ELECTRIC CIRCUITS
ECSE-2010
Spring 2003
Class 1
ASSIGNMENTS DUE
•
Today (Monday):

•
Activities 1-1, 1-2, 1-3 (In Class)
Tuesday/Wednesday:

•
Activities 2-1, 2-2 (In Class)
Thursday:
•
•
•
Will do Experiment 1; Report Due Jan 27
Will also introduce PSpice
Activity 3-1 (In Class)
Bill Jennings
• Professor, ECSE
• Former Vice Provost, Professional and
Distance Education
• Former Chair, ECSE
• Former Vice Provost, Computing &
Information Technology
• Currently On Leave, But Teaching
 Here Mondays, Wednesdays, Thursdays
CONTACT INFORMATION
•
•
•
•
Office: JEC 6036
Phone: 276-6083
Email: jenniw@rpi.edu
Office Hours:
 2-4 Wednesdays, JEC 4104 (Studio)
• In addition: I will usually be in my
office from 2-4 on Mondays and
Thursdays
TEXTBOOK
• Introduction to Electric Circuits
 Richard Dorf and James Svoboda
• Has Student Resources CD




Electronic Teaching Assistant (ETA)
Electric Circuits Workout
Circuit Design Lab
Interactive Illustrations
• Will Also Use ILM’s Created by the
Academy for Electronic Media
SUPPLEMENT
• Supplement for Spring 2003:




Activities
Notes on Using PSpice
Computer Projects
Experiments
• Purchase by Next Class:
 Priscilla Magilligan, JEC 6049
 $5
• Bring to Class Every Day
 Will also need Text occasionally
WEBSITE
• http://www.ecse.rpi.edu
 Academics
 Course Homepages
 Spring 2003-ECSE 2010
•
•
•
•
General Information and Syllabus
Solutions to Homework Assignments
Sample Exams and Solutions
Class Powerpoint Slides
 B&W - 6 slides per page
• PDF Files – Use Adobe Acrobat
ELECTRIC CIRCUITS
• Section 1: Prof. Millard (Administrator)
 Monday, Tuesday, Thursday 10-12
• Section 2: Prof. Jennings
 Monday, Wednesday, Thursday, 4-6
• Section 3: Prof. Nagy
 Monday, Tuesday, Thursday, 2-4
FORMAT
• Mini-Lectures: Come Prepared
• In-Class Activities: Work Together,
Some Short, Some Long, Graded
• Experiments: Start in Class, Due Later,
Reports Required, Graded
• Computer Projects: Same
• Homework: Due Each Week, Graded
• Graded Papers: Returned in Section 2
Slot in Boxes on Wall in JEC 4104
PARTNERS/TEAMS
• Choose a Partner by Thursday
 2-Person Teams
• Most of the Work Done by Team
 Homework, In-Class Activities, Experiments,
Computer Projects
 BUT! Submit 2 Papers; Will be separately graded
• All Exams done Separately
 3 Exams plus Final Exam
• Work Together and Help Each Other
GRADING
•
•
•
•
•
•
•
•
In-Class Activities: Daily
Homework:
14
Experiments:
11
Computer Projects:
5
Exam I:
Exam II:
Exam III:
Final Exam
10%
15%
15%
10%
10%
10%
10%
20%
100%
GRADING
•
•
•
•
•
•
•
•
Activities:
0 5 10 points
Homework:
0 -15 points
Experiments:
0 - 15 points
Computer Projects: 0 - 10 points
Exam I:
0 - 100 points
Exam II
0 - 100 points
Exam III:
0 - 100 points
Final Exam
0 - 150 points
GRADE RECORDS
• Keep Your Own Records
 Activities, Experiments
 Computer Projects, Exams
• Check With Priscilla Magilligan
 Official Record Keeper for All Sections
 JEC 6049
FINAL GRADES
• Grades Depend on Class Statistics
 All Sections Grouped Together
• Typically:




