AC theoryQuestion 1485 of 1506

A series circuit has a resistance of 15 Ω and a capacitive reactance of 20 Ω. What is the impedance?

  1. 5.00 Ω
  2. 35.0 Ω
  3. 25.0 Ω
  4. 17.3 Ω
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Correct answer: 25.0 Ω

Z = √(R² + X²) = √(15² + 20²) = 25.0 Ω. Resistance and reactance are 90° apart, so they do not add directly.

Source: Computed, 4.3: Series Resistor-Capacitor Circuits

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Questions last reviewed: 18 October 2026