EEE103/24-25/S1/HW Questions
Homework Assignment (HW)
This homework assignment is comprised of five questions* from all three parts of EEE103 content, with three questions from Part 1, one question from the Part 2, and one question from Part 3. This homework assignment has a full mark of 100, which contributes to 15% of the module marks.
*Please be reminded that the Final Exam (and Resit Exam) questions in AY24/25 are comprised of three larger question (also with multiple sub-questions) - one from each part of the module content, with marks ratio of 40:30:30.
Part 1 (Weeks 1-4 content; 60 marks)
Q1. Refer to the circuit shown in Figure Q1.
(a) Use nodal analysis to calculate vx as indicated in the circuit. [12 marks]
(b) Employ superposition to determine the value of vx caused by the 5V voltage source alone. [8 marks]
Figure Q1
Q2. Consider the circuit in Figure Q2. i1, i2, i3 are the mesh currents in mesh 1, mesh 2 and mesh 3, respectively.
(a) Use mesh analysis/supermesh techniques to calculate the mesh current i1, i2, and i3. [12 marks]
(b) Calculate the power delivered or absorbed by each independent voltage source and identify which source(s) is delivering power and which source(s) is absorbing power. [8 marks]
Figure Q2
Q3. Consider the circuit in Figure Q3.
(a) Determine the Norton equivalent circuit with respect to terminal a and terminal b (i.e., drawing the Norton equivalent circuit and calculating RN and IN). [15 marks]
(b) Suppose that load resistor RL is connected between terminal a and terminal b. What’s the value of RL that will result in the maximum power transfer to the load resistor? What is the maximum power dissipation in RL. [5 marks]
Figure Q3
Part 2 (Weeks 5-8 content; 20 marks)
Q4.
(a) Calculate Vo for the circuit in Figure Q4a. [4 marks]
Figure Q4a
Figure Q4b
(b) For the single supply comparator Schmitt trigger circuit shown in Figure Q4b, to achieve a voltage output of 0 V or 5 V and a memory window between 1 V and 4 V, calculate the values of R2 and R3 ifR1 = 3 kΩ, vref = 1 V. [6 marks]
(c) For the circuit shown in Figure Q4c, determine
(i) vc (0 − ); (ii) vc (0+); (iii) The circuit time constant; (iv) vc (4 ms). [6 marks]
Figure Q4c
Figure Q4d
(d) For the circuit shown in Figure Q4d, assume an ideal op-amp, determine vo (2.5us) if vs is equal to 4e−400,000t u (t) V. [4 marks]
Part 3 (Weeks 9-12 content; 20 marks)
Q5. Figure Q5 shows an electric circuit supplied by an AC source vs(t) = 50cos(20t) V. There is a load Zload connected across the output terminals A and B. [Note: for sub-questions asking for comments, please give a concise description, and keep the number of words to below 50; for all numerical calculations, please show the correct steps in reaching the final answers.]
Figure Q5
(a) Re-draw the entire circuit in the phasor domain. Clearly state the phasor values of the voltage source, the impedances of the passive components (i.e., resistor, inductor, and capacitor), as well as the frequency at which the phasor circuit is operating. [4 marks]
(b) Given that Zload = 10 Ω (which means 10 +j0 Ω), and your task now is to solve, through phasor domain, for vload(t) and iload(t). Comment and decide on which circuit analytical method among the few below is the most convenient in your opinion to be employed for the task: mesh analysis, nodal analysis, and Thévenin equivalent circuit. Then, with the help of a clearly annotated circuit/figure, proceed to use the chosen method to solve for Vload and Iload, and then vload(t) and iload(t). [10 marks]
(c) Now, Zload, being (R +jX) Ω, is a new but unknown load. Elaborate on whether the reactance X, which only consumes reactive power, has any role in affecting the active power dissipation at Zload. Then, determine the value of Zload that would lead to maximum active power transfer/dissipation at load Zload, and compute the complex powers S absorbed by this new load. [6 marks]