ECE 201 Section 4 Lecture 16 Prof Peter Bermel February 17 2012 Exam 1 Question 9 2 17 2012 ECE 201 4 Prof Bermel Exam 1 Question 10 In the following circuit R1 R2 R3 1 gm 1S Use loop mesh analysis to express I1 in terms of IS 1 2 3 4 5 6 7 8 2 17 2012 I1 0 1IS I1 0 5IS I1 0 75IS I1 1 25IS I1 1 5IS I1 2IS I1 2 5IS I1 3IS ECE 201 4 Prof Bermel Exam 1 Question 11 Using superposition find the value for ix in the circuit below in A 3W 4W 40 V 5A 6W ix 1 1 5 5 2 17 2012 2 2 6 6 3 3 7 7 ECE 201 4 Prof Bermel 4 4 8 8 Exam 1 Question 12 What are the coefficients and in 1 2 3 4 5 6 7 1 5 1 1 5 3 1 15 2 1 5 1 1 5 1 1 15 3 1 30 2 2 17 2012 30 10 15 vo Vs 60 Is 5 ECE 201 4 Prof Bermel Exam 1 Question 13 Two non ideal voltage sources are connected in parallel The first source has voltage V1 and resistance R1 The second source has voltage V2 and resistance R2 The parallel connection is a non ideal voltage source with the following voltage and resistance 1 2 3 4 5 6 7 8 V1 V2 R1 R2 V1 V2 R1R2 R1 R2 R2V1 R1V2 R1 R2 R1R2 R1 R2 R2V1 R1V2 R1 R2 R1 R2 V1V2 V1 V2 R1 R2 V1V2 V1 V2 R1R2 R1 R2 R1V1 R2V2 R1 R2 R1R2 R1 R2 R1V1 R2V2 R1 R2 R1 R2 2 17 2012 ECE 201 4 Prof Bermel R2 R1 V1 V2 Power in Inductors Since the instantaneous power in an inductor The energy stored between to and t1 is 1 2 For ac wave with period T 1 f 0 if for integer m 2 17 2012 ECE 201 4 Prof Bermel Introduction to Capacitors Capacitors are circuit elements capable of storing charge Voltage drop proportional to stored charge V Q C or Q CV Capacitance C in units of C V or F Current flow given by 2 17 2012 ECE 201 4 Prof Bermel Calculating Capacitance Capacitance determined by geometry and materials present Calculated using Gauss Law For parallel plate capacitor E Q A V d thus In vacuum 8 854 10 F m 2 17 2012 ECE 201 4 Prof Bermel Calculating Capacitance For two capacitors in parallel 0 12 12 0 12 For N capacitors in parallel 5 12 3 4 46 2 17 2012 ECE 201 4 Prof Bermel C1 C2 Calculating Capacitance For two capacitors in series 0 12 12 1 1 1 12 For N capacitors in parallel 5 1 1 3 12 4 46 2 17 2012 ECE 201 4 Prof Bermel C1 C2 Example 1 What is the current produced by plugging a 100 F capacitor into the wall How much power is dissipated by it 160 sin 120 t 2 17 2012 100 F ECE 201 4 Prof Bermel Solution 160 sin 120 t 100 F 100 89 160 120 cos 120 1 92 cos 120 1 92 cos 120 160 sin 120 153 6 sin 240 2 17 2012 ECE 201 4 Prof Bermel Example 2 What is the current flow in this circuit as a function after the switch is closed at time t 0 3 k 12 V 100 F 2 17 2012 200 F ECE 201 4 Prof Bermel Solution 3 k 12 V 100 F Applying KVL 2 17 2012 200 F 12 3 D 100 200 89 12 300 89 3 D H I 12 300 89 I 3 D ECE 201 4 Prof Bermel Solution 3 k 12 V 100 F 200 F H J 0 0036 I 0 0036 0 9 K ln 0 0036 M N O M M 1 N O N O t 0 300 89 3 D 2 17 2012 ECE 201 4 Prof Bermel Here Qf 3 6 mC T 0 9 s Io 4 mA Solution Current mA 4 3 5 3 2 5 2 1 5 1 0 5 0 2 2 17 2012 1 0 1 ECE 201 4 Prof Bermel 2 3 4 Power Energy in Capacitors Instantaneous power given by Energy stored over a time interval to t1 is P P 1 2 2 17 2012 ECE 201 4 Prof Bermel Homework HW 14 solution posted today HW 15 due today by 4 pm in EE 325B HW 16 due Mon DeCarlo Lin Chapter 7 Problem 12 Problem 16 Problem 17 2 17 2012 ECE 201 4 Prof Bermel
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