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
100 V50 HzR = 30 ΩL = 50 mH

A series RL circuit is connected to a 100 V (rms), 50 Hz supply. Find the magnitude of the impedance |Z|.

V = 100 V (rms)f = 50 HzR = 30 ΩL = 50 mH
|Z| = Ω
2.Easy
V100 HzC = 47 µF

Find the reactance XC of a 47 µF capacitor at 100 Hz.

C = 47 µFf = 100 Hz
XC = Ω
3.Medium
100 V60 HzR = 100 ΩL = 200 mHC = 10 µFI

A series RLC circuit is connected to a 100 V (rms), 60 Hz supply. Find the power factor cos φ of the circuit.

V = 100 V (rms)f = 60 HzR = 100 ΩL = 200 mHC = 10 µF
cos φ =
4.Medium
230 V100 HzR = 15 ΩL = 20 mHC = 47 µF

A series RLC circuit is connected to a 230 V (rms), 100 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 230 V (rms)f = 100 HzR = 15 ΩL = 20 mHC = 47 µF
φ = °
5.Hard
12 V50 HzR = 30 ΩL = 200 mHC = 10 µFI

A series RLC circuit is connected to a 12 V (rms), 50 Hz supply. Find the rms current I.

V = 12 V (rms)f = 50 HzR = 30 ΩL = 200 mHC = 10 µF
I = A
6.Hard
5 Vf0​R = 50 ΩL = 5 mHC = 0.47 µF

A series RLC circuit is driven by a 5 V (rms) source whose frequency is set to the resonant frequency of the circuit. Find the rms voltage VL across the inductor.

V = 5 V (rms)R = 50 ΩL = 5 mHC = 0.47 µF
VL = V

Answer key

  1. 1. |Z| = 33.86 Ω
  2. 2. XC = 33.86 Ω
  3. 3. cos φ = 0.466
  4. 4. φ = −54.84 °
  5. 5. I = 0.04665 A
  6. 6. VL = 10.31 V

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