Physics 110Physics 110

Fundamentals of Fundamentals of ElectronicsElectronics

Fundamentals of ElectronicsFundamentals of Electronics Student Information SheetStudent Information Sheet SyllabusSyllabus BlackboardBlackboard BooksBooks

Physics 110 LabPhysics 110 Lab

Labs start on Monday, September 12Labs start on Monday, September 12I have all labs posted in the calendarI have all labs posted in the calendar

What Can I Expect?What Can I Expect?

Lecture StyleLecture Style PowerPoint, Chalkboard, DemosPowerPoint, Chalkboard, DemosClass participation is good.Class participation is good.

ExamsExamsExams problems are much like the homework Exams problems are much like the homework

problems and in-class exercises.problems and in-class exercises.

Where do we find electrical circuits?Where do we find electrical circuits? CommunicationsCommunications

Radio, internet, telephone, televisionRadio, internet, telephone, television Data ProcessingData Processing

Desktop computers, serversDesktop computers, servers AutomobilesAutomobiles

displays, sensors, motorsdisplays, sensors, motors HomeHome

lighting, heating, applianceslighting, heating, appliances Weather StationsWeather Stations

wind speed, precipitation, temperaturewind speed, precipitation, temperature Power PlantsPower Plants

moving magnets, transformersmoving magnets, transformers

Chapter 2Chapter 2

DC NetworksDC Networks

Review TopicsReview Topics Scientific NotationScientific Notation Units of MeasureUnits of Measure

Scientific Notation and PrefixesScientific Notation and Prefixes 1,000,000,000,0001,000,000,000,000 1,000,000,0001,000,000,000 1,000,0001,000,000 1,0001,000 11 0.0010.001 0.0000010.000001 0.0000000010.000000001 0.0000000000010.000000000001

Write each number in scientific notation and give the metric prefix for each.

1012 – tera (T)

109 – giga (G)

106 – mega (M)

103 – kilo (k)

100

10-3 – milli (m)

10-6 – micro ()

10-9 – nano (n)

10-12 – pico (p)

Electrical Units SIElectrical Units SI

Derived quantity Name Symbol   Expression  in terms of  

other SI units

Expressionin terms of

SI base units

power, radiant flux watt W J/s m2·kg·s-3

electric charge, quantity of electricity coulomb C   - s·A

electric potential difference volt V W/A m2·kg·s-3·A-1

capacitance farad F C/V m-2·kg-1·s4·A2

electric resistance ohm V/A m2·kg·s-3·A-2

electric conductance siemens S A/V m-2·kg-1·s3·A2

magnetic flux weber Wb V·s m2·kg·s-2·A-1

magnetic flux density tesla T Wb/m2 kg·s-2·A-1

inductance henry H Wb/A m2·kg·s-2·A-2

Celsius temperaturedegree Celsius

°C   - K

QuestionsQuestions1.1. What is the difference between AC, DC, and What is the difference between AC, DC, and

static electricity?static electricity?2.2. Why does a Why does a Van de Graaff Generator make Van de Graaff Generator make

your hair stand up? your hair stand up? (Give a technical answer.)(Give a technical answer.)

3.3. Why do clothes sometimes stick together Why do clothes sometimes stick together after you take them out of the dryer?after you take them out of the dryer?

What is Electricity?What is Electricity? From the Greek word “elektron” that means From the Greek word “elektron” that means

“amber”“amber” There are two types of electricity:There are two types of electricity:

Static Electricity Static Electricity - no motion of free charges- no motion of free chargesCurrent Electricity Current Electricity - motion of free charges- motion of free charges

Direct Current (DC)Direct Current (DC) Alternating Current (AC)Alternating Current (AC)

2.2 Current2.2 Current CurrentCurrent is the rate of flow of charge through a is the rate of flow of charge through a

conductor.conductor.ConductorConductor

materials with free electronsmaterials with free electrons e.g. copper, aluminum, gold, most metalse.g. copper, aluminum, gold, most metals

InsulatorInsulator materials with no free electronsmaterials with no free electrons e.g. glass, plastics, ceramics, woode.g. glass, plastics, ceramics, wood

SemiconductorSemiconductor a class of materials whose electron conductivity is between a class of materials whose electron conductivity is between

that of a conductor and insulatorthat of a conductor and insulator Examples: Silicon, GermaniumExamples: Silicon, Germanium

Can Air be a Conductor?Can Air be a Conductor?

Yep!

