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 V500 HzR = 100 ΩC = 47 µF

A series RC circuit is connected to a 12 V (rms), 500 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 12 V (rms)f = 500 HzR = 100 ΩC = 47 µF
φ = °
2.Easy
10 V60 HzR = 15 ΩL = 100 mH

A series RL circuit is connected to a 10 V (rms), 60 Hz supply. Find the rms voltage VR across the resistor.

V = 10 V (rms)f = 60 HzR = 15 ΩL = 100 mH
VR = V
3.Medium
10 V200 HzR = 10 ΩL = 200 mHC = 4.7 µFI

A series RLC circuit is connected to a 10 V (rms), 200 Hz supply. Find the rms current I.

V = 10 V (rms)f = 200 HzR = 10 ΩL = 200 mHC = 4.7 µF
I = A
4.Medium
Vf0​ = 2000 HzRL = ?C = 2.2 µF

A series RLC circuit with C = 2.2 µF must resonate at 2000 Hz. Find the inductance L needed.

f0 = 2000 HzC = 2.2 µF
L = mH
5.Hard
VfR = 5 ΩL = 2 mHC = 0.047 µF

A series RLC circuit has R = 5 Ω, L = 2 mH and C = 0.047 µF. Find its quality factor Q at resonance.

R = 5 ΩL = 2 mHC = 0.047 µF
Q =
6.Hard
120 V100 HzR = 25 ΩL = 150 mHC = 22 µF+−VC​

A series RLC circuit is connected to a 120 V (rms), 100 Hz supply. Find the rms voltage VC across the capacitor.

V = 120 V (rms)f = 100 HzR = 25 ΩL = 150 mHC = 22 µF
VC = V

Answer key

  1. 1. φ = −3.874 °
  2. 2. VR = 3.697 V
  3. 3. I = 0.121 A
  4. 4. L = 2.878 mH
  5. 5. Q = 41.26
  6. 6. VC = 261.2 V

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