Transformer Turns Ratio

Steps:

• Voltage ratio equals turns ratio: $V_p / V_s = N_p / N_s$.
• Rearrange for secondary turns: $N_s = N_p \times (V_s / V_p)$.
• Substitute values: $N_s = 600 \times (12 / 240)$.
• Simplify: $12 / 240 = 0.05$, so $600 \times 0.05 = 30$.

Why B is correct:

• Matches the transformer law where secondary turns are primary turns scaled by the voltage step-down ratio.

Why the others are wrong:

• A: Underestimates by using incorrect ratio like 600 / 30.
• C: Assumes 1:1 ratio, ignoring voltage change.
• D: Inverts ratio for step-up, yielding 600 × (240 / 12) = 12,000.

Final answer: B