Red Seal Electrician Practice
TransformersQuestion 1086 of 1506

A 10:1 step-down transformer (primary to secondary) delivers 20 A to its load. What is the primary current, if losses are ignored?

  1. 200 A
  2. 20 A
  3. 2 A
  4. 0.2 A
Show answer

Correct answer: 2 A

Current changes opposite to voltage. The primary current is one tenth of the secondary current: 20 A / 10 = 2 A.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 10.2: Step-up and Step-down Transformers

Practice transformers

Questions last reviewed: 18 October 2026