EE003 Electronics Concepts Final

EE 003 Electronics, Smartphones and Mobile InternetELECTRONIC CONCEPTSBY

D R . N I S S I M A M O S

Quantities and Units

Length

Mass

Time

Electric current

Temperature

Luminous intensity

Amount of substance

Quantity Unit Symbol

Meter m

Kilogram kg

Second s

Ampere A

Kelvin K

Candela cd

Mole mol

International System of Units SI Fundamental Units

1 kg is the mass of the International prototype kilogram (39.17 mm in both

diameter and height, Platinum-Iridium alloy).

1 meter is the distance travelled by light in vacuum in 1/299792458 seconds.

Except for current, all electrical and magnetic units are derived

from the fundamental units. Current is a fundamental unit.

Current

Charge

Voltage

Resistance

Ampere A

Coulomb C

Volt V

Ohm W

Watt W

Quantity Unit Symbol

Power

These derived units are

based on fundamental

units from the meter-

kilogram-second system,

hence are called mks

units.J/s = kgm2s3

sA

W/A = kgm2s3A1

V/A = kgm2s3A2

Some Important Electrical Units

47,000,000 = 4.7 x 107 (Scientific Notation)

= 47 x 106 (Engineering Notation)

Scientific and Engineering NotationVery large and very small numbers can be represented with scientific or engineering notation.

They may also be represented with metric prefixes (next lecture topic)

0.000 027 = 2.7 x 10-5 (Scientific Notation)

= 27 x 10-6 (Engineering Notation)

0.605 = 6.05 x 10-1 (Scientific Notation)

= 605 x 10-3 (Engineering Notation)

Scientific and Engineering Notation

peta

tera

giga

mega

kilo

1015

1012

109

106

103

P

T

G

M

k

Can you

name the

prefixes

and their

meaning?

Engineering Metric Prefixes

10-3

10-6

10-9

10-12

10-15

milli

micro

nano

pico

femto

m

m

n

p

f

Can you

name the

prefixes

and their

meaning?

Engineering Metric Prefixes

Another Look! Engineering Metric Prefixes

http://htwins.net/scale2/

When converting from a larger unit to a smaller unit, move the decimal point to the right.

Remember, a smaller unit means the number must be larger.

0.47 MW = 470 kW

Larger number

Smaller unit

Metric Conversions

When converting from a smaller unit to a larger unit, move the decimal point to the left.

Remember, a larger unit means the number must be smaller.

10,000 pF = 0.01 mF

Smaller number

Larger unit

Metric Conversions

When adding or subtracting numbers with a metric prefix, convert them to the same prefix first.

10,000 W + 22 kW =

10,000 W + 22,000 W = 32,000 W

Alternatively,

10 kW + 22 kW = 32 kW

Metric Arithmetic

200 mA + 1.0 mA =

200 mA + 1,000 mA = 1,200 mA

Alternatively,

0.200 mA + 1.0 mA = 1.2 mA

Metric Arithmetic

When adding or subtracting numbers with a metric prefix, convert them to the same prefix first.

Electronic Concepts (Chapter 2)Electricity and Electronics

Atoms and Electrons

Conductors, Insulators, and Semiconductors

Voltage, Current, and Resistance

Dynamic Electricity Current Flow (of electrons)

Energy and Power

MagnetismMagnetic Fields, Electromagnetism, Electromagnetic Induction

Voltage SourcesDirect-Current (DC) and Alternating Current (AC)

Analog and Digital Signals

Electricity and ElectronicsElectricity Source of energy produced by flow or storage of electrons (sub-atomic particles with a negative charge)

Electronic Devices use components such as resistors, capacitors, diodes, transistors, etc. to process electricity for particular functions:Amplify an electrical signal

Perform calculations

Store (binary) information

Fundamental understanding of electronic devices necessitates basic understanding of atoms

Electronic ConceptsElectricity and Electronics

Atoms and Electrons




Energy and Power




AtomsAll matter is composed of atoms

Atoms are composed of protons, neutrons, and electronsProtons and neutrons are tightly bond at the core (atom nucleus), while electrons orbit around the core.

Electrical Charge: Protons (+), Neutrons (no charge), Electrons (-)

There is a force (F) between electrical charges. Like charges repel; unlike charges attract.

