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
100 V60 HzR = 25 ΩL = 250 mH

A series RL circuit is connected to a 100 V (rms), 60 Hz supply. Find the magnitude of the impedance |Z|.

V = 100 V (rms)f = 60 HzR = 25 ΩL = 250 mH
|Z| = Ω
2.Easy
50 V50 HzR = 40 ΩL = 100 mH

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

V = 50 V (rms)f = 50 HzR = 40 ΩL = 100 mH
VR = V
3.Medium
Vf0​ = 1000 HzRL = 200 mHC = ?

A series RLC circuit with L = 200 mH must resonate at 1000 Hz. Find the capacitance C needed.

f0 = 1000 HzL = 200 mH
C = µF
4.Medium
50 V100 HzR = 20 ΩL = 20 mHC = 22 µFI

A series RLC circuit is connected to a 50 V (rms), 100 Hz supply. Find the power factor cos φ of the circuit.

V = 50 V (rms)f = 100 HzR = 20 ΩL = 20 mHC = 22 µF
cos φ =
5.Hard
50 V100 HzR = 80 ΩL = 200 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 = 80 ΩL = 200 mHC = 4.7 µF
I = A
6.Hard
VfR = 50 ΩL = 20 mHC = 2.2 µF

A series RLC circuit has R = 50 Ω, L = 20 mH and C = 2.2 µF. Find its bandwidth B (the width of the band between the half-power frequencies), in Hz.

R = 50 ΩL = 20 mHC = 2.2 µF
B = Hz

Answer key

  1. 1. |Z| = 97.51 Ω
  2. 2. VR = 39.32 V
  3. 3. C = 0.1267 µF
  4. 4. cos φ = 0.3173
  5. 5. I = 0.2198 A
  6. 6. B = 397.9 Hz

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