EEE103 Electrical Circuits 1 2021 22 Semester 1
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2021 22 Semester 1 - Resit (Open-Book Exam)
Bachelor Degree - Year 2
EEE103
Electrical Circuits 1
Question 1 (20 marks)
(a) In Figure 1, the same DC current flows through each element in the circuit.
i. Suppose Vt = 2 V, determine the power absorbed by the voltage-controlled current source.
ii. Given that element A absorbs 100 W from the circuit, calculate the value of Vs by applying KVL to the loop.
Vs 8 V 5Vt
+
Figure 1: Circuit for question 1(a)
(b) Calculate the voltage v as labeled in the circuit of Figure 2, and compute the power
supplied by the two current sources.
+ |
1 |
|
v 3 A 6 Ω
– |
|
|
Figure 2: Circuit for question 1(b)
Question 2 (20 marks)
Determine the voltage v1 , v2 , and v3 in the circuit shown in Figure 3. Write down the proper solution process and present relevant equations in the simplest form of Av1 + Bv2 + Cv3 = D .
Reference node
Figure 3: Circuit for question 2
(a) Apply KCL to supernode v1 -v3 and write down the relevant KCL equation. (b) Apply KCL to v2 and write down the relevant KCL equation.
(c) Derive the third equation aCrOSS the supernode.
(d) Solve equations above using substitution method and calculate v1 , v2 , and v3 .
Question 3 (20 marks)
For the circuit in Figure 4, find the Thevenin Equivalent Circuit (TEC) across RL terminals:
(a) Calculate the open-circuit voltage.
(b) Calculate RTH .
(c) What value of RL will ensure that it absorbs the maximum amount of
power?
3 Ω
O
O
Figure 4: Circuit for question 3
Question 4 (20 marks)
(a) For the circuit in Figure 5 , the switch s1 is opened at t = 0 s. Answer the following questions.
t = 0 s
L
i● Determine i t at t equal t o 0- and 0+ s.
ii● Determine an expression of iL valid for t > 0 S .
(b) Consider the network depicted in Figure 6 . An AC source of angular frequency w = 100 rad/s will be connected across the "open terminals":
ii. Determine the equivalent impedance seen looking into the open terminals.
10 mF 20 Ω
open terminals → 25 Ω 55 Ω 20 mH
Figure 6: Circuit for question 4(b)
Question 5 (20 marks)
In Figure 7, the capacitor is connected to a parallel source of 4.5 V when t = 0- , and is disconnected when t = 0 sS The time-domain representation of the voltage source vs is 2e -tu(t).
Figure 7: Circuit diagram for question 5
(a) Apply KVL to the circuit and determine the KVL equation in time-domain and s-domain.
(b) Derive I(s) and apply Inverse Laplace Transform to determine the time-domain current i(t).
2023-01-08