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 V60 HzR = 25 ΩL = 150 mH

A series RL circuit is connected to a 10 V (rms), 60 Hz supply. Find the rms voltage VR across the resistor.

V = 10 V (rms)f = 60 HzR = 25 ΩL = 150 mH
VR = V
2.Easy
100 V50 HzR = 40 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 = 40 ΩL = 50 mH
|Z| = Ω
3.Medium
230 V50 HzR = 80 ΩL = 200 mHI

A resistor and an inductor are connected in parallel across a 230 V (rms), 50 Hz supply. Find the rms current I.

V = 230 V (rms)f = 50 HzR = 80 ΩL = 200 mH
I = A
4.Medium
120 V200 HzR = 40 ΩL = 20 mHC = 22 µFI

A series RLC circuit is connected to a 120 V (rms), 200 Hz supply. Find the power factor cos φ of the circuit.

V = 120 V (rms)f = 200 HzR = 40 ΩL = 20 mHC = 22 µF
cos φ =
5.Hard
230 V60 HzR1​ = 30 ΩR2​ = 40 ΩC = 22 µF

A resistor R1 is connected in series with a parallel combination of R2 and a capacitor C, across a 230 V (rms), 60 Hz supply. Find the magnitude of the impedance |Z|.

V = 230 V (rms)f = 60 HzR1 = 30 ΩR2 = 40 ΩC = 22 µF
|Z| = Ω
6.Hard
10 Vf0​R = 50 ΩL = 20 mHC = 1 µF

A series RLC circuit is driven by a 10 V (rms) source whose frequency is set to the resonant frequency of the circuit. Find the rms voltage VL across the inductor.

V = 10 V (rms)R = 50 ΩL = 20 mHC = 1 µF
VL = V

Answer key

  1. 1. VR = 4.043 V
  2. 2. |Z| = 42.97 Ω
  3. 3. I = 4.655 A
  4. 4. cos φ = 0.964
  5. 5. |Z| = 67.11 Ω
  6. 6. VL = 28.28 V

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