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 = 15 ΩL = 200 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 = 15 ΩL = 200 mH
VR = V
2.Easy
24 V100 HzR = 150 ΩC = 22 µFI

A series RC circuit is connected to a 24 V (rms), 100 Hz supply. Find the rms current I.

V = 24 V (rms)f = 100 HzR = 150 ΩC = 22 µF
I = A
3.Medium
120 V500 HzR = 80 ΩL = 250 mHC = 22 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 = 80 ΩL = 250 mHC = 22 µF
cos φ =
4.Medium
24 V200 HzR = 100 ΩL = 100 mHC = 2.2 µFI

A series RLC circuit is connected to a 24 V (rms), 200 Hz supply. Find the rms current I.

V = 24 V (rms)f = 200 HzR = 100 ΩL = 100 mHC = 2.2 µF
I = A
5.Hard
VfR = 10 ΩL = 5 mHC = 0.1 µF

A series RLC circuit has R = 10 Ω, L = 5 mH and C = 0.1 µF. Find its quality factor Q at resonance.

R = 10 ΩL = 5 mHC = 0.1 µF
Q =
6.Hard
10 Vf0​R = 20 ΩL = 100 mHC = 0.22 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 = 20 ΩL = 100 mHC = 0.22 µF
VL = V

Answer key

  1. 1. VR = 1.951 V
  2. 2. I = 0.1441 A
  3. 3. cos φ = 0.1032
  4. 4. I = 0.09362 A
  5. 5. Q = 22.36
  6. 6. VL = 337.1 V

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