An ideal transformer has primary input power 10 kW. The secondary current is 25 A and the primary: secondary turns ratio is 8:1. The primary voltage is:
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Question

An ideal transformer has primary input power 10 kW. The secondary current is 25 A and the primary:secondary turns ratio is 8:1. The primary voltage is:

G1 Physics · Accepted Answer

For an ideal transformer, power is conserved. The secondary voltage is Vₛ=P/Iₛ=10000/25=400 V. Since Nₚ/Nₛ=8, Vₚ/Vₛ=8, so Vₚ=8Vₛ=3200 V=10⁴×8/25 V. Hence option B.