> 90%
> 80%
> 70%
> 55%
A
B (B/C set at median)
C
D
ELECTRIC CIRCUITS
• Problem Solving Techniques:
 Circuits and Other Systems
 Modeling, Analysis, Simulation, and
Experimentation of Circuits
• Vocabulary:

Language of EE’s/CSE’s
• Fundamentals:
 Concepts EE’s/CSE’s Need to Know
 Foundation for Further Courses
COURSE STRUCTURE
• Unit I: Chapters 1, 2, 3, 4, 5
 Circuit Variables and Elements
 Techniques for Analyzing Resistive Circuits
 Circuit Theorems
• Unit II: Chapters 6, 7, 8, 14, 9





Operational Amplifiers
Circuits with Inductors and Capacitors
Response of 1st Order Circuits
Laplace Transforms and Techniques
Response of 2nd Order Circuits
COURSE STRUCTURE
• Unit III: Chapters 10, 11, 12, 13
 AC Steady State Circuit Analysis
 AC Power and 3 Phase Circuits
 Frequency Response
• Unit IV: Chapters 13, 14, 16
 Bode Plots
 Complete Response using Laplace Transforms
 Filter Circuits
ANALYSIS TECHNIQUES
•
•
•
•
•
•
•
Series/Parallel Reduction
Current and Voltage Dividers
Equivalent Resistance/Impedance
Node/Mesh Equations
Linearity and Superposition
Source Conversions
Thevenin/Norton Equivalent Circuits
VARIABLES
• Never Solve a Real Circuit:
 Solve Circuit Model
• Consider a Flashlight:
 Battery, Bulb, Connections, Switch, Case
• Model for Battery: Ideal Voltage Source
 Battery is a DC (Direct Current) Voltage Source
• Model for Connections: Ideal Wires
 No Energy Loss
• Model for Bulb: Ideal Resistor
 Linear Relationship between Current and Voltage
MODEL FOR FLASHLIGHT
Switch
Ideal Wires
Battery
1.5 V
i

Light Bulb
v
1.0 

Ground (0 V)
CURRENT
• Current = i = Flow of Charge
 i = dq/dt; coulombs/sec = Amps; A
• Current has Magnitude and Direction
• Direction of Current Arrow = Direction
Positive Charge Would Flow
• Current Flows in a Complete Path
• Assume Direction for i: Calculate i
 if i > 0 => Correct Assumption
 if i < 0 => Current Flows Other Way
VOLTAGE
• Voltage = v = Electrical Potential Energy
Difference/Unit Charge => Potential
Difference
 Potential Difference Drives Charge
 v = dw/dq; joules/coulomb = volts; V
 Must define positive (+) and negative (-) terminals
for voltage
 Will use passive/active conventions to do this
 Assume polarity for v; If v < 0 => terminals are
reversed
POWER
• Power = p = Electrical Energy/Time





p = dw/dt = dw/dq x dq/dt = v x i
Units of p = joules/sec = watts; W
Will use both Active and Passive Devices
Passive Devices Absorb Power
Active Devices MAY Supply Power
ENERGY
• Energy = w = Electrical Energy






w   p dt
Units of w = watt-sec (commonly kW-hr)
Energy may be Absorbed or Supplied
Passive Devices Absorb Energy
Active Devices MAY Supply Energy
Will use Power more frequently than Energy
UNITS
i
1012 Tera
TA
109 Giga
GA
106 Mega MA
103 kilo
kA
100
A
10-3milli
mA
10-6micro
uA uV
10-9nano
nA
10-12 pico
pA
v
TV
GV
MV
kV
V
mV
uW
nV
pV
p
TW
GW
MW
kW
W
mW
nW
pW
CONSISTENT SETS OF UNITS
i
A
mA
A
uA
v
V
V
mV
kV
etc.
p
W
mW
mW
mW
PASSIVE CONVENTION
• Passive Element: Absorbs Energy
 Gets Hot; Power Absorbed > 0
 Passive Element is called a LOAD
• i Flows from + to - in Passive Element
• Assume Polarity for v:
 Determines Direction of i in Passive Element
• OR: Assume Direction for i
 Determines Polarity of v in Passive Element
• i and v will have same sign
 p = v x i > 0 = Power Absorbed
PASSIVE CONVENTION
p  i x v  Power Absorbed

