Which statement best defines turns ratio?

• A. It is the ratio of the number of turns in the primary to the secondary
• B. It is the ratio of the voltages
• C. It is the product of the turns
• D. It is the difference of the voltages

Answer: (A)

The turns ratio is defined by how many turns are on the primary winding compared to the secondary winding. This ratio of turns directly sets how the transformer scales voltage: in an ideal transformer, the voltages are proportional to the turns, so Vp/Vs ≈ Np/Ns. Knowing the turns ratio lets you predict whether the transformer steps voltage up or down and by how much. The other ideas—taking a product or a difference of turns, or focusing on voltages themselves as the defining measure—don’t establish the fundamental winding relationship that the turns ratio describes.