NEET 2025 · PhysicsPhase anglePrevious Year Question
To an ac power supply of 220 V at 50 Hz, a resistor of 20 Ω, a capacitor of reactance 25 Ω and an inductor of reactance 45 Ω are connected in series. The corresponding current in the circuit and the phase angle between the current and the voltage is, respectively -
- A.1.56 A and 30°
- B.1.56 A and 45°
- C.7.8 A and 30°
- D.7.8 A and 45°✓
Correct Answer
(D) 7.8 A and 45°
Solution & Explanation
Answer: (D) 7.8 A and 45° Solution: Series LCR. Net reactance X = X_L − X_C = 45 − 25 = 20 Ω. Z = √(R² + X²) = √(20² + 20²) = √800 = 20√2 Ω. I = V/Z = 220/(20√2) = 11/√2 = 7.8 A. cos φ = R/Z = 20/(20√2) = 1/√2 = cos 45° ⇒ φ = 45°.
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