Red Seal Electrician Practice
TransformersQuestion 1115 of 1506

An arc welder has a movable iron core. What does moving the core away from the windings do?

  1. It strengthens the coupling and raises the no-load voltage.
  2. It strengthens the coupling and lowers the no-load voltage.
  3. It weakens the coupling and lowers the no-load voltage.
  4. It weakens the coupling and raises the no-load voltage.
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Correct answer: It weakens the coupling and lowers the no-load voltage.

Less magnetic coupling between the windings gives a lower open-circuit voltage and poorer regulation, so the arc current can be adjusted.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 10.6: Voltage Regulation

Practice transformers

Questions last reviewed: 18 October 2026