Engineering 215 Principles of Electrical Engineering Physics 262 Electrical Circuits and Devices
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Transcript of Engineering 215 Principles of Electrical Engineering Physics 262 Electrical Circuits and Devices
Engineering 215Principles of Electrical Engineering
Physics 262Electrical Circuits and Devices
The Electronics Course
Who should take this course?This course is part of the curriculum for
the following disciplines: Physics Engineering PhysicsAerospaceAgriculturalBiological SystemsChemicalCivil
IndustrialElectricalMechanical NuclearOceanPetroleumRadiological Health
What are the course objectives?To be able to identify electrical
components in your everyday life To learn how to interpret electrical
schematicsTo design analog and digital circuitsTo build complex electrical circuitsTo use software for circuit design and
testing
What are the course objectives?To develop troubleshooting techniques To get hands-on experience To learn how to use diagnostic equipmentTo understand the physics of electron flow
at the atomic levelTo improve our mathematics skills
Where do we find electrical circuits? Communications
Radio, internet, telephone, television Data Processing
Desktop computers, servers Automobiles
displays, sensors, motors Home
lighting, heating, appliances Weather Stations
wind speed, precipitation, temperature Power Plants
moving magnets, transformers
Let’s take notes….
The Electronics Course
Chapter 1Introduction
Chapter 1 - IntroductionElectricity
From the word “Elektron” Greek for “amber”
(Meter stick and Cup Demo)
What’s the point? With knowledge about the fundamentals of
electricity we can create circuits that control the flow of electricity.
These circuits can work for us… …and think for us.
What is electricity?
Valence Electron
That’s Electricity!
What is electricity?
Valence Electron
What can multimeters measure?VoltageCurrentResistanceFrequencyCapacitanceOther Functions
AC and DC (Voltages) Open and Closed Circuits Hold
Demos:9V Batteries
Wall OutletBody Resistance
Symbols, Quantities, and Unitsq ivPR
Ohm’s LawV=IR
Electrical PowerP=IV
Resistance QuestionWhat is the resistance of a 100W light bulb?
Today’s PlanTurn in Homework 0 before 5:00pm
In mailbox later or on the front table nowHomework 1
Check email for video
Shocking DemoKey Idea: “Contact Resistance”
9-Volt Batteries Salt Water
Thought Questions: Is water a good conductor? What is de-ionized water?
Inside of a 9 Volt Battery
http://www.youtube.com/watch?v=tr5ZB1eFhwc
http://www.youtube.com/watch?v=s_8n2Qgguto
http://www.youtube.com/watch?v=nzgDffMcsUU (fake)
What is an insulator?a material that does not allow electrons
to flow freelyExamples:
Wood Plastics Ceramics Amber Air
What is a conductor?a material that allows free electron
movementExamples:
Aluminum Gold Copper Most Metals
What is a semiconductor?a class of materials whose electron
conductivity is between that of a conductor and insulator
Examples: Silicon Germanium
Circuit SymbolsResistorCapacitor InductorSwitchUnspecified Circuit Element BatteryBulb
Sketch the circuit for the diagram above using standard circuit symbols.
What is a short circuit? Answer: A low resistance path across the
terminals of an electrical energy source
Sprial Wound Shunt Type Slow Blow Fuse
GFCI
Circuit Beakers
http://home.howstuffworks.com/circuit-breaker2.htm
Electrical Current
Current the rate of flow of charge through a conductor
measured in Amperes (1 A = 1 C/s) Charge of the Electron
e = -1.603 10-19 Coulombs Conventional Current
Direction of flow of positive (+) charges Electron Current
Opposite to that of conventional current
Effect of Electric Currents on the Body 0.001 A can be felt 0.005 A is painful 0.010 A causes involuntary muscle
contractions 0.015 A causes loss of muscle control 0.070 A can be fatal if the current last for more
than 1 second
Electricity & SafetyBody Resistance
100 Ohms (soaked in salt water) 500,000 Ohms (very dry)
How much voltage is fatal if you have dry skin? ...if you are soaked in salt water? “Current Kills”
How can we keep currents low in the lab?
