Unit D

Electrical Principles & Technologie

s

1.1

Static Electricity

Read pg. 274-278

Remember that atoms may ionized by Remember that atoms may ionized by losing or gaining electronslosing or gaining electrons

Protons have a positive chargeProtons have a positive charge

Electrons have a negative chargeElectrons have a negative charge

Neutrons have a neutral chargeNeutrons have a neutral charge

Charged particles can either repel or Charged particles can either repel or attractattract

Review of the AtomReview of the Atom

Most objects have equal amounts of Most objects have equal amounts of positive and negative charge, so they are positive and negative charge, so they are neutralneutral

Electrical ChargeElectrical Charge

When there are more protons than When there are more protons than electrons, the object has a positive static electrons, the object has a positive static chargecharge

Electrical ChargeElectrical Charge

When there are more electrons than When there are more electrons than protons, the object has a negative static protons, the object has a negative static chargecharge

Electrical ChargeElectrical Charge

Opposite charges attract one anotherOpposite charges attract one another

Identical (like) charges repel one anotherIdentical (like) charges repel one another

Electrical ChargeElectrical Charge

Bringing a charged object near a neutral Bringing a charged object near a neutral object may cause charge separation in the object may cause charge separation in the neutral objectneutral object

Electrical ChargeElectrical Charge

Build-up of a charge on one object may Build-up of a charge on one object may cause a transfer of charge to another objectcause a transfer of charge to another object

Resulting spark is an “electrical discharge”Resulting spark is an “electrical discharge”

e.g. Van de Graaff generator, Tesla coil, zap e.g. Van de Graaff generator, Tesla coil, zap someonesomeone

Electrical DischargeElectrical Discharge

Van de Graaff generators use the friction of Van de Graaff generators use the friction of a belt being rubbed to build up a static a belt being rubbed to build up a static chargecharge

Van de Graaff Van de Graaff GeneratorGenerator

1.2 Current

Electricity

Read pg. 279-283

Static electricity not useful, because it does Static electricity not useful, because it does not flow continuouslynot flow continuously

Electric currentElectric current is a continuous flow of is a continuous flow of electronselectrons

AmpereAmpere is how we measure the rate of flow is how we measure the rate of flow of electric current (A) of electric current (A)

CurrentCurrentSlide 2 of Slide 2 of

5 5

Small devices (e.g. mp3 players, cell Small devices (e.g. mp3 players, cell phones) use very little currentphones) use very little current

Large devices (e.g. cars, generating Large devices (e.g. cars, generating stations) use a lot of currentstations) use a lot of current

Conductors allow electrical charge to move Conductors allow electrical charge to move wellwell

CurrentCurrentSlide 3 of Slide 3 of

5 5

CircuitsCircuitsSlide 4 of Slide 4 of

5 5

CircuitCircuit is the continuous path that electric is the continuous path that electric current flows throughcurrent flows through

Made of a conductor (e.g. wire), load (e.g. Made of a conductor (e.g. wire), load (e.g. bulb) and energy source (e.g. battery)bulb) and energy source (e.g. battery)

The energy that charged particles carry is The energy that charged particles carry is electrical energyelectrical energy

VoltageVoltage allows us to measure how much allows us to measure how much electrical energy each charged particle electrical energy each charged particle carries in a circuitcarries in a circuit

Voltage is the energy the electrons carry Voltage is the energy the electrons carry based on the push or pull they are feeling based on the push or pull they are feeling from some source (such as a battery)from some source (such as a battery)

Voltmeters allow us to measure voltageVoltmeters allow us to measure voltage

VoltageVoltageSlide 5 of Slide 5 of

5 5

SSectionection 1.31.3

Electrical Electrical SafetySafetyRead pg. 284-287

Power lines carry thousands of voltsPower lines carry thousands of volts

A downed power line may cause a A downed power line may cause a short circuit if a person comes in short circuit if a person comes in contact with itcontact with it

Short CircuitsShort Circuits

A A short circuitshort circuit is an unintended is an unintended path for electric current in a circuitpath for electric current in a circuit

Electric current will always take the Electric current will always take the shortest path availableshortest path available

High voltage could High voltage could burn or kill, and burn or kill, and may even stop the may even stop the heartheart

High current High current could cause loss of could cause loss of muscle control, muscle control, and/or deathand/or death

Electric Electric ShockShock

Current does not flow through Current does not flow through insulators (e.g. wood, rubber, air)insulators (e.g. wood, rubber, air)

Moist materials tend to conduct a Moist materials tend to conduct a little bitlittle bit

