Q32 / 44 · NTA Abhyas (JEE Main) 2020 · Physics · Alternating Current

A series LCR circuit with 100 Ω resistance is connected to an ac source of 200 V with an angular frequency of 300 rad s-1. If only the capacitor is removed, the current lags behind the voltage by a phase of  60 ∘. If only the inductor is removed, the current leads the voltage by a phase of  60 ∘. The current and the power dissipated in the circuit is

  • A
    3 A , 300 W
  • B
    5 A ,  100 W
  • C
    4 A , 200 W
  • Correct answer
    D
    2 A , 400 W

Solution

From given condition circuit is at resonance

For LR circuit,

tan60= X L R           ⇒ X L = 3 R

For CR circuit

tan60= X C R ⇒ X C = 3 R        ⇒ X L = X C = 3 R

I rms = V rms R = 200 100 = 2 Amp

P = I 2 R = 4 × 100 = 400 Watt

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

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