An ideal step-down transformer has 1200 turns in its primary coil and 120 turns in its secondary coil. If the primary voltage is 240 V AC, what is the secondary voltage?
Answer and explanation
Correct answer: A. 24 V AC
- Step 1: Use the ideal transformer equation: Vs / Vp = Ns / Np.
- Step 2: Substitute turns ratio: Ns / Np = 120 / 1200 = 1/10.
- Step 3: Compute secondary voltage: Vs = Vp * (1/10) = 240 / 10 = 24 V AC.
Answer
24 V AC.
Why not the others: '2400 V AC' treats the transformer as a step-up device; '12 V AC' divides by 20; '120 V AC' assumes secondary voltage equals the number of secondary turns.
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