Power factor and three-phaseQuestion 490 of 1506

A circuit has a resistance of 30 ohms and an inductive reactance of 40 ohms. What is the impedance?

  1. 70 ohms
  2. 10 ohms
  3. 1200 ohms
  4. 50 ohms
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Correct answer: 50 ohms

Z = sqrt(30^2 + 40^2) = sqrt(2500) = 50 ohms.

Source: Trigonometry and Single Phase AC Generation for Electricians (Flinn), 1.6: Power and Impedance Triangles

Practice power factor and three-phase

Questions last reviewed: 18 October 2026