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 = 30 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 = 30 ΩL = 100 mH
I = A
2.Easy
12 V50 HzR = 40 ΩL = 200 mH

A series RL circuit is connected to a 12 V (rms), 50 Hz supply. Find the rms voltage VL across the inductor.

V = 12 V (rms)f = 50 HzR = 40 ΩL = 200 mH
VL = V
3.Medium
230 V200 HzR = 30 ΩL = 100 mHC = 2.2 µF

A series RLC circuit is connected to a 230 V (rms), 200 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 230 V (rms)f = 200 HzR = 30 ΩL = 100 mHC = 2.2 µF
φ = °
4.Medium
Vf0​ = 5000 HzRL = ?C = 0.22 µF

A series RLC circuit with C = 0.22 µF must resonate at 5000 Hz. Find the inductance L needed.

f0 = 5000 HzC = 0.22 µF
L = mH
5.Hard
10 Vf0​R = 15 ΩL = 100 mHC = 2.2 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 = 15 ΩL = 100 mHC = 2.2 µF
VL = V
6.Hard
100 V50 HzR = 25 ΩL = 200 mHC = 10 µF

A series RLC circuit is connected to a 100 V (rms), 50 Hz supply. Find the resonant frequency f0 of the circuit.

V = 100 V (rms)f = 50 HzR = 25 ΩL = 200 mHC = 10 µF
f0 = Hz

Answer key

  1. 1. I = 5.295 A
  2. 2. VL = 10.12 V
  3. 3. φ = −82.76 °
  4. 4. L = 4.606 mH
  5. 5. VL = 142.1 V
  6. 6. f0 = 112.5 Hz

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