School of Electronics, Electrical Engineering & Computer Science
ELE2024: Circuits and Control
Dr Stylianos Assimonis
Email: s.assimonis@qub.ac.uk
Coursework: Circuits
Q1. For the two-port shown in Figure 1:
1. Find the Z parameters by using the direct and indirect method.
2. Determine if the network is reciprocal.
3. Determine the equivalent T network.
4. Determine the equivalent Π network.
It is given that R1 = 10 Ω, R2 = 20 Ω, m = 5 and n = 2.
[30 marks]
−
+
V1 R2
ix −
+
V2
− +
mix
R1
−+
nV2
I1 I2
Figure 1. Circuit.
Q2. Find the voltage VL in the network depicted in Figure 2 using the Thévenin’s theo-
rem.
[30 marks]
1A
4vx
−+
2ix
10 Ω ix
5 Ω 10 Ω 20 Ω
−
+
vx
−
+
VL
Figure 2. Circuit.
1
Q3. Consider the two-port network depicted in Figure 3:
1. Show that the system equation for this circuit relating x(t) to y(t), can be
represented as:
Y (s)
X(s)
=
s2 + 1
s2 + 2s + 1
, where X(s) and Y (s) is the Laplace
transform of the x(t) and y(t), respectively.
2. Assuming that x(t) = cos(t), plot using MATLAB the y(t) for t from 0 sec. to
20 sec.
[25 marks]
−+x (t) 0.5 F 2H
1 Ω
+ −y (t)
Figure 3. Circuit.
Q4. Is the system depicted in Figure 4 linear? [15 marks]
−+x(t)
4 Ω 4 Ω
−+ 6V1 Ω
+
−
y(t)
Figure 4. Circuit.