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
230 V50 HzR = 20 ΩL = 200 mH

A series RL circuit is connected to a 230 V (rms), 50 Hz supply. Find the rms voltage VR across the resistor.

V = 230 V (rms)f = 50 HzR = 20 ΩL = 200 mH
VR = V
2.Easy
230 V50 HzR = 25 ΩL = 50 mH

A series RL circuit is connected to a 230 V (rms), 50 Hz supply. Find the magnitude of the impedance |Z|.

V = 230 V (rms)f = 50 HzR = 25 ΩL = 50 mH
|Z| = Ω
3.Medium
230 V100 HzR = 80 ΩL = 150 mHC = 4.7 µFI

A series RLC circuit is connected to a 230 V (rms), 100 Hz supply. Find the power factor cos φ of the circuit.

V = 230 V (rms)f = 100 HzR = 80 ΩL = 150 mHC = 4.7 µF
cos φ =
4.Medium
230 V60 HzR = 30 ΩL = 100 mHC = 4.7 µF

A series RLC circuit is connected to a 230 V (rms), 60 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 230 V (rms)f = 60 HzR = 30 ΩL = 100 mHC = 4.7 µF
φ = °
5.Hard
1 Vf0​R = 5 ΩL = 5 mHC = 2.2 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 = 5 ΩL = 5 mHC = 2.2 µF
VL = V
6.Hard
24 V500 HzR = 50 ΩL = 150 mHC = 4.7 µF

A series RLC circuit is connected to a 24 V (rms), 500 Hz supply. Find the resonant frequency f0 of the circuit.

V = 24 V (rms)f = 500 HzR = 50 ΩL = 150 mHC = 4.7 µF
f0 = Hz

Answer key

  1. 1. VR = 69.76 V
  2. 2. |Z| = 29.53 Ω
  3. 3. cos φ = 0.3111
  4. 4. φ = −86.74 °
  5. 5. VL = 9.535 V
  6. 6. f0 = 189.6 Hz

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