i
Passive
Element
v

Current flows from  to 
ACTIVE CONVENTION
• Active Element MAY Supply Energy
 Active Element is called a SOURCE
 If only 1 Source; it MUST supply energy
 If more than 1 Source; some may supply
energy; some may absorb energy
• i Flows from - to + for Active Element
• p = v x i > 0 => Power Supplied
• Power Supplied = Power Absorbed
 In any Circuit
ACTIVE CONVENTION

v
p  i x v  Power Supplied
Active
Element
i

Current flows from  to 
CIRCUIT

v

Active
Element
i
p  i x v  Power Supplied
i
Passive
Element

v

p  i x v  Power Absorbed
Current Flows in Closed Path
ACTIVITY 1-1
i

v

v  5 kV
i  4  A
ACTIVITY 1-1
• A: Positive Current Flows from + to - :
 A Must be a Passive Element => LOAD
• B: Positive Current Flows from - to + :
 B Must be an Active Element => SOURCE
• Power Supplied = p = v x i:
 p = 5000 volts x 4 microamps = 20 mWatts
IDEAL VOLTAGE SOURCE
i
i
OR
V0
Any Ideal Voltage Source
(DC, AC, etc)
V0
Ideal DC Voltage Source
(Battery)
IDEAL VOLTAGE SOURCE
i
Constant Voltage
Independent of Current
V0
v
IDEAL CURRENT SOURCE

I0
vv


Any Ideal Current Source
(DC, AC, etc)
No Special Symbol for DC
IDEAL CURRENT SOURCE
i
I0
Constant Current
Independent of Voltage
v
IDEAL SOURCES
• Ideal Voltage Source:




Model = Circle with + and - voltage terminals
Voltage always the same across voltage source
Can supply any current
Current through voltage source can be anything
• Ideal Current Source:




Model = Circle with Current Arrow
Current always the same from current source
Can supply any voltage
Voltage across current source can be anything
ACTIVITY 1-2
• Circuit Elements are usually
characterized by Device Curve:
 Plot of v vs. i OR i vs. v
• Which One is an Ideal Voltage Source?:
 Device #3; A Negative Voltage Source
• Which One is an Ideal Current Source?:
 Device #5; A Positive Current Source
ACTIVITY 1-2
• Which One is a Passive Device?:
 Passive Device must have p > 0; p = v i
 Device #2 is a Passive Device
 Non-linear Passive Device
• Which Ones are Active Devices?:
 Active Device can have p > 0 or p < 0
 Device #1; Device #4; Device #6
RESISTORS
• Resistor is the Most Common Passive
Element Used in Circuits:
 Symbol = R
 Circuit Model =
R  Resistance 
R
L
(for cylinder);
A
  Resistivity of Material, L  Length,
A  Cross-sectional Area
OHM’S LAW
i

V0
R
v

Vary V0
Measure v and i
OHM’S LAW

v




v
Slope   R
i
i
R  Resistance
Measured in Ohms ()
OHM’S LAW
• Important Concept - Will Always Use
• Plot of v vs. i for Resistor is LINEAR
 Goes through v = 0, i= 0
•
•
•
•
•
Slope of Line = v/i = R;
Units of R: Ohms = volts/amp ()
Equation of Straight Line Thru Origin:
=> v = i R
=> Ohm’s Law
OHM’S LAW
i
v  iR
v
i
R
v
R
i

R
v

ACTIVITY 1-3

12 V
i
3 k .5 mA
v

a
b
4 M
ACTIVITY 1-3
• 1-3a:
 i = 12 V/3k = 4 mA
 p = 12 V x 4 mA = 48 mW = v i = v2/R = i2 R
• 1.3b:
 i = - 0.5mA => v must be negative
 v = i R = - 0.5mA x 4 Mohms= - 2 kV
 p = v i = v2/R = i2 R = 1 W