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 = 80 ΩL = 150 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 = 80 ΩL = 150 mH
|Z| = Ω
2.Easy
24 V60 HzR = 20 ΩL = 150 mH

A series RL circuit is connected to a 24 V (rms), 60 Hz supply. Find the magnitude of the impedance |Z|.

V = 24 V (rms)f = 60 HzR = 20 ΩL = 150 mH
|Z| = Ω
3.Medium
12 V100 HzR = 80 ΩL = 200 mHC = 2.2 µFI

A series RLC circuit is connected to a 12 V (rms), 100 Hz supply. Find the power factor cos φ of the circuit.

V = 12 V (rms)f = 100 HzR = 80 ΩL = 200 mHC = 2.2 µF
cos φ =
4.Medium
Vf0​ = 50 HzRL = 200 mHC = ?

A series RLC circuit with L = 200 mH must resonate at 50 Hz. Find the capacitance C needed.

f0 = 50 HzL = 200 mH
C = µF
5.Hard
1 Vf0​R = 10 ΩL = 50 mHC = 0.22 µF

A series RLC circuit is driven by a 1 V (rms) source whose frequency is set to the resonant frequency of the circuit. Find the rms voltage VL across the inductor.

V = 1 V (rms)R = 10 ΩL = 50 mHC = 0.22 µF
VL = V
6.Hard
120 V1000 HzR = 40 ΩL = 50 mHC = 100 µFI

A series RLC circuit is connected to a 120 V (rms), 1000 Hz supply. Find the rms current I.

V = 120 V (rms)f = 1000 HzR = 40 ΩL = 50 mHC = 100 µF
I = A

Answer key

  1. 1. |Z| = 92.85 Ω
  2. 2. |Z| = 59.98 Ω
  3. 3. cos φ = 0.1326
  4. 4. C = 50.66 µF
  5. 5. VL = 47.67 V
  6. 6. I = 0.3808 A

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