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NEET Physics QUESTION #1042
Question 1
To an AC supply of 220 V at 50 Hz: \(R=20\ \Omega\), capacitive reactance \(X_C=25\ \Omega\), inductive reactance \(X_L=45\ \Omega\). Current and phase angle are:
  • 15.6 A and 30°
  • 15.6 A and 45°
  • 7.8 A and 30°
  • 7.8 A and 45°✔️
Correct Answer Explanation
Impedance: \(Z=\sqrt{R^2+(X_L-X_C)^2}=\sqrt{400+(45-25)^2}=\sqrt{400+400}=\sqrt{800}=20\sqrt{2}\ \Omega\). Current \(=\frac{220}{20\sqrt{2}}=\frac{220}{28.28}\approx7.78\ \text{A}\approx7.8\ \text{A}\). Phase angle: \(\tan\phi=\frac{X_L-X_C}{R}=\frac{20}{20}=1\Rightarrow\phi=45°\).