Transformer turns ratio determines voltage ratio

Steps:

• Calculate voltage ratio: input voltage / output voltage = 24 V / 6 V = 4.
• The turns ratio equals the voltage ratio: input turns / output turns = 4.
• Solve for output turns: output turns = input turns / 4 = 720 / 4 = 180.
• Thus, the output coil has 180 turns.

Why B is correct:

• By the transformer law, V_p / V_s = N_p / N_s, so N_s = N_p × (V_s / V_p) = 720 × (6/24) = 180.

Why the others are wrong:

• A: 5 turns inverts the ratio and divides incorrectly (720 × 6/24 ≠ 5).
• C: 2000 turns assumes step-up transformer, but 24 V to 6 V is step-down.
• D: 10000 turns results from erroneous multiplication (e.g., 720 × 24/6 × something extra).

Final answer: B