AC theoryQuestion 1474 of 1506

A series circuit has a resistance of 75 Ω and an inductive reactance of 15 Ω. What is the impedance?

  1. 60.0 Ω
  2. 33.5 Ω
  3. 90.0 Ω
  4. 76.5 Ω
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Correct answer: 76.5 Ω

Z = √(R² + X²) = √(75² + 15²) = 76.5 Ω. Resistance and reactance are 90° apart, so they do not add directly.

Source: Computed, 3.3: Series Resistor-Inductor Circuits

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Questions last reviewed: 18 October 2026