## Circuits and Networks - Dec 2014

### 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)** Define Charge, Current, Potential difference, Lumped parameter, Time invariant, Branch and Tree.(7 marks)
**1 (b)** Calculate the node voltages for all the nodes shown in figure: 1 using nodal analysis.
(7 marks)
**2 (a)** State and explain the Maximum Power Transfer Theorem. Drive 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)** Draw the dual network shown in figure : 2.
(7 marks)
**2 (c)** Explain the dot convention rule for the magnetically coupled Network shown in figure: 3. Also formulates KVL equations.
(7 marks)

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

**3 (a)** For the circuit shown in figure: 4 find the voltages and currents for all circuit elements using mesh analysis.
(7 marks)
**3 (b)** State and explain (1) Norton's theorem (2) Milllman's theorem.(7 marks)
**3 (c)** Find current in 20 ohm resistance in the circuit shown in figure: 5 using superposition theorem.
(7 marks)
**3 (d)** State Thevenin's theorem. Calculate current passing through 60Ω resistance in the circuit shown in figure: 6, using thevenin's theorem.
(7 marks)

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

**4 (a)** In the circuit shown in figure: 7, the switch "K" is closed at t=0. Assuming no initial current through inductor. Find current at t = 0.3 sec. Also find instant of time at which voltage across R equals voltage across L.
(7 marks)
**4 (b)** Find laplace transform of f_{1}(t)=sin ωt f_{2}(t)=e^{-at} cos ωt.(7 marks)
**4 (c)** In a circuit shown in figure: 8, the switch has been at position A for a long time and is moved to position B at t = 0. Obtain current i(t) at t > 0.
(7 marks)
**4 (d)** Explain the concept of Poles and zeros and their significance.(7 marks)

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

**5 (a)** Find h-parameters of the circuit shown in figure
(7 marks)
**5 (b)** Derive expression of ABCD parameters in terms of Z and Y parameters.(7 marks)
**5 (c)** Derive relationship between incidence matrix (A), fundamental cut-set matrix (Q_{f}) and fundamental tie-set matrix (B_{f}).(7 marks)
**5 (d)** For the network shown in figure: 10 draw the oriented graph and Obtain (1) the incidence matrix (2) tieset matrix and (3) f-cutset matrix.
(7 marks)