Red Seal Electrician Practice
Meters and troubleshootingQuestion 653 of 1506

One lamp in a parallel lamp circuit is switched off, which opens its branch. What is the effect on the other lamps?

  1. The other lamps get brighter because they share the same current.
  2. The other lamps get dimmer because the voltage falls.
  3. The other lamps turn off because the circuit is broken.
  4. Nothing. Only that branch current and the total current change.
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Correct answer: Nothing. Only that branch current and the total current change.

Every branch is across the same source voltage, so the other branch currents stay the same.

Source: Lessons in Electric Circuits I: DC (Kuphaldt), 5.7: Component Failure Analysis

Practice meters and troubleshooting

Questions last reviewed: 18 October 2026