Current Equation
tqi
Current in Amperes (A)
Charge inCoulombs (C)
Time in Seconds (s)
dt)t(dqi Calculus:
Types of ElectricityStatic Electricity - no motion of free
charges
Current Electricity - motion of free charges Direct Current (DC) Alternating Current (AC)
(Plot On Chalk Board)
Homework 1
Any Questions?
VoltageVoltage is the measure of the potential
to move electrons.1 Volt = 1 Joule/CoulombSources of Voltage
Batteries (DC)
Wall Outlets (AC)
V9)t(v
)t120sin (V11 0)t(v
More Circuit Symbols
DC Voltage SupplyAC Voltage Supply
DC Current SupplyAC Current Supply
Kirchhoff’s Current Law “The net current in a node is zero.”For example…
Kirchhoff’s Voltage Law “The sum of the voltages in any
closed loop is zero.”
Digital MultimetersMeasurement Device Circuit
Symbol
Voltage Voltmeter
Current Ammeter
Resistance Ohmeter
V
A
“Through”
“Across”
“Across”(and Not in circuit)
Appendix B: Resistor Color Codes-2 Silver-1 Gold 0 Black1 Brown2 Red3 Orange4 Yellow5 Green6 Blue7 Violet8 Gray9 White
Tolerance 5% Gold10% Silver20% No 4th band
Resistor Wattage LimitResistors will burn up if their power limit is
exceeded.
1/8 W 1/4 W 1/2 W 1 W 2 W
Resistor EquationsOhm’s Law: v = iRResistance:
ALR
Resistivity in Ohms-meters ( m)
Cross-sectional AreaIn square meters (m2)
Length inMeters (m)
Resistance inOhms ()
Resistivity of Copper0.000000017.2 Ωm
Resistivity of Water
181,800 Ωm
Concept QuestionsHow would you experimentally
determine the resistivity of pencil lead?
Example Problem 1.4Compute the resistance of a copper wire
having a diameter of 2.05 mm and a length of 10 m.
Example Problem 1.5 Determine the resistance and the current
drawn by a 1500 W heater when connected to a 120 V outlet.
In-Class ProblemsWhat is the speed of an electron in
household wiring? Assume:
Mobile electrons per cc 8.5 ×1022 electrons/cm3 (for copper, if 1 per atom)
2mm diameter wire 1A
In-Class ProblemsP1.36P1.45P1.55P1.64 P1.68
On to Chapter 2…
Today’s LabToday’s Homework
How Batteries WorkBattery Parts: Two different metals
separated by an electrolyte History: The first battery was created by
Alessandro Volta in 1800. He used zinc, silver and salt water to
make a voltaic pile.
In-Class Team ProjectUsing the kitchen and office supplies
provided, build a battery.Start with Alessandro Volta’s voltaic pile.Each recorder will record the highest
voltage for the team on the chalkboard.Voltages must be approved/seen by the
instructor.The gatekeeper will make the
measurements using a voltmeter.You have 10 minutes.
Digital Multimeters
Voltmeter, Ammeter, Ohmmeter
Let’s make it interesting…
Benjamin Franklin (January 17, 1706 – April 17, 1790) was one of the Founding Fathers of the United States. Franklin was a leading author, printer, political theorist, politician, postmaster, scientist, musician, inventor, satirist, civic activist, statesman, and diplomat. As a scientist, he was a major figure in the American Enlightenment and the history of physics for his discoveries and theories regarding electricity. He invented the lightning rod, bifocals, the Franklin stove, a carriage odometer, and the glass 'armonica‘. He facilitated many civic organizations, including a fire department and a university.
John TravoltagePhETPhysics Education Technology