[SOLVED] CS Family Name .. Given Name Student No. . Signature .

Family Name .. Given Name Student No. . Signature .
UNSW SYDNEY
School of Electrical Engineering & Telecommunications MID-SESSION EXAMINATION
Semester 1, 2017
ELEC1111
Electrical and Telecommunications Engineering
TIME ALLOWED:
TOTAL MARKS:
TOTAL NUMBER OF QUESTIONS:
60 minutes 50
5
THIS EXAM CONTRIBUTES 17.5% TO THE TOTAL COURSE ASSESSMENT
Reading Time: 5 minutes.
This paper contains 4 pages.
Candidates must ATTEMPT ALL questions.
Answer all questions in the answer booklet provided.
Marks for each question are indicated beside the question.
This paper MAY be retained by the candidate.
Print your name, student ID and question number on the front page of each answer book. Authorised examination materials:
Candidates should use their own UNSW-approved electronic calculators.
This is a closed book examination.
Assumptions made in answering the questions should be stated explicitly.
All answers must be written in ink. Except where they are expressly required, pencils may only be used for drawing, sketching or graphical work.

QUESTION 1 [7 marks]
(i) ForthecircuitinFigure1,calculatetheequivalentresistance asseenbythevoltage source terminals
4
4
8
QUESTION 2 [10 marks]
10 10 V
24 5
4
4
4 4
Figure 1.
For the circuit shown below in Figure 2:
(i) (6marks)Calculatevoltageofthethreenodes,a,bandc.
(ii) (3 marks) Calculate the power supplied/absorbed by the current source. (iii)(1 marks) Calculate the power absorbed by resistor R1.
4A
abc
5V
10 V
R1 2
2
Figure 2.
2 4
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QUESTION 3 [10 marks]
For the circuit shown below in Figure 3, use mesh analysis to write down enough equations to be able to solve for the mesh currents using the notations given in the figure. Clearly number the equations in your answers.
(Note: DO NOT SOLVE THE EQUATIONS)
15
5
10 V
Mesh1 2A 10
5
Mesh2
5
8V
Mesh 4
5V
10
Mesh 3
5
Figure 3.
QUESTION 4 [10 marks]
Find and draw the Thevenin equivalent circuit with respect to the terminals a-b. 5 mA
1 k
1 k
10 mA
a
b
1 k 5V+ 1k
1 k
1 k
Figure 4.
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QUESTION 5 [13 marks]
(i) [5marks]ForthecircuitofFigure5,calculatetheenergystoredinthecapacitorCand
the two inductors L1 andL2 when the circuit is in steady-state. 2H
10 V
+
L1
1F C L2 2H
5 5
Figure 5.
5
(ii) [8 marks] The switch of the circuit shown in Figure 6 has been in position a for a long time. At t=0, the switch moves from position a to position b. Derive an analytical expression for the voltage of the capacitor vC(t) and the current of the resistor iR(t) (i.e. as a function of time) for t > 0.
10 5a
b
t=0
1 mF
END OF PAPER
iC
+ vC
iR
10
2A
5
Figure 6.
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