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
10 V60 HzR = 25 ΩL = 200 mHI

A series RL circuit is connected to a 10 V (rms), 60 Hz supply. Find the rms current I.

V = 10 V (rms)f = 60 HzR = 25 ΩL = 200 mH
I = A
2.Easy
12 V50 HzR = 20 ΩL = 50 mHI

A series RL circuit is connected to a 12 V (rms), 50 Hz supply. Find the rms current I.

V = 12 V (rms)f = 50 HzR = 20 ΩL = 50 mH
I = A
3.Medium
Vf0​ = 2000 HzRL = ?C = 47 µF

A series RLC circuit with C = 47 µF must resonate at 2000 Hz. Find the inductance L needed.

f0 = 2000 HzC = 47 µF
L = mH
4.Medium
230 V200 HzR = 50 ΩC = 47 µFI

A resistor and a capacitor are connected in parallel across a 230 V (rms), 200 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 230 V (rms)f = 200 HzR = 50 ΩC = 47 µF
φ = °
5.Hard
10 Vf0​R = 20 ΩL = 5 mHC = 0.47 µF

A series RLC circuit is driven by a 10 V (rms) source whose frequency is set to the resonant frequency of the circuit. Find the rms voltage VL across the inductor.

V = 10 V (rms)R = 20 ΩL = 5 mHC = 0.47 µF
VL = V
6.Hard
120 V100 HzR1​ = 20 ΩR2​ = 30 ΩC = 47 µF

A resistor R1 is connected in series with a parallel combination of R2 and a capacitor C, across a 120 V (rms), 100 Hz supply. Find the magnitude of the impedance |Z|.

V = 120 V (rms)f = 100 HzR1 = 20 ΩR2 = 30 ΩC = 47 µF
|Z| = Ω

Answer key

  1. 1. I = 0.1259 A
  2. 2. I = 0.4719 A
  3. 3. L = 0.1347 mH
  4. 4. φ = −71.29 °
  5. 5. VL = 51.57 V
  6. 6. |Z| = 39.71 Ω

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