ECE 201 Spring 2009 Exam 2 March 10 2009 Division 0101 Elliott 9 30am Division 0201 Capano 10 30 am Division 0301 Jung 11 30 am Division 0401 Capano 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 6 If extra paper is needed use back of test pages 7 Cheating will not be tolerated Cheating in this exam will result in an F in the course 8 If you cannot solve a question be sure to look at the other ones and come back to it if time permits 9 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 outcomes i iii iv and viii 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 Outcome i is a repeat We use this outcome result only if you did not satisfy it previously Course Outcome Minimum correct answers required to satisfy course outcome i 2 6 5 3 iii 1 2 5 7 8 5 3 iv 7 13 7 3 viii 1 1 1 If you fail to satisfy any of the course outcomes don t panic There will be more opportunities for you to do so Potentially useful formulas are x t x x t o x e Exam Questions of Questions t t o L R 1 RC 1 The network shown delivers power to a load resistor RL Determine the resistor RL that absorbs the maximum power from the source and the power absorbed 1 RL 6 PL opt W 6 2 6 3 3 6 1 5 4 10 22 5 5 10 15 6 10 10 7 25 56 25 8 25 12 5 9 25 10 2 Determine the equivalent capacitance of the network shown 1 21 2 F 2 25 0 F 3 20 83 F 4 4 0 F 5 1 13 F 6 4 81 F 7 30 83 F 8 31 2 F 9 35 0 F 2 3 The 0 1A cos 1000t current source drives the single loop network shown The initial capacitor voltage is zero vc 0 0 Determine the voltage VL t across the inductor 1 4V sin 1000t 2 3V sin 1000t 3 2V sin 1000t 4 1V sin 1000t 5 0 6 1V sin 1000t 7 2V sin 1000t 8 3V sin 1000t 9 4V sin 1000t 4 Find vout in V Vout at t 0 is zero 1 sin t 2 2 sin t 3 3 sin t 5 6 sin t 6 36 sin t 7 72 sin t 3 4 4 sin t 5 Find the instantaneous energy stored in the 3H inductor at t 0 s in J 1 1 2 2 3 3 5 5 6 6 7 7 4 4 6 A voltage source vs t 10V cos 20t drives the capacitor as shown Determine the voltage Vout t 1 4V cos 20t 2 3V cos 20t 3 2V cos 20t 4 1V cos 20t 5 0 6 1V cos 20t 7 2V cos 20t 8 3V cos 20t 9 4V cos 20t 4 7 For the circuit shown below find R t for t 0 Assume iL 0 10mA Hint Calculate iL t first 30 R t 60 40 mH 20 1 0 1 e t 0 01 V 2 0 1 e t 0 001 V 3 0 2 e t 0 01 V 4 0 2 e t 0 001 V 5 0 3 e t 0 01 V 6 0 3 e t 0 001 V 7 0 3 e t 0 01 V 8 Find the value for vL 0 in V 1 12 2 20 3 8 4 16 5 4 6 24 7 0 5 9 For the circuit shown below assume the switch has been closed for a long time before it opens at t 0 Find vc 0 1 6V 2 6V 3 0 4 5 56V 5 4V 6 18V 7 10 8V 10 In the circuit below vc t 20 10e 0 4t V for t 0 Also ic t 0 4e 0 4t for t 0 Find the value of R in 1 25 2 8 3 36 5 5 6 15 7 48 6 4 4 11 Find the inductor current for t 0 in A 1 15 13e 0 1t 2 2 5e 0 4t 4 2 5e 2 5t 5 5 3e 10t 3 3 5e 0 1t 6 15 5e 10t 7 3 5e 2 5t 12 For the circuit shown below find zero input response source free response and zero state response for t 0 in t 10 u t 20 u t 1 2 3 4 5 6 7 8 C t C t C t C t C t C t C t C t Zero input response Source free response 8 e t 0 0016 8 e t 0 0016 8 e t 0 0016 8 e t 0 0016 16 e t 0 0016 16 e t 0 0016 16 e t 0 0016 16 e t 0 0016 Zero state response 16 1 e t 0 0016 16 1 e t 0 0016 16 1 e t 0 0016 16 1 e t 0 0016 8 1 e t 0 0016 8 1 e t 0 0016 8 1 e t 0 0016 8 1 e t 0 0016 7 13 The switch in the figure shown below is originally open at t 0 It closes when C 8V and opens when C 6V Assume C 0 0 4 k 10 V C t 0 5 mF 1 k The capacitor voltage is 10V 1 e 0 5t 2V 6Ve 2 5 t t a vc t 10V 4Ve 0 5 t t b 0 t ta ta t tb 8V tb t tc 6V as plotted to the right Calculate t b t a 1 0 062 s 2 0 162 s 3 0 262 s 5 0 462 s 6 0 562 s 7 0 662 s 8 4 0 362 s
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