DipIETE – ET (NEW
SCHEME) – Code:
DE57
Subject: NETWORKS AND TRANSMISSION LINES
Time: 3 Hours Max. Marks: 100
NOTE: There are 9 Questions in all.
· Question 1 is compulsory and
carries 20 marks. Answer to Q.1 must be written in the space provided for it in
the answer book supplied and nowhere else.
· Out of the remaining EIGHT
Questions, answer any FIVE Questions. Each question carries 16 marks.
· Any required data not
explicitly given, may be suitably assumed and stated.
Q.1 Choose
the correct or the best alternative in the following: (2
10)
a. A current controlled voltage
source can be represented as:
b. Time invariant Network produces_____________.
(A) Different response at different
time.
(B) Different response at same
time.
(C) Same response at different
time.
(D) Same response at same time.
c. The period
required by the currents & voltages to adjust themselves to steady state is
termed as______________.
(A) steady state period (B) transient period
(C) varying period (D) periodic
d. Match the
element with its equivalent at t = 0 +
e. The
characterise impedance of an open wire live is___________.
(A) 
(B) 
(C) 
(D) 
f. The C value of
a constant k- high pass filter is__________.
(A) 
(B) 
(C) 
(D) 
g. The voltage
reflection coefficient is given by__________.
(A) 
(B) 
(C) 
(D) 
h. A 2-port Network is symmetrical if ___________.
(A) Z12 = Z21 (B) AD
– BC = 1
(C) A = D (D) Y11 = Y22
i.
For a distortion less line, the attenuation constant 
is given by_________.
(A) 
(B) 
(C) 
(D) 
j. Open circuit impedance Zoc of an OC line is___________.
(A) 
(B) 
(C) 
(D) 
Answer any FIVE Questions out of EIGHT
Questions.
Each question carries 16 marks.
Q.2 a. Use superposition theorem to find the voltage V in the
network shown, in Fig. 1 (4+4)
b. Write the
important features of series resonant RLC circuits? A series resonant circuit
has a capacitor of 2.5 μF and a resistor of 8Ω. Its bandwidth is 400
rad/s. Determine the value of Inductance. Also find the Quality factor. (3+5)
Q.3 a.
Write a short note on (i) Superposition Theorem (ii) Bisection Theorem. (4+4)
b. In a single current source circuit as shown in Fig. 2, find
the voltage V. Inter change the current source and the resulting voltage V, and
verity the circuit for reciprocity Theorem.
(8)
Q.4 a. Calculate the characteristics impedance, propagation constant and
line constants of an open wire loss less line 50 km long Zoc and Zsc at 700 Hz
were 286 
and 1520 
and velocity of propagation of the line is assumed to be 1.86
105 km/sec. (42)
b. The
switch K in Fig. 3 is moved from position a
to b at time t=0. Just before the switch
is thrown, initial conditions are
.Find the current i(t) after the switching actions. (8)
Q.5 a. The network consists of 2 star connected circuits in parallel as
shown in Fig 4. Obtain the simple delta connected equivalent of the network. (10)
b. Calculate the input impedance of the network as shown in Fig.5. (6)
Q.6 a. Derive the expressions
to write
(i) z parameters in terms of
A, B, C, D
(ii) y parameter in
terms of h parameters (4+4)
b. Find
the characteristics impedance & propagation constant for a Bridged
T Network. (8)
Q.7
a. For a 
- network shown in Fig. 6. Calculate the image impedance of the
network. (8)
b. Derive the
expressions for OC & SC impedances of a line of length L. (8)
Q.8 a. The
OC & SC impedance at 1 kHz of a 50 km long uniform transmission line are 
and 
respectively. Calculate the
values of
. (4+4)
b. Derive the
relationship between SWR and Reflection coefficient k. (8)
Q.9 a. Design a low pass filter with L and C
values. (8)
b. Design the elements for an asymmetrical L attenuator. (8)