A step-down transformer is used on a 2.2 kV line to deliver 110 V. How many turns are on the primary

JAMB Physics 2023 82 views
Source: JAMB · 2023

A step-down transformer is used on a 2.2 kV line to deliver 110 V. How many turns are on the primary windings if the secondary has 25 turns?

  1. 20
  2. 200
  3. 500 ✓
  4. 250
Explanation

For a transformer, the ratio of turns equals the ratio of voltages.

Np/Ns = Vp/Vs = 2200 ÷ 110 = 20.

Np = 20 × 25 = 500 turns. A step-down transformer always has more turns on the primary coil.

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