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JEE Main 2021 (26 Aug, Shift 2) · Parallel AC Circuits

Parallel AC Circuits question from JEE Main 2021 (26 Aug, Shift 2)

Q9JEE Main 2021 · 26 AUG · SHIFT 2Medium

Parallel AC Circuits

In the given circuit the AC source has ω\omega = 100 rad s-1. Considering the inductor and capacitor to be ideal, what will be the current I flowing through the circuit?

Figure

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Answer: (b)

VI₁ = √2 A (leads 45°)I₂ = 2√2 A (lags 45°)90° apart
  1. C branch: XC=1100×10−4=100 ΩX_C = \frac{1}{100\times10^{-4}} = 100\ \Omega, Z1=1002Z_1 = 100\sqrt{2}, I1=2I_1 = \sqrt{2} A leading VV by 45∘45^\circ.
  2. L branch: XL=100×0.5=50 ΩX_L = 100\times0.5 = 50\ \Omega, Z2=502Z_2 = 50\sqrt{2}, I2=22I_2 = 2\sqrt{2} A lagging VV by 45∘45^\circ.
  3. I1I_1 and I2I_2 are 90∘90^\circ apart: I=I12+I22=2+8=10I = \sqrt{I_1^2 + I_2^2} = \sqrt{2+8} = \sqrt{10}
  4. I≈3.16I \approx 3.16 A, so the answer is (b).
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