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 V200 HzR = 50 ΩL = 250 mH

A series RL circuit is connected to a 12 V (rms), 200 Hz supply. Find the rms voltage VL across the inductor.

V = 12 V (rms)f = 200 HzR = 50 ΩL = 250 mH
VL = V
2.Easy
V60 HzL = 100 mH

Find the reactance XL of a 100 mH inductor at 60 Hz.

L = 100 mHf = 60 Hz
XL = Ω
3.Medium
230 V500 HzR = 30 ΩC = 10 µFI

A resistor and a capacitor are connected in parallel across a 230 V (rms), 500 Hz supply. Find the phase angle φ of the impedance, in degrees (positive when the current lags the voltage).

V = 230 V (rms)f = 500 HzR = 30 ΩC = 10 µF
φ = °
4.Medium
Vf0​ = 500 HzRL = 50 mHC = ?

A series RLC circuit with L = 50 mH must resonate at 500 Hz. Find the capacitance C needed.

f0 = 500 HzL = 50 mH
C = µF
5.Hard
5 Vf0​R = 50 ΩL = 20 mHC = 1 µF

A series RLC circuit is driven by a 5 V (rms) source whose frequency is set to the resonant frequency of the circuit. Find the rms voltage VL across the inductor.

V = 5 V (rms)R = 50 ΩL = 20 mHC = 1 µF
VL = V
6.Hard
100 V50 HzR = 80 ΩL = 100 mHC = 10 µFI

A series RLC circuit is connected to a 100 V (rms), 50 Hz supply. Find the rms current I.

V = 100 V (rms)f = 50 HzR = 80 ΩL = 100 mHC = 10 µF
I = A

Answer key

  1. 1. VL = 11.85 V
  2. 2. XL = 37.7 Ω
  3. 3. φ = −43.3 °
  4. 4. C = 2.026 µF
  5. 5. VL = 14.14 V
  6. 6. I = 0.3358 A

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