TransformersQuestion 1435 of 1506

A transformer must change 240 V to 120 V. The primary winding has 800 turns. How many turns must the secondary winding have?

  1. 800 turns
  2. 1200 turns
  3. 400 turns
  4. 1600 turns
Show answer

Correct answer: 400 turns

Ns = Np × (Vs ÷ Vp) = 800 × (120 ÷ 240) = 400 turns.

Source: Computed, 1.1: What is Alternating Current (AC)?

Practice transformers

Questions last reviewed: 18 October 2026