Red Seal Electrician Practice
Electrical mathQuestion 648 of 1506

An electrician has solved all the voltages, currents and resistances in a resistor circuit. What is one way to check the work?

  1. Check that all the resistor values add up to the supply voltage.
  2. Check that all the voltages add up to the total current.
  3. Add up the resistor powers and compare them with the total power.
  4. Repeat the same calculation again with the very same values.
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Correct answer: Add up the resistor powers and compare them with the total power.

Power is additive in any circuit, so a mismatch between the sum and the total shows a mistake.

Source: Lessons in Electric Circuits I: DC (Kuphaldt), 5.6: Correct use of Ohm’s Law

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Questions last reviewed: 18 October 2026