Question

A 440 V, 50 HZ AC source supplies a series LCR circuit with a capacitor and a coil. If the coil has 100 mΩ resistance and 15 mH inductance, then at a resonance frequency of 50 Hz, the half power frequencies of the circuit are? (a) 50.53 Hz, 49.57 Hz (b) 52.12 HZ, 49.8 Hz (c) 55.02 Hz, 48.95 Hz (d) 50 HZ, 49 Hz This question was addressed to me in an interview. My enquiry is from Problems of Series Resonance Involving Frequency Response of Series Resonant Circuit in division Resonance & Magnetically Coupled Circuit of Network Theory Select the correct answer from above options network theory questions and answers, network theory questions pdf, network theory question bank, network theory gate questions and answers pdf, mcq on network theory pdf, gate network theory questions and solutions, network theory mcq Test , ies network theory questions, Network theory Questions for GATE EC Exam, Network Theory MCQ (Multiple Choice Questions)

Answer 1

Correct option is (a) 50.53 Hz, 49.57 Hz Explanation: Bandwidth, BW = \(\frac{f_o}{Q} = \frac{50}{47.115}\) = 1.061 Hz f2, higher half power frequency = f0 + \(\frac{BW}{2}\) ∴ f2 = 50 + \(\frac{1.061}{2}\) =50.53 Hz f1, lower half power frequency = f0 – \(\frac{BW}{2}\) ∴ f1 = 100 – \(\frac{1.59}{2}\) = 49.47 Hz.