Electrical CurrentElectrical Current

CurrentCurrent - the rate of flow of charge through - the rate of flow of charge through a conductora conductor

Conventional CurrentConventional Current Direction of flow of positive (+) chargesDirection of flow of positive (+) charges

Electron CurrentElectron Current Opposite to that of conventional currentOpposite to that of conventional current

I=Q/tI=Q/t

I = the current in Amperes (A)I = the current in Amperes (A)

Q = the amount of charge in Coulombs (C)Q = the amount of charge in Coulombs (C)

t = the time measured in seconds (s)t = the time measured in seconds (s)

The charge of an electron is 1.6 x 10The charge of an electron is 1.6 x 10 -19-19 C C

Equation for CurrentEquation for Current

Effect of Electric Currents on the BodyEffect of Electric Currents on the Body

0.001 A can be felt0.001 A can be felt 0.005 A is painful0.005 A is painful 0.010 A0.010 A causes involuntary muscle causes involuntary muscle

contractionscontractions 0.015 A causes loss of muscle control0.015 A causes loss of muscle control 0.070 A can be fatal if the current last for more 0.070 A can be fatal if the current last for more

than 1 second than 1 second

Example Problem 2.0Example Problem 2.0

How much charge will pass through a How much charge will pass through a conductor in 0.1 seconds if the current is conductor in 0.1 seconds if the current is 0.5 Amperes?0.5 Amperes?

How many electrons are required for this How many electrons are required for this much charge?much charge?

Example 2.0Example 2.0

T = 0.1 s I = 0.5 AT = 0.1 s I = 0.5 AI = Q/t, so Q = I*t = (0.5 A)*(0.1 s) = 0.05 CI = Q/t, so Q = I*t = (0.5 A)*(0.1 s) = 0.05 C

Charge/eCharge/e-- = 1.6 X 10 = 1.6 X 10-19 -19 C/eC/e--

# Charges = 0.05 C/ 1.6 X 10# Charges = 0.05 C/ 1.6 X 10-19 -19 C/eC/e--

# Charges = 3.125 X 1017 e-

Example 2.1Example 2.1

Determine the current in amperes through a Determine the current in amperes through a wire if 18.726 x 10wire if 18.726 x 101818 electrons pass through the electrons pass through the conductor in 0.02 minutes.conductor in 0.02 minutes.

18.726 x 1018 electrons, t = 0.02 min

Q = (18.726 x 1018 e-)(1.6 X 10-19 C/e-)

Q = 2.99616 C 3 C I = Q/t = 3 C/(0.02 min)(60 s/min) I = 2.4968 2.5 A

Example 2.2Example 2.2

How long will it take 120 C of charge to pass through a conductor if the current is 2 A?

I = Q/t, so t = Q/I = 120 C/2 A

t = 60 s

Example Problem 2.3 and 2.4Example Problem 2.3 and 2.4 Write the following in the most convenient

form using Table 2.1:

(a) 10,000 V

(b) 0.00001 A

(c) 0.004 seconds

(d) 520,000 Watts

(e) 0.0006 A

(f)4200 V

(g)1,200,000 V

(h)0.00004 A

(a) 104 V(b) 10-5 A(c) 4 X 10-3 s(d) 5.2 X 105 W(e) 0.6 mA(f) 4.2 kV(g) 1.2 MV

(h) 40 A

Wire Gauge?Wire Gauge?

AWG = American Wire GaugeAWG = American Wire Gauge AWG numbers indicate the size of the AWG numbers indicate the size of the

wire….but in reverse.wire….but in reverse. For example, No. 12 gauge wire has a For example, No. 12 gauge wire has a

larger diameter than a No. 14 gauge wire.larger diameter than a No. 14 gauge wire. What do we use to keep wires from What do we use to keep wires from

melting?melting?Answers: Fuses, Circuit Breakers, GFCIAnswers: Fuses, Circuit Breakers, GFCI

FusesFuses

Circuit BreakersCircuit Breakers

GFCI = Ground Fault Current Interrupter

Used in kitchens and bathroomsTrip quicker than circuit breakers

2.3 Voltage2.3 Voltage

VoltageVoltage is the measure of the potential to is the measure of the potential to move electrons.move electrons.

Sources of VoltageSources of VoltageBatteriesBatteries (DC) (DC)Wall Outlets (AC)Wall Outlets (AC)

The term The term groundground refers to a zero voltage or refers to a zero voltage or earth potential.earth potential.