The force is directly proportional to charge. The force is inversely proportional to the distance between charges

Atoms ContAn element is classified as a substance (an atom) that cannot be subdivided into smaller substances.The atomic (Z) number of an element corresponds to its

number of protons

Compounds are formed when two or more elements combine to form a new substance (e.i.Water H2O and Salt NaCl)

A molecule is the smallest form of a compound, which exhibits the properties of the substance.

Iron (Z26)

Salt - NaCl

Periodic Table of Elements

Structure of AtomsAccording to the classical (Bohr) model, electrons orbit the nucleus in discrete shells

Each shell can hold a maximum number of electrons (2, 8, 18, ) and corresponds to a quantized energy level (?!)Electrons in the inner-shells are strongly bond to the atom

Electrons in the outer-shells have the most energy

Electrically balanced atoms have the same number of electrons and protons (total charge of zero)

Eclectically unbalanced atoms are called ions (either positively or negatively charged)

Hydrogen (1)

Oxygen (2,6)

Structure of Atoms

The nucleus is positively charged and has the protons and neutrons.

Electron Proton Neutron

The atomic number (Z) is the number of protons and determines the particular element.

In a neutral (balanced) atom, the number of electrons is equal to the number of protons.

Electrons are negatively charged and in discrete shells.

The Bohr atom is useful for visualizing atomic structure.

Electrons Shells and Orbits

Each discrete distance (orbit) from the nucleus corresponds to a certain energy level.

The number of electrons in each shell follows a predictable pattern according to the formula, 2x(NxN), where N is the number of the shell.

Electrons orbit the nucleus of an atom at certain distances from the nucleus.

Energy levels increase as the distance from the nucleus increases

The Valence Shell

Metals have one, two or three electrons in the valence shell.

At sufficient thermal energy, valence electrons can break away from the parent atom and become free electrons.

The Copper Atom

The outer shell is called the valence shell. Electrons in this shell are involved in chemical reactions and they account for electrical current flow in metals.

Free electrons make copper an excellent conductor and make electrical current flow possible

Body-Centered Cubic

Faced-Centered Cubic

Crystal Structure of Materials

Formation example of positively and negatively charged atoms (ions)

Formation example of molecules

The caffeine molecule structure A total of 24 atoms!NOTE: Image produced by Molecules App by Sunset Lake Software

Formation example of molecules

The molecular structure of Ketamine A total of 32 atoms!NOTE: Image produced by Molecules App by Sunset Lake Software


Atoms and Electrons




Energy and Power




Categories of Materials Conductors: are materials that readily allow current

flow [e.g. Silver (best), Copper (2nd best)]

Semiconductors: are classified below the conductors in their ability to carry current because they have fewer free electrons than do conductors [e.g. Germanium]

Insulators: are nonmetallic materials that are poor conductors of electric current [e.g. glass, porcelain, Teflon]


Atoms and Electrons




Energy and Power




VoltageVoltage (V) is responsible for establishing electrical current. It is measured in units of volts (v).

Sources of voltage include batteries, solar cells, and generators.

A Cu-Zn battery, such as you might construct in a chemistry class, is shown. This is an example of a single cell battery.

Zinc(anode)

Zn + 2e

Zn2+

ZnSO4solution

Salt bridge

Copper

(cathode)

Cu 2+ + 2e

CuSO4solution

+

e

e

e

e

A

Ammeter

Zn2+

Zn2+

SO42-

Cu2+

https://youtu.be/C26pH8kC_Wk

Batteries An automobile battery is an example of a multiple cell battery. Like all batteries, the automotive battery does not store charge it stores

chemical energy that can be converted to current when an external path is provided to allow the chemical reaction to proceed.

Battery

Rather than saying charging a battery, it is more accurate to say reversing the chemical reaction in a battery.

Ampere-hour (Ah) Rating of Batteries

Expected battery life of batteries is given as the ampere-hours specification. Various factors affect this, so it is an approximation. (Factors include rate of current withdrawal, age of battery, temperature, etc.)

How many hours can you expect to have a battery deliver 0.5 A if it is rated at 10 Ah?

