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A transformer operating at primary voltage 8 kV and secondary voltage 160 V serves a load of 80 kW at unity power factor (ideal, purely resistive). The effective loads in the primary and secondary circuits are
Asked in JEE Main 28th July 2nd Shift 2022 · Transformers
- (1) 800 Ω and 1.06 Ω
- (2) 10 Ω and 500 Ω
- (3) 800 Ω and 0.32 Ω
- (4) 1.06 Ω and 500 Ω
Answer: (3) 800 Ω and 0.32 Ω
Step-by-step solution
R=(V²)/P for each side.
Primary: ((8000)²)/(80000)=800 Ω. Secondary: (160²)/(80000)=0.32 Ω.
Why the other options are wrong
- (1) Secondary value wrong.
- (2) Both values wrong (primary and secondary swapped in size).
- (4) Primary value wrong.
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