Question

A moving iron ammeter produces a full-scale torque of 240 μN-m with a deflection of 120° at a current of 10 A. the rate of change of self-inductance (μH/rad) of the instrument at full scale is? (a) 2.0 μH/rad (b) 4.8 μH/rad (c) 12.0 μH/rad (d) 114.6 μH/rad This question was addressed to me in an international level competition. I would like to ask this question from Advanced Problems on Magnetically Coupled Circuits in chapter 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

The correct choice is (b) 4.8 μH/rad Explanation: At full scale position, \frac{1}{2} I^2 \frac{dL}{dθ} = TC \frac{1}{2} 10^2 \frac{dL}{dθ} = 240 × 10^-6 ∴ \frac{dL}{dθ} = 4.8 μH/rad.