10

0.5 = 20

Battery

Batteries

Electrical CurrentCurrent (I) is the amount of electrons that flows past a point

in a unit of time. It is measured in units of ampere (A).

1 A corresponds to 6,241,509,324,000,000,000 (1 Coulomb) electrons

moving through a given cross section in 1 second (s).

Illustration of 1 A of current (1 C/s) in a material.

Electrical Safety

Shock hazard in terms of three basic current path groups.

The amount of current is dependent on voltage and resistance. The human body has resistance that

depends on many factors, which include body mass, skin moisture, and points of contact of the

body with a voltage potential.

* A rough value for the internal resistance of the human body is 300-1,000 Ohms.

Voltage is the amount of energy available to move electrons from one point to another in a circuit and is measured in volts.

Current is the time rate of electron (charge) flow and ismeasured in amperes.

Resistance is the opposition to current and is measured in ohms.

Review of Voltage, Current, Resistance

ResistanceResistance (R) is the opposition to current. Components designed to have a specific amount of resistance are called resistors.

ResistanceMaterials tend to resist the flow of electricity through them.

This property is called resistance

The resistance of an object is a function of its length (l) and cross sectional area (A) and the materials resistivity:

38

lR

A

Resistivity of Common Materials

39

Voltage, Current, Resistance

Random motion of free electrons in a material

Electrons flow from negative to positive when a voltage (V) is applied across a conductive or semiconductive material

How much current (I) is flowing through the material?

Ohms Law (The Most Important Law in Electronics)

In a resistor, the voltage across a resistor is directly proportional to the current flowing through it (Ohms Law).

The higher the resistance, the less current will flow through for a given voltage.

V IR

Ohms Law (The Most Important Law in Electronics)

A Graphic Aid for Ohms Law

What is the current in a circuit with a 12 V source if the resistance is 10 W?

=

=12

10= 1.2

What is the voltage across a 680 W resistor if the current is 0.0265 A (26.5 mA)?

= = 0.0265 680 = 18.02

The DMM (Digital Multimeter) is an important multipurpose instrument which can measure voltage, current, and resistance. Many include other measurement options.

V

Hz

10 A

40 mA

OFF

mV

A

V

H

H

V H

COM

VW

Typical Digital Multimeter

http://youtu.be/bF3OyQ3HwfU

Example of an DMM Connection to Measure Current in a Simple Circuit.

Example of an DMM Connection to Measure Current in a Simple Circuit.

VR

I

115 V

V

1 s

1 s

40 mA

10 A

COM

Range

Autorange

Touch/Hold

Fused

OFF V

V

Hz

mV

A

What is the (hot) resistance of the bulb? 132 W

Example of a DMM Connection to Measure Voltage in a Simple Circuit.

Example of using a DMM to Measure Resistance of a Resistor.


Atoms and Electrons




Energy and Power


Direct-Current (DC) and Alternating Current (AC)


The Electric CircuitA basic electric circuit consists of

1) a voltage source2) a path 3) a load.

Switch Metal strip

Metal reflector Spring

An example of a basic circuit is a flashlight, which has each of these plus a control element the switch.

The Electric CircuitCircuits are described pictorially with schematics. For example, the flashlight can be represented by

Battery

Switch

Lamp

Path Path

Path Path

Current will flow through the lamp filament ONLY when there is a closed path between the + and - terminals of the battery

The Electric Circuit

Illustration of closed and open circuits using an a single switch for control

Note: Current in these examples represents the flow of negatively charged particles (the electrons)

Voltage, Current, Resistance Another look!

Voltage, Current, Resistance Another look!Ball Electron

Ball (Rotational) Motion Current (Flow of Electron)

Platform Wire (Conductor)

Platform Tilt (Angle) Voltage

Surface Roughness of Platform Resistance

Less Resistance

More Resistance

ON/OFF Switch

No Tilting = No VoltageNo Ball Motion = No Current

Tilting = Voltage AppliedBall Motion = Current Flow

Tilting = VoltageBall Motion = Current Flow


Clockwise Tilting = Positive Voltage


Counterclockwise Tilting = Negative Voltage

The Electric CircuitIllustration of closed and open circuits using a single switch for control


Atoms and Electrons




Energy and Power


Direct-Current (DC) and Alternating Current (AC)


The force must be measured in the same direction as

the distance. The unit for work is the newton-meter

(N-m) or joule (J).

