Circuits and Transmission Lines : Question Paper Dec 2011 - Electronics & Telecomm. (Semester 3)

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Circuits and Transmission Lines - Dec 2011

Electronics & Telecomm. (Semester 3)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks. 1 (a) (i) Determine current through 10Ω resistance :
(3 marks) 1 (a) (ii) Determine current through 10Ω resistance :
(2 marks) 1 (b) Find Laplace transform of signal :
(5 marks) 1 (c) Find V_C1 (f) when switch S is closed at t=0, with initial conditions :

(5 marks) 1 (d) Determine the Z parameters of the network

(5 marks) 1 (e) "Find the domain response using graphical & partial fraction method & prove that results are matching
$$ F \left(S \right)=\frac{3s}{\left(s+6 \right)\left(s+2 \right)} $$ " (5 marks) 2 (a) (i) State and explain significance of initial & find value theorems. (Network Analysis) (5 marks) 2 (a) (ii) Derive the equation for Laplace transform of following functions :
(i) Unit Ramp function
Unit impulse function (5 marks) 2 (b) Determine R_L for maximum power transfer & maximum power transferred P_L
:

(10 marks) 3 (a) (i) In case of series R-L circuit excited by DC supply (V) derive equation for transient current I_L with initial conditions. (5 marks) 3 (a) (ii) Define transmission line parameters in case of two port network. Also derive the condition of symmetry. (5 marks) 3 (b) "The driving point impedance of a one port network function is as follows. Obtain Foster 1 and Foster 2 form of equivalent circuit.
$$ Z\left(s \right)=\frac{6\left(s^2+4 \right)s}{\left(s^2+1 \right)\left(s^2+64 \right)} $$" (10 marks) 4 (a) Explain the concept of poles & zeros. Using suitable example plot pole-zero plot & hence explain how to use such plot to get time domain response for network function. (10 marks) 4 (b) "Realise given Y_LC(S) into cauer 2 form
$$ Y\left(s \right)=\frac{s^4+6s^2+4}{2s^3+4s} $$ " (10 marks) 5 (a) (i) "Check the following function for positive real function $$ (i) Z\left(s \right)=\frac{6\left(s^2+4 \right)s}{\left(s^2+1 \right)\left(s^2+64 \right)} $$
$$ \left(ii \right) Z\left(s \right)=\frac{s\left(s^2+3 \right)}{\left(s^2+1 \right)} $$ " (5 marks) 5 (a) (ii) "Check the following polynomials for Hurwitz
$$ \left(1 \right) P\left(s \right)=s^5+4s^4+3s^3+s^2+4s+1 \\ \left(2 \right) P\left(s \right)=s^4+4s^2+8 $$" (5 marks) 5 (b) (i) Obtain ABCD parameters for following two port networks. : (1)

(5 marks) 5 (b) (ii)

(5 marks) 6 (a) (i) Derive network equilibrium equation on loop current basis (KVL). (5 marks) 6 (a) (ii) For the network, get incidence matrix & tieset matrix :

(5 marks) 6 (b) "For the network determine $$ i_1, i_2, \frac{di_1}{dt}, \frac{di_2}{dt}, \frac{d^2i_1}{dt^2}, \frac{d^2i_2}{dt^2} $$
for t= 0⁺. The switch is closed at t=0. :

" (10 marks) 7 (a) (i) Determine current through 10Ω resistance for the network :

(5 marks) 7 (a) (ii) For the network, Switch S is closed at t=0 with initial conditions as shown. Determine V_R (t)

(5 marks) 7 (b) Using Superposition theorem, determine current through 10 Ω resistance. :

(10 marks)

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