Digital Multimeters (DMM)Digital Multimeters (DMM)

MeasurementMeasurement DeviceDevice Circuit SymbolCircuit Symbol

VoltageVoltage Voltmeter Voltmeter V

ACurrent Ammeter

Resistance Ohmmeter

BatteriesBatteries

A battery is a type of voltage source that converts A battery is a type of voltage source that converts chemical energy into electrical energychemical energy into electrical energy

The way cells are connected, and the type of cells, The way cells are connected, and the type of cells, determines the voltage and capacity of a batterydetermines the voltage and capacity of a battery

More on BatteriesMore on Batteries Positive (+) and Negative (-) terminalsPositive (+) and Negative (-) terminals Batteries use a chemical reaction to create Batteries use a chemical reaction to create

voltage.voltage. Construction: Two different metals and AcidConstruction: Two different metals and Acid

e.g. Copper, Zinc, and Citrus Acide.g. Copper, Zinc, and Citrus Acide.g. Lead, Lead Oxide, Sulfuric Acide.g. Lead, Lead Oxide, Sulfuric Acide.g. Nickel, Cadmium, Acid Pastee.g. Nickel, Cadmium, Acid Paste

Batteries “add” when you connect them in Batteries “add” when you connect them in series.series.

Circuit Symbol:Circuit Symbol:

V=W/QV=W/Q

V = the voltage in volts (V)V = the voltage in volts (V)

Q = the amount of charge in Coulombs (C)Q = the amount of charge in Coulombs (C)

W = the energy expended in Joules (J)W = the energy expended in Joules (J)

Equation for VoltageEquation for Voltage

Example Problem 2.7Example Problem 2.7 Determine the energy expended by a 12 V Determine the energy expended by a 12 V

battery in moving 20 x 10battery in moving 20 x 101818 electrons electrons between its terminals.between its terminals.

(a) If 8 mJ of energy is expended moving (a) If 8 mJ of energy is expended moving 200 200 C from one point in an electrical C from one point in an electrical circuit to another, what is the difference in circuit to another, what is the difference in potential between the two points?potential between the two points?

(b) How many electrons were involved in (b) How many electrons were involved in the motion of charge in part (a)?the motion of charge in part (a)?

Example Problem 2.8Example Problem 2.8

2.4 Resistance and Ohm’s Law2.4 Resistance and Ohm’s Law

ResistanceResistance it the measure of a material’s ability it the measure of a material’s ability to resist the flow of of electrons.to resist the flow of of electrons.

It is measure in Ohms (It is measure in Ohms ().). Ohm’s Law:Ohm’s Law:

V = I RV = I R

V or E = voltageV or E = voltage

I = currentI = current

R = resistanceR = resistance

ResistorsResistors

Example Problem 2.9Example Problem 2.9 Determine the voltage drop across a 2.2 kDetermine the voltage drop across a 2.2 k

resistor if the current is 8 mA.resistor if the current is 8 mA.

Example Problem 2.10Example Problem 2.10 Determine the current drawn by a toaster Determine the current drawn by a toaster

having an internal resistance of 22 having an internal resistance of 22 if the if the applied voltage is 120 V.applied voltage is 120 V.

Example Problem 2.11Example Problem 2.11 Determine the internal resistance of an Determine the internal resistance of an

alarm clock that draws 20 mA at 120 V.alarm clock that draws 20 mA at 120 V.

= resistivity of the material from tables= resistivity of the material from tables

AR

= length of the material in feet (ft)= length of the material in feet (ft)

A = area in circular mils (CM) = A = area in circular mils (CM) = area of a circle with a diameter of one mil (one thousandth of an inch)

Equation for ResistanceEquation for Resistance

Example Problem 2.12Example Problem 2.12 Determine the resistance of 100 yards of Determine the resistance of 100 yards of

copper wire having an 1/8 inch diameter.copper wire having an 1/8 inch diameter.

for copper is 10.37 circular mils/ft (I know, sigh)

L = 100 yds = 300 ft

ACM = (dmils)2 = (125mils)2 = 15,625

R = ℓℓ/A = (10.37 CM/ft)(300 ft)/15625 CM

R = 0.199

Concept QuestionsConcept Questions

How can you determine the current through How can you determine the current through a resistor if you know the voltage across it?a resistor if you know the voltage across it?I = V/R I = V/R

How can you change the resistance of a How can you change the resistance of a resistor? resistor? Change length, area, or temperatureChange length, area, or temperature

R = resistancesR = resistances

t = temperaturest = temperatures

= temperature coefficient from tables = temperature coefficient from tables

)tt(1RR 12112

Resistance depends on Resistance depends on Temperature Temperature

Example Problem 2.15Example Problem 2.15 The resistance of a copper conductor is 0.3 The resistance of a copper conductor is 0.3

at room temperature (20°C). Determine the at room temperature (20°C). Determine the resistance of the conductor at the boiling resistance of the conductor at the boiling point of water (100°C). point of water (100°C).

