Question Paper: Circuits and Transmission Lines : Question Paper Dec 2012 - Electronics & Telecomm. (Semester 3) | Mumbai University (MU)
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## Circuits and Transmission Lines - Dec 2012

### 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) For maximum power transfer find the value of ZL if
(i) ZL is impedance
(ii) ZL is pure resistance :
(5 marks)
1 (b) find initial value of, f(t)= 20-10t-e-25t
verify using initial value theorem.
(5 marks)
1 (c) In the network given below, initial value of IL =4A and VC=100. Find IC(0+):
(5 marks)
1 (d) Current I1 and I2 entering at 1 and port 2 respectively of two port network are given by following equation.
I1 =0.5V1 - 0.2V2
I2 = -0.2V1 +V2
Obtain T and Π(pi) representation.
(5 marks)

### Attempt any FOUR from the following

1 (e) For network shown, find VC /V and draw pole-zero plot.
(5 marks)
2 (a) Using mesh analysis find power supplied by the dependent source.
(10 marks)
2 (b) Find current supplied by source.
(10 marks)
3 (a) Write B and Q matrix for the Graph shown.
(10 marks)
3 (b) Draw Bode plot for the function G(s). Find gain margin, phase margin and comment on stability.
$$G(s)= \frac{2(s+0.25)}{s^2(s+1)(s+0.5)}$$
(10 marks)
4 (a) Switch is opened at t=0 with initial conditions as shown. Find
$$v_1, \frac{dv_1}{dt}, \frac{dv_2}{dt}\ at \ time\ 0^+$$
(10 marks)
4 (b) Find Y parameter using interconnection:
(10 marks)
5 (a) In the network key is closed at t=0. Find i1 (0+), i2(0+ and i3 (0+).
(10 marks)
5 (b) Find i(t).
(10 marks)
6 (a) The circuit attain steady state with switch at position (a) & is moved to position (b) at t=0. Find V(t) for t ≥ 0.
(10 marks)
6 (b) Find Z11, Z21 and G21
(10 marks)
7 (a) Realize following functon in Foster II form

$$Z(s)=\frac{(s^2+1)(s^2+3)}{s(s^2+2)(s^2+4)}$$ (10 marks) 7 (b) Check following polynomials for Hurtwitz -
$$\ \left(i\right)\ \ p\left(s\right)=S^4+4s^2+8$$

$$\left(ii\right)\ \ p\left(s\right)=s^4+s^3+5s^2+3s+4$$(10 marks)