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
120 V50 HzR = 20 ΩL = 250 mH

A series RL circuit is connected to a 120 V (rms), 50 Hz supply. Find the magnitude of the impedance |Z|.

V = 120 V (rms)f = 50 HzR = 20 ΩL = 250 mH
|Z| = Ω
2.Easy
24 V60 HzR = 30 ΩL = 250 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 = 30 ΩL = 250 mH
|Z| = Ω
3.Medium
Vf0​ = 50 HzRL = ?C = 1 µF

A series RLC circuit with C = 1 µF must resonate at 50 Hz. Find the inductance L needed.

f0 = 50 HzC = 1 µF
L = mH
4.Medium
100 V200 HzR = 20 ΩL = 150 mHC = 10 µF

A series RLC circuit is connected to a 100 V (rms), 200 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 100 V (rms)f = 200 HzR = 20 ΩL = 150 mHC = 10 µF
φ = °
5.Hard
24 V500 HzR = 15 ΩL = 100 mHC = 10 µF+−VC​

A series RLC circuit is connected to a 24 V (rms), 500 Hz supply. Find the rms voltage VC across the capacitor.

V = 24 V (rms)f = 500 HzR = 15 ΩL = 100 mHC = 10 µF
VC = V
6.Hard
5 Vf0​R = 5 ΩL = 5 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 = 5 ΩL = 5 mHC = 4.7 µF
VL = V

Answer key

  1. 1. |Z| = 81.05 Ω
  2. 2. |Z| = 98.91 Ω
  3. 3. L = 10132 mH
  4. 4. φ = 79.6 °
  5. 5. VC = 2.702 V
  6. 6. VL = 32.62 V

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