INC 112 Basic Circuit Analysis Lecturer Assistant Prof. Dr. Poj Tangamchit

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

Freshmen’s Requirements ComputerINC160 SoftwareINC151 CircuitINC112

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

Scoring & Grading Midterm Exam35% Final Exam35% Homework, assignment20% Quiz (Pop quiz)10% Grading follows the faculty of Engineering’s standard procedure.

Homework & Quiz Homework takes time. Allocate 6-12 hours each week for it. Students need self-study outside class time.

Assignment

Course Webpage Lecture Slides Homework Homework/ Quiz Solutions Announcements

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

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

Electricity Electricity is a result from the flow of electrons. = electron electricity Note: Electricity flows in the opposite direction of electron flow.

Electric Current vs. Electron Current = Atom Structure electricity

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

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. strong (fast, high kinetic energy) amount of water Voltage Current High Voltage Low Voltage

Imagine the water power at the outlet

Electric Potential ( ศักย์ไฟฟ้า ) 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

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.

Voltage ( ความต่างศักย์ ) Voltage is a difference of electric potential between 2 points Unit: Volt Compare to the height of 2 water drops

Electric Current ( กระแส ) Low currentHigh current

Electric Current Unit Unit: Ampere, Amp (A) Note: Both current and voltage have directions

What is Circuit Analysis about? To calculate voltage or current at some points and some time in electric circuits

Course Overview Constant voltage Constant current Midterm Rules: Ohm’s law Kirchoff’s law Techniques: Mesh Analysis Node Analysis Superposition Thevenin/ Norton Circuits Time Voltage Current Voltage Current DC (Direct current)AC (Alternating current) Frequency Transient Response Phasor Concept

Topics Week 1: Introduction to Electricity, Simple DC circuits, Ohm’s law Week 2: Kirchoff’s voltage law, Kirchoff’s current law Week 3: Nodal Analysis Week 4: Mesh Analysis Week 5: Thevenin’s theorem Week 6: Norton’s 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

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

Independent Voltage Source Independent Current Source Resistor Ground Symbol Electric wire

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)

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 Ohm’s 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.

Three Measurements of Electricity VoltageVolt (V) CurrentAmpere (A) ResistanceOhm (Ω)

Prefix Giga (G)10 9 Mega (M)10 6 Kilo (K)10 3 Centi (c)10 -2 Milli (m)10 -3 Micro (μ)10 -6 Nano (n)10 -9 Pico (p)10 -12

Simple DC Circuit Current

Metaphor Current Increasing V is compared to ? Increasing R is compared to ?

Ohm’s Law V = IR Voltage (Volts) = current (Amperes) x resistance (Ohms) 2A x voltsx+4 volts 2Ω2Ω for using with a resistor only Note: Electric wire has a resistance of 0 ohms

Electric Current 1A Every point in the circuit has current = 1A

Electric Voltage x + 1 Volts x Volts

Ground Ground = reference point always have voltage = 0 volts 1 Volts 0 Volts

Electric Voltage (2) 1 Volts 0 Volts

Electric Voltage (3) 1 Volts 0 Volts 1 Volts

Negative Voltage and Current + 2 volts - -2 volts + Same as 1 A-1 A

Power Symbol P has a unit of Watt P = VI +V-+V- I Absorb power -V+-V+ I Generate power

Passive Sign Convention Absorb power: Power has a sign + Generate power: Power has a sign -

Example 2.5mA 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

Direction of Voltage & Current on Resistors + - Resistor always absorb power. Therefore, it always have current flow through it from high voltage pin to low voltage pin. - + or