Red Seal Electrician Practice
AC theoryQuestion 938 of 1506

What is impedance?

  1. The total opposition to AC, as a vector sum of R and X
  2. The opposition made by the resistance of wire only
  3. The opposition from capacitance alone
  4. The ratio of power to current
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Correct answer: The total opposition to AC, as a vector sum of R and X

Impedance (Z) combines resistance and reactance as a vector sum and is measured in ohms.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 3.3: Series Resistor-Inductor Circuits

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Questions last reviewed: 18 October 2026