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 V50 HzR = 15 ΩL = 150 mH

A series RL circuit is connected to a 120 V (rms), 50 Hz supply. Find the rms voltage VR across the resistor.

V = 120 V (rms)f = 50 HzR = 15 ΩL = 150 mH
VR = V
2.Easy
Vf = ?L = 100 mH

At what frequency f does a 100 mH inductor have a reactance of 500 Ω?

L = 100 mHXL = 500 Ω
f = Hz
3.Medium
120 V200 HzR = 30 ΩL = 100 mHC = 2.2 µF

A series RLC circuit is connected to a 120 V (rms), 200 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 120 V (rms)f = 200 HzR = 30 ΩL = 100 mHC = 2.2 µF
φ = °
4.Medium
12 V1000 HzR = 30 ΩL = 100 mHC = 1 µFI

A series RLC circuit is connected to a 12 V (rms), 1000 Hz supply. Find the rms current I.

V = 12 V (rms)f = 1000 HzR = 30 ΩL = 100 mHC = 1 µF
I = A
5.Hard
12 V50 HzR1​ = 20 ΩR2​ = 60 ΩC = 100 µF

A resistor R1 is connected in series with a parallel combination of R2 and a capacitor C, across a 12 V (rms), 50 Hz supply. Find the magnitude of the impedance |Z|.

V = 12 V (rms)f = 50 HzR1 = 20 ΩR2 = 60 ΩC = 100 µF
|Z| = Ω
6.Hard
1 Vf0​R = 20 ΩL = 20 mHC = 0.47 µF

A series RLC circuit is driven by a 1 V (rms) source whose frequency is set to the resonant frequency of the circuit. Find the rms voltage VL across the inductor.

V = 1 V (rms)R = 20 ΩL = 20 mHC = 0.47 µF
VL = V

Answer key

  1. 1. VR = 36.4 V
  2. 2. f = 795.8 Hz
  3. 3. φ = −82.76 °
  4. 4. I = 0.02553 A
  5. 5. |Z| = 41.45 Ω
  6. 6. VL = 10.31 V

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