Q119 / 180 · NEET 2018 · Physics

An inductor 20 mH, capacitor 100 μF and a resistor 50 Ω are connected in series across a source of emf, V= 10sin⁡(314t⁡). The power loss in the circuit is

  • A
    2.74  W
  • B
    0.43  W
  • Correct answer
    C
    0.79  W
  • D
    1.13  W

Solution

V0=10 V, ω=314  rad/s

P=VrmsIrmscos⁡ϕ

P= V rms V rms Z R Z

= ( V rms ) 2 R Z 2

XL=ωL=314 20×10-3=6.280

XC=1ωC=1314×100×10-6=31.84 Ω

R=50 Ω

Z= ( X C − X L ) 2 + R 2

=  31.84-6.282+502=56 Ω

⇒P= ( 10 2 ) 2 × 50 ( 56 ) 2 =0.79 W

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

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