When a constant force is applied to move an object over a distance, the work is the force times the distance.

Force

Distance

Energy and Power

One joule is the work done when a force of one newton is applied through a distance of one meter.

A joule is a small amount of work approximately equal to the work done in raising an apple over a distance of 1 m.

1 n

1 m

Energy and Power

Energy is closely related to work. Energy is the ability to do work. As such, it is measured in the same units as work, namely the newton-meter (N-m) or joule (J).

Power is the rate of doing work. Because it is a rate, a time unit is required. The unit is the joule per second (J/s), which defines a watt (W).

The work done to move a box from one point to another is 2000 J. What power is developed if it took 10 s to move the box?

WP

t

2000 J

10 s

WP

t 200 W

Energy and Power

The kilowatt-hour (kWh) is a much larger unit of energy than the joule. There are 3,600,000 J in a kWh! The kWh is convenient for electrical appliances.

What is the energy used in operating a 1200 W heater for 20 minutes?

1200 W = 1.2 kW

20 min = 1/3 h

1.2 kW X 1/3 h = 0.4 kWh

Energy and Power

Heater

Energy and Power

Power in Electrical DevicesVoltage alone does not equal power.

Power requires the movement of charge, i.e. a current.

Power in electrical circuits is the product of voltage and current.

VIP

In electrical devices, the rate energy is used can be determined from any of three forms of the power formula.

2P I R P VI2V

PR

Together, the three forms are called Watts law.

Power in Electrical Devices

Power in Electrical Devices

What power is dissipated by a heater that draws 12 A of current from a 120 V supply?

12 A 120 V

1440 W

P IV

The most direct solution is to substitute into P = IV.

Why Do Electronic Devices Get HOT?

2P I R


Atoms and Electrons




Energy and Power




Magnetic fields are composed of invisible lines of force that radiate from the north pole to the south pole of a permanent magnets.

Field lines can be visualized with the aid of iron filings sprinkled in a magnetic field.

The Magnetic Field

Magnetic fields are described by drawing flux lines that represent the magnetic field.

Where lines are close together, the flux density is higher.

Where lines are further apart, the flux density is lower.

The Magnetic Field

The Magnetic FieldMagnetic Attraction and Repulsion (of Permanent Magnets)

The unit of flux () is the Weber (Wb).

The unit of flux density (B) is the Tesla (T).

Flux density is given by the equationwhere

B = flux density (T)j = flux (Wb)A = area (m2)

B=j

A

Flux lines (j

Area (m)2

The Magnetic Field

Note: 1 T is relatively a large unit for magnetic fields

To measure magnetic fields, an instrument called a gaussmeter is used. A typical gaussmeter is shown.

The gauss (G) is a unit of flux density and is a much smaller

unit than the tesla (1 T = 10,000 G).

Gaussmeters are commonly used for testing motors, classifying magnets, mapping magnetic fields, and quality control by manufacturers of motors, relays, solenoids, and other magnetic devices.

The Magnetic Field

The Magnetic FieldMagnetic Materials

In ferromagnetic materials such as iron, nickel, and cobalt, magnetic domains are randomly oriented when unmagnetized.

When placed in a magnetic field, the domains become aligned, thus they effectively become like permanent magnets.

Effect of Magnetic Fields on Materials

(a) nonmagnetic (b) magnetic materials


Soft MagnetsWill align their magnetization in the direction of relatively weak magnetic fields (H)

After external field source is turned off, magnetic domains will randomize within the material and produce NO external magnetic field.

Applications: Transformers, Inductors, etc.

Hard (Permanent) MagnetsAre more resilient to influence from relatively weak magnetic fields (H)

After external field source is turned off, magnetic domains will NOT randomize and thus continuously produce a magnetic field

Applications: Motors, Generators, Clamps, etc.


In an unmagnetizedferromagnetic material, domains point in random directions.

In a magnetized ferromagnetic material, most or all of the domains point in the same direction.

Connecting the north pole of one magnet to the south pole of another magnet essentially creates one larger magnet.

