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 = 40 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 = 40 ΩL = 50 mH
|Z| = Ω
2.Easy
120 V50 HzR = 80 ΩL = 200 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 = 80 ΩL = 200 mH
|Z| = Ω
3.Medium
120 V100 HzR = 20 ΩL = 50 mHC = 4.7 µF

A series RLC circuit is connected to a 120 V (rms), 100 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 120 V (rms)f = 100 HzR = 20 ΩL = 50 mHC = 4.7 µF
φ = °
4.Medium
Vf0​ = 50 HzRL = ?C = 10 µF

A series RLC circuit with C = 10 µF must resonate at 50 Hz. Find the inductance L needed.

f0 = 50 HzC = 10 µF
L = mH
5.Hard
12 V200 HzR = 50 ΩL = 50 mHC = 1 µF

A series RLC circuit is connected to a 12 V (rms), 200 Hz supply. Find the resonant frequency f0 of the circuit.

V = 12 V (rms)f = 200 HzR = 50 ΩL = 50 mHC = 1 µF
f0 = Hz
6.Hard
VfR = 2 ΩL = 20 mHC = 0.47 µF

A series RLC circuit has R = 2 Ω, L = 20 mH and C = 0.47 µF. Find its bandwidth B (the width of the band between the half-power frequencies), in Hz.

R = 2 ΩL = 20 mHC = 0.47 µF
B = Hz

Answer key

  1. 1. |Z| = 42.97 Ω
  2. 2. |Z| = 101.7 Ω
  3. 3. φ = −86.28 °
  4. 4. L = 1013 mH
  5. 5. f0 = 711.8 Hz
  6. 6. B = 15.92 Hz

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