Unformatted text preview: KING FAHD UNIVERSITY OF PETROLEUM & MINERALS
Department of Electrical Engineering
Time Allowed 2 and 1/2 Hours
June 5, 2004 Instructor: Dr. Alakhdhar
Student Name :
Student ID# : Score
The problems have equal weights 1Ω
- (10pts.) 2Ω
i 3Ω 1A +
- Problem 1:
Apply superposition to calculate the current i in the circuit shown. 3vV Problem 2:
For the ideal op-amp circuit shown:
a) Find the voltage v o .
b) Calculate the power absorbed by the 4 Ω resistor. (8pts.)
(2pts.) 3Ω 1Ω 1V 2Ω
4Ω 15 V + v0
-15 V Problem 3:
For the circuit shown:
a) Find the value of the load which absorbs maximum power.
b) Find the maximum power absorbed by the load. (7pts.)
(3pts.) 20 Ω
10 cos(5000t) A 5Ω 100 µΗ Load Problem 4:
The switch in the circuit shown has been open for a long time before closing at t = 0.
a) Find the initial value iL(0+).
b) Find the final value iL(∞).
c) Find the time constant of the circuit for t ≥ 0 .
d) Find the initial value v L(0+).
e) Write the expression for iL(t ) for t ≥ 0.
10 Ω 24 V 120 Ω 40 Ω t=0 20 Ω 7H
i L(t) +
- Problem 5:
Two loads are connected in parallel as shown. Given that:
Load A : Absorbs 25 kVA at 0.96 pf lagging.
Load B: Absorbs 75 kW at 0.8 of leading.
The impedance of the line supplying the loads is resistive and equals 100 ? , and the voltage at the
load is 200 Vrms.
a) What is complex power absorbed by load A?
b) What is complex power absorbed by load B?
c) What is the total complex power absorbed by the two combined loads
d) What is the average power absorbed by the line ?
+ + Vsupply Vload - - Load
A Load B ...
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- Spring '09
- Electrical Engineering, Resistor, Electrical impedance, Power factor