Which expression correctly describes the secondary voltage in terms of primary voltage and the transformer turns ratio?

Which expression correctly describes the secondary voltage in terms of primary voltage and the transformer turns ratio?

• A. V_secondary = V_primary × (N_primary/N_secondary)
• B. V_secondary = V_primary × (N_secondary/N_primary)
• C. V_secondary = V_primary × (N_total / N_primary)
• D. V_secondary = V_primary × (N_secondary + N_primary)

Answer: (B)

In an ideal transformer, the voltages are proportional to the turns in each winding. The basic relation is V_p / V_s = N_p / N_s, which rearranges to V_s = V_p × (N_s / N_p). This is why the secondary voltage is found by multiplying the primary voltage by the ratio of the secondary turns to the primary turns. If the secondary has more turns than the primary, the secondary voltage increases (step-up); if it has fewer turns, it decreases (step-down). Expressions that use the total turns or add the turns don’t describe the actual voltage relationship, and using the inverse ratio would give the wrong direction of change. So the correct description is V_secondary = V_primary × (N_secondary / N_primary).

In an ideal transformer, the voltages are proportional to the turns in each winding. The basic relation is V_p / V_s = N_p / N_s, which rearranges to V_s = V_p × (N_s / N_p). This is why the secondary voltage is found by multiplying the primary voltage by the ratio of the secondary turns to the primary turns.

If the secondary has more turns than the primary, the secondary voltage increases (step-up); if it has fewer turns, it decreases (step-down). Expressions that use the total turns or add the turns don’t describe the actual voltage relationship, and using the inverse ratio would give the wrong direction of change. So the correct description is V_secondary = V_primary × (N_secondary / N_primary).