The Magnetic FieldMagnetic Materials: Soft Magnets

Unmagnetized(original state)

Magnetized(by turning ON an external

magnetic fields source)

Unmagnetized(After turning OFF the external magnetic field

source)

Note: External magnetic field source can be a permanent magnet or an electromagnet

The Magnetic FieldMagnetic Materials: Hard Magnets

Unmagnetized(original state)

Magnetized(by turning ON an external

magnetic fields source)

(Still) Magnetized(After turning OFF the external

magnetic field source)

Note: External magnetic field source can be a permanent magnet or an electromagnet

Extra Credit QuestionsA permanent magnet sticks on a refrigerator door because?

A. Both are hard magnets

B. Both are soft magnets

C. One is magnetically soft while the other is magnetically hard

D. Not enough information to answer the question

A paper clip does NOT stick on a refrigerator door because?A. Both are hard magnets

B. Both are soft magnets

C. One is magnetically soft while the other is magnetically hard

D. Not enough information to answer the question

Magnetic flux lines surround a current-carrying wire.

The field lines are concentric circles.

Current-carrying wire

Iron filings

Electromagnetism

As in the case of bar magnets, the

effects of electrical current can be

visualized with iron filings around

the wire the current must be large

to see this effect.

Magnetic Quantities

Electromagnetism

The movement of electrons generates a magnetic field!

When a wire is moved across a magnetic field, there is a relative motion between the wire and the magnetic field.

When a magnetic field is moved past a stationary wire, there is also relative motion.

NS

NS

In either case, the relative motion results in an induced voltage in the wire.

Electromagnetic Induction

The induced voltage due to the relative motion between

the conductor and the magnetic field is dependent on

three factors:

The flux density

The length of the conductor in the magnetic field

The relative velocity (motion is perpendicular)


Faraday experimented with generating current by relative

motion between a magnet and a coil of wire.

The amount of voltage induced across a coil is determined

by two factors:

Faradays law

1. The rate of change of the

magnetic flux with respect

to the coil.NS

V- +Voltage is indicated only when magnet is moving.


Faraday also experimented generating current by relative motion between a

magnet and a coil of wire.

The amount of voltage induced across a coil is determined by two factors:

1. The rate of change of the

magnetic flux with respect

to the coil.

2. The number of turns of

wire in the coil.

NS

V- +

Faradays law

Voltage is induced only when magnet is moving.


Just as a moving magnetic field induces a voltage, current in a coil

causes a magnetic field.

The coil acts as an electromagnet, with a north and south pole as in the

case of a permanent magnet.

NorthSouth

Magnetic Field Around a Coil

A DC generator includes a rotating coil,

DC GeneratorMechanical drive turns the shaft

which is driven by an external mechanical force (the coil is shown as a loop in this simplified view). As the coil rotates in a magnetic field, a pulsating voltage is generated.

Brushes

Commutator

To external circuit


A dc motor converts electrical energy to mechanical motion by action of a magnetic field set up by the rotor.

DC Motor

Mechanical output

Brushes

+

I

The rotor field interacts with the stator field, producing torque, which

causes the output shaft to rotate.

The commutator serves as a mechanical switch to reverse the current to the rotor at just the right time to continue the rotation.

Commutator


Earth At Nighthttp://youtu.be/Q3YYwIsMHzw


Atoms and Electrons




Energy and Power




Alternators

Voltage SourcesDirect Current Vs. Alternating CurrentThe Hoover Dam Between the States of Arizona and NevadaApproximately Generates 4.2 Billion kWh of Energy Per Year

Voltage SourcesDirect Current Vs. Alternating CurrentNuclear Power Plant

How Nuclear Energy Works: https://youtu.be/_UwexvaCMWA, https://youtu.be/1U6Nzcv9Vws

Voltage SourcesDirect Current Vs. Alternating CurrentSolar Panels

How Solar Panels Work: https://youtu.be/1gta2ICarDw?t=45s

Voltage SourcesDirect Current Vs. Alternating CurrentSolar Thermal Energy

How Solar Thermal Works: https://youtu.be/LMWIgwvbrcM

Mojave Desert



How Solar Thermal Works: https://youtu.be/LMWIgwvbrcM Mojave Desert, CA

In a two-tank direct system, solar thermal energy is stored in a heat-transfer fluid.

