GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER- III (New) EXAMINATION — WINTER 2019
--- Content provided by FirstRanker.com ---
Subject Code: 2130901 Date: 28/11/2019Subject Name: Circuits and Networks
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
- Attempt all questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
--- Content provided by FirstRanker.com ---
Q.1 (a) In terms of two terminal elements, define: 1) Unilateral elements, 2) Passive elements, 3) Time-variant elements. 03
(b) Draw circuit representations of ideal and practical voltage and current sources. How internal impedance affects the performance of practical voltage and current sources? 04
(c) For the network shown in figure 1, obtain the power loss in 4O and 5O resistors using mesh analysis. 07
--- Content provided by FirstRanker.com ---
Q.2 (a) Using equivalent circuit representations at t=0+, explain initial conditions in R, L and C elements. 03
(b) For the network shown in figure 1, obtain the power loss in 10O resistor using nodal analysis. 04
(c) Find out Z-parameters for the network of figure 2 07
OR
(c) Find out ABCD parameters for the network of figure 3. 07
--- Content provided by FirstRanker.com ---
Q.3 (a) State and explain substitution theorem. 03
(b) For the network shown in figure 4, switch K is closed at t=0. The current waveform is observed with CRO. The initial value of the current is measured to be 0.01 A. The transient appears to disappear in 0.1 sec. Find: 1) The value of R, 2) The value of C, 3) The equation of i(t). 04
(c) For the network given in figure 5, obtain equivalent circuit and hence find current in the branch AB using Thevenin’s theorem. 07
OR
Q.3 (a) Give various properties of positive real functions. 03
--- Content provided by FirstRanker.com ---
(b) State and explain compensation theorem. 04
(c) In the network of figure 6, capacitor C1 is charged to voltage Vo and the switch is closed at t=0. When R1=2MO, V0=1000V, R2=1MO, C1=10pF and C2=20uF, solve for d²i/dt² at t=0+. 07
Q.4 (a) Draw general nature of time response of a system when: 1) Poles are complex conjugate having negative real part. 2) Poles are imaginary with zero real part. Give your comment on the two responses. 03
(b) Explain the properties of Hurwitz polynomial. 04
(c) RL series circuit with R=25O and L=5H is connected to V=100V dc supply at time t=0. With no initial current in inductor, find: 1) Equation for circuit current i(t) 2) equations for voltage across R and L 3) Current in circuit at t=0.5sec 4) Time ‘t’ at which voltages across R and L become same. 07
--- Content provided by FirstRanker.com ---
OR
Q.4 (a) What are poles and zeroes of network functions? Explain their physical significance. 03
(b) List out steps of obtaining solution of differential equation using Laplace transformation. 04
(c) For a second order circuit, explain solution of non-homogeneous differential equations, clearly indicating all steps involved. Describe in detail, how particular integral can be evaluated using method of undetermined coefficients. 07
Q.5 (a) Describe in brief, how solution of second order homogeneous differential equations can be obtained. 03
--- Content provided by FirstRanker.com ---
(b) For the network shown in figure 7, without changing the node numbers, branch numbers and direction of branches shown in figure, obtain the reduced incidence matrix considering node 5 as the reference node. 04
(c) In the circuit of figure 8, switch is moved to position 2 after being in position 1 for a very long time. Using Laplace transformation, obtain expression for i(t) for t>0. 07
OR
Q.5 (a) Find the driving-point impedance for the network shown in figure 9. Arrange the polynomials with the highest-ordered term normalized to unity coefficient. 03
(b) Draw the oriented graph from the reduced incidence matrix of the graph given as: 04
--- Content provided by FirstRanker.com ---
A=|0 1 1 1 0
0 0 -1 -1 -1
1 0 0 0 1
(c) For the network shown in figure 7, without changing the node numbers, branch numbers and direction of branches shown in figure, obtain the tie-set and fundamental cut-set matrices considering the tree formed with branches 1, 2, 3 and 4 as the twigs of the tree. 07
Figure 3 Figure 4
--- Content provided by FirstRanker.com ---
Figure 7 Figure 8
Figure 9
--- Content provided by FirstRanker.com ---
This download link is referred from the post: GTU BE/B.Tech 2019 Winter Question Papers || Gujarat Technological University