Electric Circuits I: ELCT 301 Final Exam (03 January 2018)eee.guc.edu.eg/Courses/Electronics/ELCT301 Electric Circuits I/Exam… · Electric Circuits I: ELCT 301 Final Exam (03 January

Midterm Exam Electric Circuits I “ELCT 301” Time allowed: 2 hours

1

Faculty of Information Engineering & Technology (IET)

Electronics Engineering Dept.

Electric Circuits I: ELCT 301

Final Exam (03 January 2018)

Course Instructors: Prof. Dr. Eng. Tarek Abdelsalam

Prof. Dr. Eng. Yasser G. Hegazy

Instructions:

1. Answer all the questions.

2. The exam consists of 6 questions in 13 pages including this page.

3. The exam allowed time is 3 hours.

4. Electronic Calculators are allowed.

5. Clearly show all steps used in your solutions.

Please, do not write anything on this page

Total 6 5 4 3 2 1 Question

Mark

58 10 8 10 8 10 12 Out of

Bar Code

Midterm Exam Electric Circuits I “ELCT 301” Time allowed: 2 hours

2

Question # 1 [12 Marks]

The switch in the circuit shown in Figure 1 has been on position A for a long time. At t = 0 the

switch moves to position B.

a) Find the initial values of the inductor current iL(t) and the capacitor voltage V(t) at t=0

b) Find the final value of the inductor current and the capacitor voltage when the switch stays

on position B for a long time

c) Write down the mathematical expression for iL(t) for t ≥ 0.

d) Write down the mathematical expression for i(t) for t > 0

Figure 1

Midterm Exam Electric Circuits I “ELCT 301” Time allowed: 2 hours

3

Midterm Exam Electric Circuits I “ELCT 301” Time allowed: 2 hours

4

Question # 2 [10 Marks]

For the circuit shown in Figure 2:

a) Formulate the mesh current equations [ 7 Marks ]

b) Calculate the power supplied by the dependent source. [ 3 Marks ]

Figure 2

Midterm Exam Electric Circuits I “ELCT 301” Time allowed: 2 hours

5

Midterm Exam Electric Circuits I “ELCT 301” Time allowed: 2 hours

6

Question # 3 [ 8 Marks ]

a) Find the value of the resistance R in the circuit of Figure 3(a) that will result in maximum

power dissipation in the 8 resistor. [2 Marks]

Figure 3 (a)

Midterm Exam Electric Circuits I “ELCT 301” Time allowed: 2 hours

7

b) The relationship between the terminal voltage V and the current i of the linear and active

circuit is represented by the straight line where V in volts and i in Ampere as shown in

Figure 3(b). Find Thevenin equivalent circuit for the linear and active circuit [3 Marks]

Figure 3 (b)

Midterm Exam Electric Circuits I “ELCT 301” Time allowed: 2 hours

8

c) For the circuit shown in Figure 3(c), find the potential difference between the two nodes a

and b [3 Marks]

Figure 3 (c)

Midterm Exam Electric Circuits I “ELCT 301” Time allowed: 2 hours

9

Question # 4 For the circuit in Figure 4, what resistor connected across terminals a-b will absorb maximum

power from the circuit? What is that power? [ 10 Marks ]

Figure 4

Midterm Exam Electric Circuits I “ELCT 301” Time allowed: 2 hours

10

Midterm Exam Electric Circuits I “ELCT 301” Time allowed: 2 hours

11

Question # 5 [8 Marks]

For the circuit in Figure 5,

a) Obtain the equivalent capacitance. [ 2 Marks ]

b) Find the voltage across the 80 F capacitor, [ 4 Marks ]

c) Calculate the energy stored in the 20 F capacitor. [ 2 Marks ]

Figure 5

Midterm Exam Electric Circuits I “ELCT 301” Time allowed: 2 hours

12

Question # 6 [10 Marks]

For the circuit shown in Figure 6,

a) Write down the node-voltage equations [ 7 Marks ]

b) If the relationship between the output voltage V0 and the supply voltage VS is given by:

V0 = K VS. Find the value of K [ 3 Marks ]

Figure 6

Midterm Exam Electric Circuits I “ELCT 301” Time allowed: 2 hours

13