Red Seal Electrician Practice
AC theoryQuestion 948 of 1506

What is the skin effect?

  1. AC tends to flow in the outer part of a conductor’s cross-section.
  2. AC flows only in the insulation.
  3. DC tends to flow only on the surface.
  4. Current is equal in all parts at any frequency.
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Correct answer: AC tends to flow in the outer part of a conductor’s cross-section.

The effect grows with frequency and cuts the effective area available for current.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 3.5: Inductor Quirks

Practice ac theory

Questions last reviewed: 18 October 2026