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MHT CET 2025 (19 Apr, Shift 1) · Series LCR Circuit

Series LCR Circuit question from MHT CET 2025 (19 Apr, Shift 1)

Q18MHT CET 2025 · 19 APR · SHIFT 1Medium

Series LCR Circuit

A series LCR circuit is connected to an a.c. source of 230 V, 50 Hz230\text{ V},\ 50\text{ Hz}. The circuit contains resistance of 80 Ω80\ \Omega an inductor having inductive reactance 70 Ω70\ \Omega and a capacitor of capacitive reactance 130 Ω130\ \Omega. The power factor of the circuit is xx. The value of xx is

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Answer: (b)

R = 8060Z = 100φ
  1. Power factor cos⁡ϕ=RZ\cos\phi = \dfrac{R}{Z}, with Z=R2+(XC−XL)2Z = \sqrt{R^2 + (X_C - X_L)^2}.
  2. XC−XL=130−70=60 ΩX_C - X_L = 130 - 70 = 60\ \Omega
  3. Z=802+602=100 ΩZ = \sqrt{80^2 + 60^2} = 100\ \Omega
  4. x=80100=0.8x = \dfrac{80}{100} = 0.8. So the answer is (b) 0.8.
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