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MHT CET · Physics · Alternating Current

An a.c. source is applied to a series LR circuit with \(X_L=3 R\) and power factor is \(X_1\). Now a capacitor with \(X_C=R\) is added in series to LR circuit and the power factor is \(X_2\). The ratio \(X_1\) to \(X_2\) is

  1. A \(1: 2\)
  2. B \(2: 1\)
  3. C \(1: \sqrt{2}\)
  4. D \(\sqrt{2}: 1\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(1: \sqrt{2}\)

Step-by-step Solution

Detailed explanation

\(X_1 = \frac{R}{\sqrt{R^2 + X_L^2}} = \frac{R}{\sqrt{R^2 + (3R)^2}} = \frac{R}{\sqrt{10R^2}} = \frac{1}{\sqrt{10}}\) \(X_2 = \frac{R}{\sqrt{R^2 + (X_L - X_C)^2}} = \frac{R}{\sqrt{R^2 + (3R - R)^2}} = \frac{R}{\sqrt{R^2 + (2R)^2}} = \frac{R}{\sqrt{5R^2}} = \frac{1}{\sqrt{5}}\)
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