If you increase the number of turns in the secondary coil, what happens to the output voltage?

• A. Increases
• B. Decreases
• C. Stays the same
• D. Fluctuates

Answer: (A)

When working with a transformer, the output voltage on the secondary side depends on how many turns it has relative to the primary. In an ideal transformer, the secondary voltage equals the primary voltage times the turns ratio: Vs = Vp × (Ns/Np). If you increase the number of turns in the secondary while keeping the primary voltage fixed, the ratio Ns/Np grows, so the secondary voltage rises proportionally. This is why adding turns on the secondary “steps up” the voltage.

Keep in mind that power tends to be preserved (ignoring losses): Is × Vs ≈ Ip × Vp, so Is typically drops as Vs increases. The other choices would only occur if the turns or input conditions were changed differently or if there were instability, but under normal conditions increasing the secondary turns increases the output voltage.