ISRO Electronics & Communication (ECE) 2009 - Question 59

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Topic: Electronics Engineering

For the network shown in the figure $V_{i}(t)$ is the input and $i(t)$ is the output. The transfer function $\frac{I(s)}{V_{i}(s)}$ of the network is

  • A. $\frac{C}{RCs^{2}+LCs+1}$
  • B. $\frac{C}{LCs^{2}+RCs+1}$
  • C. $\frac{Cs}{RCs^{2}+LCs+1}$
  • D. $\frac{Cs}{LCs^{2}+RCs+1}$

Answer: D. $\frac{Cs}{LCs^{2}+RCs+1}$

Explanation: Apply KVL to the circuit:
$V_{i}(t)=Ri(t)+L\frac{di(t)}{dt}+\frac{1}{C}\int i(t)dt$
Taking Laplace transform:
$V_{i}(s)=RI(s)+LSI(s)+\frac{1}{CS}I(s)$
$\frac{I(s)}{V_{i}(s)}=\frac{1}{R+Ls+\frac{1}{Cs}} = \frac{Cs}{LCs^{2}+RCs+1}$

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