Question

The discharge of a capacitor through a ballistic galvanometer produces a damped frequency of 0.125 Hz and successive swings of 120, 96 and 76.8 mm. The logarithmic decrement is? (a) 0.225 (b) 0.565 (c) 0.484 (d) 0.7887 This question was posed to me in an interview for job. This intriguing question comes from Problems Involving Standard Time Functions topic in chapter Application of the Laplace Transform in Circuit Analysis 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

Right option is (a) 0.225 The best explanation: Logarithmic decrement, δ = ln \frac{x_1}{x_2} = ln \frac{120}{96} = 0.225 Now, δ is related to damping ratio K as, K = \frac{1}{\left(1 + (\frac{2π}{δ})^2)^{0.5}\right)} ∴ K = 0.0357.