What is the voltage ratio Vp/Vs for a transformer with Np = 90 turns and Ns = 40 turns?

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Multiple Choice

What is the voltage ratio Vp/Vs for a transformer with Np = 90 turns and Ns = 40 turns?

In an ideal transformer, the voltage ratio matches the turns ratio: Vp/Vs = Np/Ns. With Np = 90 and Ns = 40, this becomes Vp/Vs = 90/40 = 2.25. So the primary voltage is 2.25 times the secondary voltage, meaning it steps the voltage down by a factor of 2.25 (Vs = Vp/2.25). The reciprocal, Vs/Vp = 40/90 ≈ 0.444, is not what the question asks.

In an ideal transformer, the voltage ratio matches the turns ratio: Vp/Vs = Np/Ns. With Np = 90 and Ns = 40, this becomes Vp/Vs = 90/40 = 2.25. So the primary voltage is 2.25 times the secondary voltage, meaning it steps the voltage down by a factor of 2.25 (Vs = Vp/2.25). The reciprocal, Vs/Vp = 40/90 ≈ 0.444, is not what the question asks.

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