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An ideal transformer has a primary voltage of 8 kV and a secondary voltage of 160 V while feeding an 80 kW purely resistive load operating at unity power factor. What are the effective resistive loads seen in the primary and secondary circuits respectively?

1. (A) 800 ohm and 1.06 ohm
2. (B) 10 ohm and 500 ohm
3. (C) 800 ohm and 0.32 ohm
4. (D) 1.06 ohm and 500 ohm

Correct answer: (C) 800 ohm and 0.32 ohm

Solution

An ideal transformer conserves power, so each winding delivers/receives the same 80 kW. The equivalent resistance on a side equals V²/P using that side's voltage.

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