JEE Main · 2022 · 28 Jul 2022 · Shift 2 · Alternating Current

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A transformer operating at primary voltage 8 kV 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) $800Ω$ and $1.06Ω$
(B) $10Ω$ and $500Ω$
(C) $800Ω$ and $0.32Ω$ ✓ Correct
(D) $1.06Ω$ and $500Ω$

Answer: (C)

Solution

For an ideal transformer with resistive load, power dissipated is

P = \frac{V ^{2}}{R}

.

For the primary circuit:

\frac{( 8 \times 1 0 ^{3} ) ^{2}}{R _{P}} = 80 \times 1 0^{3}

, giving

R_{P} = 800Ω

.

For the secondary circuit:

\frac{( 160 ) ^{2}}{R _{S}} = 80 \times 1 0^{3}

, giving

R_{S} = 0.32Ω

JEE Main · 2022 · 28 Jul 2022 · Shift 2 · Single correct option

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