Circuits and Networks - May 2015

Electronics and Comm. Engg. (Semester 3)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks. 1 (a) Explain the terms: (i) Linear (ii) Bilateral (iii) Passive (iv) Reciprocal (v) Time invariant (vi) Oriented graph and (vii) Tree.(7 marks) 1 (b) Justify: the current in an inductor and voltage across a capacitor cannot change instantaneously.(7 marks) 2 (a) State and explain maximum power transfer theorem. Also derive the condition for maximum power transfer to the load for DC and AC circuit.(7 marks)

Answer any one question from Q2 (b) & Q2 (c)

2 (b) Using mesh analysis determine mesh current i and the value of k which causes i=0 if V₁ =10 v and V₂=2 v for the network shown in figure 1. (7 marks) 2 (c) Using nodal analysis find the value of k such that V y is zero for the network shown in figure 2. (7 marks)

Answer any two question from Q3 (a), (b) & Q3 (c), (d)

3 (a) What is significance of initial condition? Write initial conditions for R, L and C at t=0 + and at t=∞.(7 marks) 3 (b) For the network shown in figure 3 the switch k is closed at t=0, also it reaches a steady state with the switch k open. Find the current i(t) for all time. (7 marks) 3 (c) What is time constant? Explain time constant in terms of RL and RC circuit.(7 marks) 3 (d) Determine V_b (0₊) and V_b (∞) for the network shown in figure 4, which reaches to steady state with switch k open and at t=0, the switch k is closed. (7 marks)

Answer any two question from Q4 (a), (b) & Q4 (c), (b)

4 (a) Explain concept of poles and zeros and their significance in network functions.(7 marks) 4 (b) Find the h parameters for the network shown in figure 5. (7 marks) 4 (c) Find Laplace transform of f₁(t)=cos ωt and f₂(t)=e^-at sin ωt.(7 marks) 4 (d) For the network shown in figure 6 determine voltage transfer gain G₁₂ =V₂/V₁. (7 marks)

Answer any two question from Q5(a), (b) & Q5 (c), (d)

5 (a) Derive relationship between incidence matrix (A), fundamental cut-set matrix (Q_f) and fundamental tie-set matrix (B_f).(7 marks) 5 (b) Find the Z parameters for the network shown in figure 7. (7 marks) 5 (c) Derive expression of h parameter in terms of Z and Y parameters.(7 marks) 5 (d) For the network shown in figure 8 draw the oriented graph. Also obtain incidence matrix (A), fundamental tie-set matrix (B_f) and fundamental cut-set matrix (Q_f). (7 marks)