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