Question

The switch in the circuit shown was on position X for a long time. The switch is then moved to position Y at time t=0. The current I(t) for t>0 is ________ (a) 0.2e^-125tu(t) mA (b) 20e^-1250tu(t) mA (c) 0.2e^-1250tu(t) mA (d) 20e^-1000tu(t) mA This question was posed to me in a job interview. This interesting question is from Dot Convention in Magnetically Coupled Circuits in section 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 (c) 0.2e^-1250tu(t) mA The best explanation: CEQ = \frac{0.8 × 0.2}{0.8+0.2} = 0.16 VC (t=0^–) = 100 V At t≥0, The discharging current I (t) = \frac{V_O}{R} e^{-\frac{t}{RC}} = \frac{100}{5000} e^{- \frac{t}{5×10^3×0.16×10^{-6}}} = 0.2e^-1250tu(t) mA.