Red Seal Electrician Practice
AC theoryQuestion 506 of 1506

Why is the letter j used in front of the Y component in rectangular form?

  1. The letter j stands for joules
  2. The letter j stands for the hypotenuse
  3. The letter i is already used as the symbol for current
  4. The letter i stands for impedance
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Correct answer: The letter i is already used as the symbol for current

j avoids confusion with current.

Source: Trigonometry and Single Phase AC Generation for Electricians (Flinn), 2.3: Polar vs. Rectangular Form

Practice ac theory

Questions last reviewed: 18 October 2026