INC 112 Basic Circuit Analysis

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INC 112 Basic Circuit Analysis

• Lecturer
• Assistant Prof. Dr. Poj Tangamchit

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About the Instructor
Office CB40603 (CB4 6th floor) Control System
and Instrumentation Eng. (INC) Tel
x-9094 E-mail poj.tan_at_kmutt.ac.th Research
Interest Robotics, Artificial Intelligence
(AI) Lecture Self-lecture. Reading material
before coming to class is encouraged.
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Freshmens Requirements

• Computer INC160
• Software INC151
• Circuit INC112

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Course Details

• 3 Credits
• Class time 3 hours / week
• Review Homework 6 hours/week
• E-learning material (DVD) is provided

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Scoring Grading
Midterm Exam 35 Final Exam 35 Homework,
assignment 20 Quiz (Pop quiz) 10
Grading follows the faculty of Engineerings stand
ard procedure.
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Homework Quiz
Homework takes time. Allocate 6-12 hours each
week for it. Students need self-study outside
class time.
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Assignment
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Course Webpage
http//www.inc.eng.kmutt.ac.th/inc112

• Lecture Slides
• Homework
• Homework/ Quiz Solutions
• Announcements

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Textbook
Engineering Circuit Analysis, 7th edition
McGrawHill William H. Hayt Jr.,Jack E.
Kemmerly,Steven M. Durbin
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How to read a Textbook

• Book Overview
• Read Index
• Think about what should be in each chapter
• Think about what each chapter relate to each
  other
• Chapter Focus
• Read the title of each section, Guess what it
  will say
• Look at pictures and description
• Read equations and Math parts
• Reread the section that you want to know more

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Electricity
Electricity is a result from the flow of
electrons.
electricity
Note Electricity flows in the opposite
direction of electron flow.
electron
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Electric Current vs. Electron Current
-

-
Atom Structure
-

-
-

-
-


-
-
-

electricity
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Metaphor
Electricity is similar to water flow.
Water flows from high level to low level.
Electricity flows from high voltage to low
voltage.
High Voltage
Low Voltage
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Measurement of Electricity
Since we use electricity to do work for us,
how Can we measure its energy? How can we
measure the water power? Think about a water gun.
High Voltage
Low Voltage
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Imagine the water power at the outlet
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Electric Potential (??????????)
Which water drop has more impact force at the
ground?
Potential Energy (Height)
transform
Kinetic Energy (Velocity)
Electric potential can be compared with the
height of the water drop from the reference ground
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Ground Reference Point
Normally, we measure height compared to the sea
level. Also, electric potential at a point can
be measured compared to the electric potential at
the ground.
Unit Volt (V)
Electric potential, or voltage has a unit volt.
Ground always has 0 volts.
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Voltage (?????????????)
Voltage is a difference of electric potential
between 2 points
Unit Volt
Compare to the height of 2 water drops
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Electric Current (?????)
Low current
High current
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Electric Current Unit
Unit Ampere, Amp (A)
Note Both current and voltage have directions
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What is Circuit Analysis about?
To calculate voltage or current at some
points and some time in electric circuits
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Course Overview
DC (Direct current)
AC (Alternating current)
Circuits
Voltage Current
Voltage Current
Constant voltage Constant current
Midterm
Time
Phasor Concept
Rules Ohms law Kirchoffs law
Techniques Mesh Analysis Node Analysis Superposit
ion Thevenin/ Norton
Frequency
Transient Response
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Topics
Week 1 Introduction to Electricity, Simple DC
circuits, Ohms law Week 2 Kirchoffs voltage
law, Kirchoffs current law Week 3 Nodal
Analysis Week 4 Mesh Analysis Week 5 Thevenins
theorem Week 6 Nortons theorem, Maximum power
transfer theorem Week 7 Introduction to AC
circuits and components Week 8 Midterm
Exam Week 9 Transient response of RL
circuits Week 10 Transient response of RC
circuits Week 11 Transient response of RLC
circuits Week 12 Phasor concept Week 13 Phasor
circuit analysis Week 14 AC Power, Frequency
response Week 15 Final Exam
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Components

• Electric sources
• Independent Sources voltage, current
• Dependent Sources voltage, current
• Resistors
• Measurement Devices
• Ammeters measure current
• Voltmeters measure voltage
• Ground reference point
• Electric Wire

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Symbol
Independent Voltage Source
Independent Current Source
Resistor
Ground
Electric wire
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General Rules

• All points on a same electric wire have the same
  voltage.
• A voltage source always have voltage difference
  of its pins equal to its value.
• A current source always have current pass
  through it equal to its value.
• Ground always has zero voltage. (0 volts)

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Electric Flow Rule

• Electric current flows from high voltage to low
  voltage when there is a path.
• Electric current can freely pass through
  electric wire.
• Electric current can flow through a resistor
  with the amount according to Ohms law.
• Electric current can flow through a voltage
  source with the amount depended on other
  components in the circuit.
• Electric current can flow pass a current source
  according to its value.

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Three Measurementsof Electricity
Voltage Volt (V) Current Ampere
(A) Resistance Ohm (?)
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Prefix
Giga (G) 109 Mega (M) 106 Kilo (K) 103 Centi
(c) 10-2 Milli (m) 10-3 Micro (µ) 10-6 Nano
(n) 10-9 Pico (p) 10-12
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Simple DC Circuit
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Metaphor
Increasing V is compared to ? Increasing R is
compared to ?
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Ohms Law
for using with a resistor only
V IR Voltage (Volts) current (Amperes) x
resistance (Ohms)
2A
2O
x volts
x4 volts
Note Electric wire has a resistance of 0 ohms
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Electric Current
1A
1A
1A
Every point in the circuit has current 1A
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Electric Voltage
x 1 Volts
x Volts
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Ground
Ground reference point always have voltage 0
volts
1 Volts
0 Volts
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Electric Voltage (2)
1 Volts
0 Volts
0 Volts
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Electric Voltage (3)
1 Volts
1 Volts
0 Volts
1 Volts
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Negative Voltage and Current
2 volts -
- -2 volts
Same as
1 A
-1 A
Same as
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Power
Symbol P has a unit of Watt
P VI
I
V -
Absorb power
I
- V
Generate power
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Passive Sign Convention
Absorb power Power has a sign
Generate power Power has a sign -
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Example
DC source generates power 10V -2.5mA -
25mW Resistor absorbs power 10V 2.5mA 25mW
Note Resistors always absorb power but DC source
can either generate or absorb power
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Direction of Voltage Current on Resistors
or
-
-
Resistor always absorb power. Therefore, it
always have current flow through it from high
voltage pin to low voltage pin.