The fluid is divided into two tanks: One tank storing it at a low temperature, and

The other at a high temperature

Fluid stored in the low temperature tank runs through the power plant's solar collector where it's reheated and sent to the high temperature tank.

Fluid stored at a high temperature is sent through a heat exchanger that produces steam, which is then used to produce electricity in the generator.

And once it's been through the heat exchanger, the fluid then returns to the low temperature tank


Atoms and Electrons




Energy and Power




Voltage SourcesDirect Current Vs. Alternating Current

A current that remains constant with time is called Direct Current (DC) Figure (a) Such current is represented by the

capital I, time varying current uses the lowercase, i.

A common source of DC is a battery. V IR

Higher Current Output Higher Voltage Output


A current that varies sinusoidally with time is called Alternating Current (AC) For time-varying current we designate the

lowercase, i.

A common source of AC is an alternator

N

S

Phase 1

Phase 2

Phase 3

Neutral

Note: Utility companies use 3-phase alternators and deliver all three phases to industrial customers.

In vehicles, alternators generate AC, which is converted to DC for operating electrical devices and charging the battery. A basic vehicle alternator is illustrated. AC is more efficient to produce and can be easily regulated, hence it is generated and converted toDC by diodes.

Diode plate

Rotor

Stator coils

Housing

Slip ringsDiodes

The output is taken from the rotor through the slip rings.


A wave is a disturbance. Unlike water waves, electrical

waves cannot be seen directly but they have similar

characteristics.


The sinusoidal waveform (sine wave) is the fundamental alternating current (ac) and alternating voltage waveform.

Sine waves

Electrical sine waves are named from the mathematical function with the same shape.

Sine waves are characterized by the amplitude and period. The

amplitude is the maximum value of a voltage or current; the

period is the time interval for one complete cycle.

0 V

10 V

-10 V

15 V

-15 V

-20 V

t ( s)m0 25 37.5 50.0

20 V

The amplitude (A) of this sine wave is 20 V

The period is 50.0 ms

A

T

Sine waves

The period of a sine wave can be measured between any two corresponding points on the waveform.

T T T T

T T

By contrast, the amplitude of a sine wave is only measured from the center to the maximum point.

A

Sine waves

3.0 Hz

Frequency ( f ) is the number of cycles that a sine wave completes in one second.

Frequency is measured in hertz (Hz).

If 3 cycles of a wave occur in one second, the frequency is 1.0 s

Sine waves: Frequency

The period and frequency are reciprocals of each other.

Tf

1 and

fT

1

Thus, if you know one, you can easily find the other.

If the period is 50 ms, the frequency is 0.02 MHz = 20 kHz.

Sine waves: Period and Frequency

=1

=

1

50=

1

50106=

1

50106 = 0.02106

Sinusoidal voltages are produced by ac generators and

electronic oscillators.

Sinusoidal voltage sourcesGeneration of a sine wave

N S

Motion of conductor Conductor

B

C

D

A

AB

C

D

A

BB

C

D

A

CB

C

D

A

D

When a conductor rotates in a constant magnetic field, a sinusoidal wave is generated.

When the conductor is moving parallel with the lines of flux, no voltage is induced.

When the loop is moving perpendicular to the lines of flux, the maximum voltage is induced.

B

C

D

A

Generators convert rotational energy to electrical energy. A

stationary field alternator with a rotating armature is shown. The armature has an induced voltage, which is connected through slip rings and brushes to a load. The armature loops are wound on a magnetic core (not shown for simplicity).

AC generator (alternator)

N S

slip rings

armaturebrushes

Small alternators may use a

permanent magnet as shown here;

other use field coils to produce the

magnetic flux.

AC generator (alternator)

By increasing the number of poles, the number of cycles per revolution is increased. A four-pole generator will produce two complete cycles in each revolution.

There are several ways to specify the voltage of a sinusoidal

voltage waveform. The amplitude of a sine wave is also called

the peak value, abbreviated as VP for a voltage waveform.

0 V

10 V

-10 V

15 V

-15 V

-20 V

t ( s)m0 25 37.5 50.0

20 V

The peak voltage of this waveform is 20 V.

