A coil has an inductance of 0.7 henry and is joined in series with a resistance of 220Ω. When the alternating emf of 220V at 50 Hz is applied to it then the phase through which current lags behind the

Question

A coil has an inductance of 0.7 henry and is joined in series with a resistance of 220Ω. When the alternating emf of 220V at 50 Hz is applied to it then the phase through which current lags behind the applied emf and the wattless component of current in the circuit will be respectively.

Accepted Answer

Answer: 45°, 0.5 A — XL = ωL = 2π×50×0.7 ≈ 220 tanφ = XL/R = 220/220 = 1 ⇒ φ = 45° I = V/Z = 220/√(220²+220²) = 1/√2 Wattless component = I sinφ = 1/√2 × 1/√2 = 0.5 A

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