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CUET · PHYSICS · PYQ PAPER 2023

What is the power factor of an ac circuit having resistance R and inductance L connected in series? (\( \omega \) is the angular frequency )

  1. A \( (\omega L)R^{-1} \)
  2. B \( R(\omega L)^{-1} \)
  3. C \( R(R^2 - \omega^2 L^2)^{-1/2} \)
  4. D \( R(R^2 + \omega^2 L^2)^{-1/2} \)
Verified Solution

Answer & Solution

Correct Answer

(D) \( R(R^2 + \omega^2 L^2)^{-1/2} \)

Step-by-step Solution

Detailed explanation

Impedance \( Z = \sqrt{R^2 + (\omega L)^2} \) Power factor \( \text{PF} = \frac{R}{Z} \) Power factor \( = \frac{R}{\sqrt{R^2 + (\omega L)^2}} = R(R^2 + \omega^2 L^2)^{-1/2} \)
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