ECE 201 – Spring 2008 Final Exam April 29, 2008 Division 0101: Qi (7:30am) Division 0201: Elliott (12:30 pm) Division 0301: Capano (2:30 pm) Division 0401: Jung (3:30 pm) Instructions 1. DO NOT START UNTIL TOLD TO DO SO. 2. Write your Name, division, professor, and student ID# (PUID) on your scantron sheet. 3. This is a CLOSED BOOKS and CLOSED NOTES exam. 4. There is only one correct answer to each question. 5. Calculators are allowed (but not necessary). Please clear any formulas, text, or other information from your calculator memory prior to the exam. 6. If extra paper is needed, use back of test pages. 7. Formulas are given on the final page of this exam. 8. Cheating will not be tolerated. Cheating in this exam will result in an F in the course. 9. If you cannot solve a question, be sure to look at the other ones and come back to it if time permits. 10. As described in the course syllabus, we must certify that every student who receives a passing grade in this course has satisfied each of the course outcomes. On this exam, you have the opportunity to satisfy all outcomes. (See the course syllabus for a complete description of each outcome.) On the chart below, we list the criteria we use for determining whether you have satisfied these course outcomes. You only need to satisfy the outcomes once during the course, so any outcomes that you satisfied previously will remain satisfied, independent of your performance on this exam. Course Outcome Exam Questions Minimum correct answers required to satisfy the course outcome I 1, 10, 17-19 3 ii 5-9 3 iii 2-4, 11, 13, 14, 18, 19 4 iv 11-14, 16 3 v 17-21 3 vi 22 1 vii 23-24 1 viii 25 1 ix 15, 16, 21 2 11. In the network shown below there is an element in each branch. Find the current I. (Hint: Gaussian surface) (1) -3A (2) -2A (3) -1A (4) 0A (5) 1A (6) 2A (7) 3A 1A 2AI 2A 6A3A 2. For the circuit shown below, find the output voltage, VOUT. (1) 5V (2) 10V (3) 15V (4) 20V (5) 25V (6) 30V (7) 35V (8) 40V 20mA 10kΩ10kΩ20V 10kΩ 5kΩ 5kΩ VOUT 10kΩ 23. For the following network of resistors, each of value R, determine the equivalent resistance Req. R (1) 1/8 R (2) 1/4R (3) 3/8 R (4) 1/2 R (5) 5/8 R (6) 3/4 R (7) 7/8 R (8) R 4. The output voltage Vo can be expressed in terms of the values of the independent sources as follows: . For V1 = 20 V and I2 = 8 A, Vo is (in V): o1V = AV + BI2 5Ω10ΩI2+-10Ω-+VoV110Ω (1) 1 (2) 5 (3) 10 (4) 15 (5) 18 (6) 25 (7) 36 (8) 48 35. Which one of the following equations relating VA, VB and VX is correct for the circuit shown? (1) AABXVVVV030 20 5−++ΩΩ = (2) AXBVVV10V10V 030 20 15+−+ −=ΩΩ Ω (3) BAXV10VV V0.5A 015 5 20−++ − =ΩΩ (4) BXXV10VV V0.5A 015 5 20+++ − =ΩΩ (5) AABVVV0.5A 030 20−++ΩΩ= 6. In the following circuit, mesh currents I1, I2 and I3 are as labeled. Which one of the following equations is correct for the circuit? (1) A1II(10 ) 10V 02Ω+−= (2) ()A1II10 10V 02Ω−−= (3) ()A1II10 10V 02Ω++= (4) ()()31 3I I 20 15V I 20 0−Ω− + Ω = (5) ()()()12 31I 10 10V I 15 15V I I 20 0Ω++ Ω++− Ω= 47. For the network shown below, find Ieq [A] and Req [Ω] using source transformation. (1) Ieq = 8/3, Req = 4 (2) Ieq = 8/3, Req = 3 (3) Ieq = 3, Req = 3 (4) Ieq = 3, Req = 4 (5) Ieq = 7/3, Req = 3 (6) Ieq = 7/3, Req = 4 (7) Ieq = 3, Req = 8 8. For the following circuit, determine the value Vth and Rth of the Thévenin equivalent network. thV = thR = (1) 6 V 5 Ω (2) 6 V 20 Ω (3) 6 V 30 Ω (4) 7.5 V 6.67 Ω (5) 7.5 V 20 Ω (6) 7.5 V 30 Ω (7) 8 V 5 Ω (8) 8 V 6.67 Ω (9) 8 V 20 Ω 59. 6 Ω v1 3 Ω 3 v1 3 Ω RTH Find the Thévenin equivalent resistance RTH for the network above. (1) -1 Ω (2) 0 Ω (3) 1 Ω (4) 2 Ω (5) 3 Ω (6) 5 Ω (7) 6 Ω (8) 9 Ω 610. The current i(t) onto a 1 μF capacitor is shown below. Determine the voltage vc(t). 711. For the network shown below, find iL(t) for t > 0. (1) 0.3+0.7e-t/0.000001 [mA] (2) 0.3-0.7e-t/0.000001 [mA] (3) -0.3+0.7e-t/0.00001[mA] (4) –0.3-0.7e-t/0.00001 [mA] (5) 0.2+0.5e-t/0.00005 [mA] (6) 0.2-0.5e-t/0.00005 [mA] (7) -0.2+0.5e-t/0.00005 [mA] 12. t=0 A VC(t) 0.25 F B 10 A 16 HAfter the switch turns from position A to B at t=0, what is the angular frequency of oscillation, ω, of the voltage Vc(t)? (1) 0.1 rad/s (2) 0.25 rad/s (3) 0.0625 rad/s (4) 0.5 rad/s (5) 2 rad/s (6) 4 rad/s (7) 10 rad/s 813. In the following network, the 10V source turns on and the switch opens at t = 0. Determine . ()Rv0− (1) 15 V (2) 10 V (3) 5 V (4) 0 V (5) -5 V (6) -10 V (7) -15 V 14. In the circuit shown in the previous problem (Problem 13), determine . ()Rv0+ (1) 15 V (2) 10 V (3) 5 V (4) 0 V (5) -5 V (6) -10 V (7) -15 V 915. Find υout(t) assuming ideal OP-amp behavior. (1) 4cos(ωt) (2) 8cos(ωt) (3) 12cos(ωt) (4) -4cos(ωt) (5) -8cos(ωt) (6) -12cos(ωt) (7) 0 2 kΩ 1 kΩ2 kΩ4 kΩ 1 kΩ 4 kΩυIN(t)=2cos(ωt)V 1016. In the following figure, vs(t) = – 6u(-t) + 3u(t). What is vc(t) (in V) for t > 0? [Note: We are not asking for vout in this problem!] 2 F100 Ω 150 Ω 50 Ω (1) t10026e−−+ (2) t20026e−− (3) t1004 12e−−− (4) t100412e−− (5) t5026e−−+ (6) t504 12e−− (7) t2004 12e−− (8) t2004 12e−−+ 1117. 10∠°A j3 Ω V1 VS –j V16 Ω Using KVL, the phase voltage VS, in Volts, is: (1) 6 + 2j (2) 6 – 2j (3) 6 + 3j (4) 6 – 3j (5) 3 + 3j (6) 3 – 3j (7) 3 + 6j (8) 3 – 6j 18. Find the sinusoidal steady state output voltage, υOUT(t). (1) 9cos(1000t) (2) 3cos(1000t) (3) 9cos(1000t+30°) (4) 3cos(1000t+30°) (5) 9cos(1000t+150°) (6) 3cos(1000t+150°) (7) 3cos(1000t+180°) 1mH120Ω 1mF1mH~υIN(t)=12cos(1000t+30°) 40Ω 1mFυOUT(t) 1219. Determine the value of C for which the input current Iin in the circuit below would become zero: _ + 5 Ω Iin C 110 cos (106 t) V 100 μH (1) 1 nF (2) 2 nF (3) 3 nF (4) 4 nF (5) 5 nF (6) 0 (7) 10 nF 1320. Consider the following circuit. Vin and Vout are the phasor representations of the input and output voltages, respectively. The input Vin is a sinusoidal signal of frequency ω in its steady-state. 1mHVin Which
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