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
12 V60 HzR = 80 ΩL = 200 mH

A series RL circuit is connected to a 12 V (rms), 60 Hz supply. Find the rms voltage VR across the resistor.

V = 12 V (rms)f = 60 HzR = 80 ΩL = 200 mH
VR = V
2.Easy
V2000 HzC = 47 µF

Find the reactance XC of a 47 µF capacitor at 2000 Hz.

C = 47 µFf = 2000 Hz
XC = Ω
3.Medium
100 V50 HzR = 50 ΩL = 20 mHC = 4.7 µF

A series RLC circuit is connected to a 100 V (rms), 50 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 100 V (rms)f = 50 HzR = 50 ΩL = 20 mHC = 4.7 µF
φ = °
4.Medium
50 V100 HzR = 15 ΩL = 100 mHC = 4.7 µFI

A series RLC circuit is connected to a 50 V (rms), 100 Hz supply. Find the rms current I.

V = 50 V (rms)f = 100 HzR = 15 ΩL = 100 mHC = 4.7 µF
I = A
5.Hard
10 Vf0​R = 20 ΩL = 20 mHC = 10 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 = 20 mHC = 10 µF
VL = V
6.Hard
230 V100 HzR = 50 ΩL = 200 mHC = 2.2 µF

A series RLC circuit is connected to a 230 V (rms), 100 Hz supply. Find the resonant frequency f0 of the circuit.

V = 230 V (rms)f = 100 HzR = 50 ΩL = 200 mHC = 2.2 µF
f0 = Hz

Answer key

  1. 1. VR = 8.733 V
  2. 2. XC = 1.693 Ω
  3. 3. φ = −85.74 °
  4. 4. I = 0.181 A
  5. 5. VL = 22.36 V
  6. 6. f0 = 239.9 Hz

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