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
120 V200 HzR = 100 ΩL = 150 mH

A series RL circuit is connected to a 120 V (rms), 200 Hz supply. Find the rms voltage VR across the resistor.

V = 120 V (rms)f = 200 HzR = 100 ΩL = 150 mH
VR = V
2.Easy
24 V60 HzR = 80 ΩL = 50 mH

A series RL circuit is connected to a 24 V (rms), 60 Hz supply. Find the magnitude of the impedance |Z|.

V = 24 V (rms)f = 60 HzR = 80 ΩL = 50 mH
|Z| = Ω
3.Medium
24 V60 HzR = 50 ΩC = 47 µFI

A resistor and a capacitor are connected in parallel across a 24 V (rms), 60 Hz supply. Find the rms current I.

V = 24 V (rms)f = 60 HzR = 50 ΩC = 47 µF
I = A
4.Medium
Vf0​ = 60 HzRL = 100 mHC = ?

A series RLC circuit with L = 100 mH must resonate at 60 Hz. Find the capacitance C needed.

f0 = 60 HzL = 100 mH
C = µF
5.Hard
12 V1000 HzR = 60 ΩL = 50 mHC = 47 µF

A series RLC circuit is connected to a 12 V (rms), 1000 Hz supply. Find the resonant frequency f0 of the circuit.

V = 12 V (rms)f = 1000 HzR = 60 ΩL = 50 mHC = 47 µF
f0 = Hz
6.Hard
VfR = 5 ΩL = 1 mHC = 1 µF

A series RLC circuit has R = 5 Ω, L = 1 mH and C = 1 µF. Find its bandwidth B (the width of the band between the half-power frequencies), in Hz.

R = 5 ΩL = 1 mHC = 1 µF
B = Hz

Answer key

  1. 1. VR = 56.24 V
  2. 2. |Z| = 82.19 Ω
  3. 3. I = 0.6413 A
  4. 4. C = 70.36 µF
  5. 5. f0 = 103.8 Hz
  6. 6. B = 795.8 Hz

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