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 V100 HzR = 15 ΩL = 100 mH

A series RL circuit is connected to a 10 V (rms), 100 Hz supply. Find the rms voltage VR across the resistor.

V = 10 V (rms)f = 100 HzR = 15 ΩL = 100 mH
VR = V
2.Easy
120 V60 HzR = 20 ΩL = 150 mHI

A series RL circuit is connected to a 120 V (rms), 60 Hz supply. Find the rms current I.

V = 120 V (rms)f = 60 HzR = 20 ΩL = 150 mH
I = A
3.Medium
120 V200 HzR = 80 ΩL = 200 mHI

A resistor and an inductor are connected in parallel across a 120 V (rms), 200 Hz supply. Find the magnitude of the impedance |Z|.

V = 120 V (rms)f = 200 HzR = 80 ΩL = 200 mH
|Z| = Ω
4.Medium
100 V200 HzR = 60 ΩL = 50 mHC = 100 µFI

A series RLC circuit is connected to a 100 V (rms), 200 Hz supply. Find the power factor cos φ of the circuit.

V = 100 V (rms)f = 200 HzR = 60 ΩL = 50 mHC = 100 µF
cos φ =
5.Hard
5 Vf0​R = 2 ΩL = 10 mHC = 4.7 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 = 2 ΩL = 10 mHC = 4.7 µF
VL = V
6.Hard
12 Vf0​R = 10 ΩL = 100 mHC = 2.2 µF

A series RLC circuit is driven by a 12 V (rms) source whose frequency is set to the resonant frequency of the circuit. Find the rms voltage VL across the inductor.

V = 12 V (rms)R = 10 ΩL = 100 mHC = 2.2 µF
VL = V

Answer key

  1. 1. VR = 2.322 V
  2. 2. I = 2.001 A
  3. 3. |Z| = 76.23 Ω
  4. 4. cos φ = 0.7379
  5. 5. VL = 115.3 V
  6. 6. VL = 255.8 V

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