VP

Sine waves: Voltage and Current

0 V

10 V

-10 V

15 V

-15 V

-20 V

t ( s)m0 25 37.5 50.0

20 V

The voltage of a sine wave can also be specified as either the

peak-to-peak or the rms value.

The peak-to-peak is twice the peak value.

The rms value is 0.707 times the peak value.

The peak-to-peak voltage is 40 V.

The rms voltage is 14.1 V.

VPP

Vrms

Sine waves: Voltage and Current

0 V

10 V

-10 V

15 V

-15 V

-20 V

t ( s)m0 25 37.5 50.0

20 V

For some purposes, the average value (actually the half-

wave average) is used to specify the voltage or current.

By definition, the average value is as 0.637 times the

peak value.

Sine wave voltage and current values

The average value for the sinusoidal voltage is 12.7 V.

Vavg

An important application of phase-shifted sine waves is in electrical power systems. Electrical utilities generate ac with three phases that are separated by 120 as illustrated.

Phase shift

120o

Normally, 3-phase power is delivered to the user with three hot lines plus neutral. The voltage of each phase, with respect to neutral is 120 V.

120o 120o

ac or dcsource

Bulb

The power relationships developed for DC circuits apply to AC circuits except you must use rms values in AC circuits when calculating power.

0 V

0 V

For example, the dc and the ac sources produce the same power to the bulb:

120 Vdc

170 Vp= 120 Vrms

Power in Resistive AC Circuits

rms rms

2

2

rms

rms

P V I

VP

R

P I R

Assume a sine wave with a peak value of 40 V is applied to a 100 W resistive load. What power is dissipated?

Power in resistive AC circuits

2 228.3 V

100

rmsVPR

W

Voltage (V)

40

0

30

20

10

-10

-20

-30

- 40

Vrms = 0.707 x Vp = 0.707 x 40 V = 28.3 V

8 W

Power in Resistive AC Circuits


Atoms and Electrons




Energy and Power




Digital Vs. Analog Signals

ReferencesFundamentals of Electric Circuits, 5th Edition

Authors: Charles K. Alexander & Matthew N.O. Sadiku - ISBN: 978-0-07-338057-5

Electronics Fundamentals: Circuits, Devices, and Applications, 8th Edition

Authors - Thomas L. Floyd & David M. Buchla - ISBN: 978-0-13-507327-8

http://www.tutorvista.com/content/science/science-i/structure-atom/arrangement-electrons-atom.php

http://wsc11sci.wikispaces.com/Atomic+Structure

http://www.chem.ufl.edu/~itl/2045/lectures/lec_h.html

http://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Structure/metallic_structures.htm

http://physics.gac.edu/~chuck/PRENHALL/Chapter%2031/AABXTEI0.html

http://science.howstuffworks.com/magnet1.htm

http://electronics.howstuffworks.com/everyday-tech/battery6.htm

http://www.mindspring.com/~cityzoo/mjohnson/papers/recording/images/tape.gif

http://www.powersavings.biz/images

http://djysrv.blogspot.com/2012_07_15_archive.html

http://en.wikipedia.org/wiki/Nuclear_power_plant

http://www.jakewyman.com/index.php#mi=2&pt=1&pi=10000&s=17&p=0&a=0&at=0

Example Sine Waves

Given the sinusoid show, find the following properties:

Assume the above signal is applied to a 200 resistive load. What power is dissipated?

P =2

=

7.072 2

200 = 0.25

Amplitude (A)Period (T)Frequency (f)Peak Voltage (Vp)Peak-to-Peak Voltage (Vpp)RMS Voltage (Vrms)Average Voltage (Vavg)

= 10 V= 2 s= 1/T = 0.5 Hz= 10 V= 20 V= 0.707 * Vp = 7.07 V= 0.637 * Vp = 6.37 V

Help with Prefixes

Laws of Exponents

1 =1

= +

=

1/Prefix New Prefix

1/P f

1/T p

1/G n

1/M

1/k m

1/m k

1/ M

1/n G

1/p T

1/f P

ExamplesBattery Ratings:

=10

100=? h

=10

100 = 0.1 = 100

Ohms Law

=

=

100

10=?

=100 103

10 106 = 10 109 = 10

Period/Frequency

=1

=

1

100 =?

=1

100 = 0.01 = 10

EE003 Electronics Concepts Final

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