RR22 = R = R11[1 + [1 + 11(t(t22 – t – t11)])]

RR22 = (0.3 = (0.3 [1 + 0.00393(100°-20°)][1 + 0.00393(100°-20°)]

RR22 = 0.394 = 0.394

Four-banded Resistor

Five-banded Resistor

Resistor Color CodesResistor Color Codes0 Black1 Brown2 Red3 Orange4 Yellow5 Green6 Blue7 Violet8 Gray9 White

Tolerance Tolerance

5%5% GoldGold

10% 10% SilverSilver

Memorize this table.Calculator

Example Problem 2.17Example Problem 2.17 Determine the manufacturer’s Determine the manufacturer’s

guaranteed range of values for a guaranteed range of values for a carbon resistor with color bands carbon resistor with color bands of Blue, Gray, Black and Gold. of Blue, Gray, Black and Gold. 68 X 1068 X 1000 5% = 68 5% = 68 3.4 3.4

Example Problem 2.18Example Problem 2.18 Determine the color coding for a Determine the color coding for a

100 k100 k resistor with a 10% resistor with a 10% tolerance.tolerance.100 k100 k = 100,000 = 100,000

Band 1 (Brown) Band 2 (Black)Band 1 (Brown) Band 2 (Black) Band 3 (Yellow) Band 4 (Silver)Band 3 (Yellow) Band 4 (Silver)

0 Black1 Brown2 Red3 Orange4 Yellow5 Green6 Blue7 Violet8 Gray9 White

Tolerance Tolerance

5%5% GoldGold

10% 10% SilverSilver

Total Resistance for Resistors in SeriesTotal Resistance for Resistors in Series

21T RRR

Total Resistance for Resistors in ParallelTotal Resistance for Resistors in Parallel

21T R

1

R

1

R

1

PotentiometersPotentiometers They are They are three terminal devicesthree terminal devices with a with a

knob.knob. The knob moves a The knob moves a sliderslider which changes the which changes the

resistance between the terminals.resistance between the terminals. Circuit Symbols:Circuit Symbols:

What is the difference between E and V?What is the difference between E and V?

E is the voltage supplied by a battery.E is the voltage supplied by a battery. V is the voltage measured across a resistor.V is the voltage measured across a resistor.

2.5 Power, Energy, Efficiency2.5 Power, Energy, Efficiency

PowerPower is the measure of the rate of energy is the measure of the rate of energy conversion.conversion.

Resistors convert Resistors convert electrical energyelectrical energy into into heat energyheat energy.. Equation for Power:Equation for Power:

P = I E Power Delivered by a BatteryP = I E Power Delivered by a Battery

P = I V Power Dissipated by a ResistorP = I V Power Dissipated by a Resistor What are some other ways that we can write this What are some other ways that we can write this

equation?equation?

Power EquationsPower Equations

P = IV but V = IR P = I(IR) = I2R from Ohm’s Law I = V/R P = (V/R)V = V2/R

Example Problem 2.19Example Problem 2.19 Determine the current drawn by a 180 W Determine the current drawn by a 180 W

television set when connected to a 120 V television set when connected to a 120 V outlet.outlet. P = 180 WP = 180 W V = 120 VV = 120 V

I = P/V = 180 W/120 V = 1.5 AI = P/V = 180 W/120 V = 1.5 A

Simple Circuit ProblemSimple Circuit Problem Using circuit symbols, draw a circuit for a Using circuit symbols, draw a circuit for a

9V battery connected to a 109V battery connected to a 10 resistor. resistor. Draw and label the direction of Draw and label the direction of

conventional currentconventional current.. Now include a voltmeter in your sketch that Now include a voltmeter in your sketch that

will measure the voltage drop across the will measure the voltage drop across the resistors. What will it read?resistors. What will it read?

Include a ammeter that will measure the Include a ammeter that will measure the current through the resistor. What will it current through the resistor. What will it read?read?

Simple Circuit ProblemSimple Circuit Problem How much power does the battery deliver?How much power does the battery deliver? How much power does the resistor How much power does the resistor

dissipate?dissipate?

Example Problem 2.20Example Problem 2.20 Determine the resistance of a 1200W Determine the resistance of a 1200W

toaster that draws 10A.toaster that draws 10A.

