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Concepts Of Physics MCQ Edition [Volume 2]PhysicsAlternating Current

For a series LCR circuit connected to an AC source, the parameters are R = 300 , C = 20 F , L = 1.0 henry , E _ rms = 50 V , and = 50/ Hz . Determine the average electric field energy stored in the capacitor and the average magnetic field energy stored in the coil.

Options

  1. A50 mJ and 10 mJ
  2. B25 mJ and 5 mJ
  3. C12.5 mJ and 2.5 mJ
  4. D5 mJ and 25 mJ

Correct answer

B. 25 mJ and 5 mJ

Step-by-step solution

The angular frequency of the AC source is given by: = 2 = 2 50 = 100 rad/s The inductive reactance X_L is: X_L = L = 100 1.0 = 100 The capacitive reactance X_C is: X_C = 1 C = 1 100 20 10⁻⁶ = 500 The impedance Z of the series LCR circuit is: Z = R^2 + (X_C - X_L)^2 = 300^2 + (500 - 100)^2 = 300^2 + 400^2 = 500 The RMS current in the circuit is: I_ rms = E _ rms Z = 50 500 = 0.1 A The RMS voltage across the capacitor is: V_ C, rms = I_ rms X_C = 0.1 500 = 50 V The average electric field energy stored in the capacito

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