 V (rms)f = 200 HzR = 100 ΩL = 20 mHC = 22 µF
VC = V

Answer key

  1. 1. |Z| = 50.39 Ω
  2. 2. I = 1.198 A
  3. 3. cos φ = 0.6424
  4. 4. φ = 75.89 °
  5. 5. VL = 67.42 V
  6. 6. VC = 43.14 V

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