Q74 / 90 · JEE Main 2022 (28 Jul Shift 2) · Physics

A transformer operating at primary voltage 8kV and secondary voltage 160 V serves a load of 80 kW. Assuming the transformer to be ideal with purely resistive load and working on unity power factor, the loads in the primary and secondary circuit would be

  • A
    800 Ω and 1.06 Ω
  • B
    10 Ω and 500 Ω
  • Correct answer
    C
    800 Ω and 0.32 Ω
  • D
    1.06 Ω and 500 Ω

Solution

Since the transformer is assumed to be purely resistive, the power of the transformer can be calculated with P=V2R. Therefore,

For the primary coil,

P=8×1032RP=80×103 W

⇒RP=800 Ω

For the secondary coil,

P=1602RS=80×103 W

⇒RS=0.32Ω

Hence, the correct answer is option: 'C'.

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