Energy and power are related:Energy and power are related:

W = P tW = P t

W = energy in JoulesW = energy in Joules

P = power in WattsP = power in Watts

t = time in secondst = time in seconds

Example Problem 2.21Example Problem 2.21 Determine the cost of using the following appliances for the time indicated if the Determine the cost of using the following appliances for the time indicated if the

average cost is 9 cents/kWh.average cost is 9 cents/kWh.

(a) 1200W iron for 2 hours(a) 1200W iron for 2 hours(b) 160W color TV for 3 hours and 30 minutes(b) 160W color TV for 3 hours and 30 minutes(c) Six 60W bulbs for 7 hours.(c) Six 60W bulbs for 7 hours.

EfficiencyEfficiency

%100P

P

i

o

loi PPP

W746hp1

Example Problem 2.22Example Problem 2.22 Determine the efficiency of operation and Determine the efficiency of operation and

power lost in a 5hp DC motor that draws power lost in a 5hp DC motor that draws 18A as 230V.18A as 230V.

2.6 Series DC Networks2.6 Series DC Networks

Two elements are in series if they have only Two elements are in series if they have only one terminal in common that is not connected one terminal in common that is not connected to a third current carrying component.to a third current carrying component.

Total ResistanceTotal Resistance

N321T R...RRRR Current through a SeriesCurrent through a Series

TR

EI

Consider Figure 2.32.Consider Figure 2.32. E=24V, RE=24V, R11=2=2, R, R22=4=4, R, R33=6=6

What is RWhat is RTT??

What is I?What is I? What is VWhat is V11, V, V22 and V and V33??

What is PWhat is P11, P, P22, P, P33, and P, and PTT??

Kirchhoff’s Voltage LawKirchhoff’s Voltage Law

““The algebraic sum of the voltage rises and The algebraic sum of the voltage rises and drops around a closed path must be equal to drops around a closed path must be equal to zero.”zero.”

0VV dropsrises

Voltage-divider rule Voltage-divider rule ““The voltage across any resistor in a series is some The voltage across any resistor in a series is some

fraction of the battery voltage.”fraction of the battery voltage.”

T

xx R

ERV

2.7 Parallel DC Networks2.7 Parallel DC Networks

Two elements are in parallel if they have two Two elements are in parallel if they have two terminals in common.terminals in common.

Total ResistanceTotal Resistance

N321T R

1...

R

1

R

1

R

1

R

1

Source CurrentSource Current

TR

EI

Concept TestConcept Test

For resistors in For resistors in seriesseries, what is the same for , what is the same for every resistor? R, V or I?every resistor? R, V or I?

Answer: IAnswer: I

For resistors in parallel, what is the same For resistors in parallel, what is the same for every resistor? R, V or I?for every resistor? R, V or I?

Answer: VAnswer: V

Kirchhoff’s Current LawKirchhoff’s Current Law

““The sum of the current entering a junction The sum of the current entering a junction must equal to the current leaving.”must equal to the current leaving.”

leavingentering II

Example Problem 2.28Example Problem 2.28 Using Kirchhoff’s current law, determine Using Kirchhoff’s current law, determine

the currents Ithe currents I33 and I and I66 for the system of for the system of

Figure 2.42Figure 2.42

I1 = I2 + I3 I3 = I1 - I2 = 6 A – 2 A = 4 A I3 + I4 = I5 + I6 I6 = I3 + I4 - I5 = 4 A + 6 A – 1 A = 9 A

Consider Figure 2.35.Consider Figure 2.35. EE11=100V=100V

EE22=50V=50V

EE33=20V=20V

RR11=10=10 RR22=30=30 RR33=40=40

What is I?What is I? What is VWhat is V22??

Example Problem 2.25Example Problem 2.25

Find VFind V11 and V and V22 of Figure 2.36 using of Figure 2.36 using

Kirchhoff’s voltage law.Kirchhoff’s voltage law.

Voltage Sources in SeriesVoltage Sources in Series

Current-divider rule Current-divider rule ““The current through any resistor in parallel with The current through any resistor in parallel with

other resistors is some fraction of the source other resistors is some fraction of the source current.”current.”

x

Tx R

IRI

Example Problem 2.26Example Problem 2.26 Determine the following for the parallel network in Fig. 2.40.Determine the following for the parallel network in Fig. 2.40.

(a) R(a) RTT

(b) I(b) I(c) I(c) I22

(d) P(d) P33

2.8 Series-Parallel Networks2.8 Series-Parallel Networks

Solve for RT, I, I1, I2, and V1