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
24 V100 HzR = 40 ΩL = 150 mH

A series RL circuit is connected to a 24 V (rms), 100 Hz supply. Find the rms voltage VL across the inductor.

V = 24 V (rms)f = 100 HzR = 40 ΩL = 150 mH
VL = V
2.Easy
230 V50 HzR = 15 ΩL = 100 mHI

A series RL circuit is connected to a 230 V (rms), 50 Hz supply. Find the rms current I.

V = 230 V (rms)f = 50 HzR = 15 ΩL = 100 mH
I = A
3.Medium
120 V200 HzR = 60 ΩL = 50 mHI

A resistor and an inductor are connected in parallel across a 120 V (rms), 200 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 120 V (rms)f = 200 HzR = 60 ΩL = 50 mH
φ = °
4.Medium
10 V500 HzR = 100 ΩL = 50 mHC = 1 µF

A series RLC circuit is connected to a 10 V (rms), 500 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 10 V (rms)f = 500 HzR = 100 ΩL = 50 mHC = 1 µF
φ = °
5.Hard
VfR = 10 ΩL = 2 mHC = 1 µF

A series RLC circuit has R = 10 Ω, L = 2 mH and C = 1 µF. Find its quality factor Q at resonance.

R = 10 ΩL = 2 mHC = 1 µF
Q =
6.Hard
10 Vf0​R = 50 ΩL = 50 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 = 50 ΩL = 50 mHC = 0.22 µF
VL = V

Answer key

  1. 1. VL = 22.09 V
  2. 2. I = 6.607 A
  3. 3. φ = 43.68 °
  4. 4. φ = −58.19 °
  5. 5. Q = 4.472
  6. 6. VL = 95.35 V

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