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
Vf = ?L = 5 mH

At what frequency f does a 5 mH inductor have a reactance of 150 Ω?

L = 5 mHXL = 150 Ω
f = Hz
2.Easy
24 V60 HzR = 30 ΩL = 20 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 = 30 ΩL = 20 mH
|Z| = Ω
3.Medium
24 V50 HzR = 60 ΩL = 250 mHC = 10 µFI

A series RLC circuit is connected to a 24 V (rms), 50 Hz supply. Find the power factor cos φ of the circuit.

V = 24 V (rms)f = 50 HzR = 60 ΩL = 250 mHC = 10 µF
cos φ =
4.Medium
120 V100 HzR = 40 ΩL = 20 mHC = 100 µF

A series RLC circuit is connected to a 120 V (rms), 100 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 120 V (rms)f = 100 HzR = 40 ΩL = 20 mHC = 100 µF
φ = °
5.Hard
12 V500 HzR1​ = 10 ΩR2​ = 80 ΩC = 10 µFI

A resistor R1 is connected in series with a parallel combination of R2 and a capacitor C, across a 12 V (rms), 500 Hz supply. Find the rms current I.

V = 12 V (rms)f = 500 HzR1 = 10 ΩR2 = 80 ΩC = 10 µF
I = A
6.Hard
12 V50 HzR1​ = 40 ΩR2​ = 30 ΩC = 47 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 = 40 ΩR2 = 30 ΩC = 47 µF
|Z| = Ω

Answer key

  1. 1. f = 4775 Hz
  2. 2. |Z| = 30.93 Ω
  3. 3. cos φ = 0.2428
  4. 4. φ = −4.786 °
  5. 5. I = 0.3474 A
  6. 6. |Z| = 66.02 Ω

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