If insulation is damaged, shock is If insulation is damaged, shock is possiblepossible

Three-prong plugs have one prong Three-prong plugs have one prong for grounding current in case of for grounding current in case of short circuitshort circuit

Stopping Stopping CurrentCurrent

Fuses and circuit breakers interrupt Fuses and circuit breakers interrupt electric flow if there is too much electric flow if there is too much currentcurrent

Wire in a fuse melts with too much Wire in a fuse melts with too much currentcurrent

Tall buildings may be struck by Tall buildings may be struck by lightninglightning

Lightning rods safely ground the Lightning rods safely ground the electric current of a lightning strikeelectric current of a lightning strike

Fuses and Fuses and RodsRods

1.1.4 4

Cells and BatteriesCells and Batteries

Read pg. 288-294

““Dry” because the chemicals are a Dry” because the chemicals are a paste, and cell is sealedpaste, and cell is sealed

The paste is an electrolyte, a chemical The paste is an electrolyte, a chemical that forms ions to conduct electricitythat forms ions to conduct electricity

Electrolyte reacts with two different Electrolyte reacts with two different metals: electrodes that are either metals: electrodes that are either positive or negativepositive or negative

Dry CellsDry Cells Slide 2 of Slide 2 of 6 6

Wet CellsWet Cells Slide 3 of Slide 3 of 6 6

““Wet” because of a liquid electrolyte Wet” because of a liquid electrolyte that is usually an acid (e.g. Hthat is usually an acid (e.g. H22SOSO44))

Earliest cells were wet cellsEarliest cells were wet cells

Automobiles currently use wet cellsAutomobiles currently use wet cells

Acidic electrolytes reacts with one of Acidic electrolytes reacts with one of two electrodestwo electrodes

RechargeablesRechargeables Slide 4 of Slide 4 of 6 6

Known as “secondary” cellsKnown as “secondary” cells

Chemical reaction is reversible for a Chemical reaction is reversible for a rechargeable cellrechargeable cell

Store electricity from an outside source Store electricity from an outside source (e.g. wall socket)(e.g. wall socket)

BatteriesBatteries Slide 5 of Slide 5 of 6 6

When cells are linked together in When cells are linked together in a device, we refer to them as a a device, we refer to them as a “battery”“battery”

ElectrochemistElectrochemistryry

Slide 6 of Slide 6 of 6 6

Electrolysis uses electrical current to Electrolysis uses electrical current to separate molecules in a chemical separate molecules in a chemical reaction (e.g. production of Hreaction (e.g. production of H22 and O and O22 gases)gases)

Electroplating uses electrical current to Electroplating uses electrical current to deposit atoms of a metal onto an deposit atoms of a metal onto an electrode (e.g. silver plating)electrode (e.g. silver plating)

Electrorefining uses electrical current Electrorefining uses electrical current to remove impurities from a metal (e.g. to remove impurities from a metal (e.g. gold)gold)

2.1 2.1 Controlling the Flow Controlling the Flow of Electrical Currentof Electrical Current

Read pg. 296-302

For atoms of insulators, electrons stick For atoms of insulators, electrons stick close to the positively-charged nucleiclose to the positively-charged nuclei

Electrons in a conductor are free to Electrons in a conductor are free to move when energy is applied (e.g. Ag, move when energy is applied (e.g. Ag, Cu, Hg & Au)Cu, Hg & Au)

Normal conductors have resistance to Normal conductors have resistance to flowflow

SuperconductorsSuperconductors have perfect have perfect conductivity, but temperatures near to conductivity, but temperatures near to absolute zero neededabsolute zero needed

SuperconductoSuperconductorsrs

Slide 2 of Slide 2 of 5 5

Resistors allow a certain amount of Resistors allow a certain amount of current to passcurrent to pass

Resistance measures how difficult it is Resistance measures how difficult it is for electrons to flow through a material for electrons to flow through a material (ohms)(ohms)

Energy is deposited in the resistor, as Energy is deposited in the resistor, as heat or lightheat or light

Liquids may be good resistors (e.g. Liquids may be good resistors (e.g. distilled water)distilled water)

ResistorsResistors Slide 3 of Slide 3 of 5 5

Conductors are connected when a Conductors are connected when a switch is onswitch is on

If a switch is off, current will not flow If a switch is off, current will not flow because the conductors are separatebecause the conductors are separate

Switches usually insulate users from Switches usually insulate users from electric shockelectric shock

SwitchesSwitches Slide 4 of Slide 4 of 5 5

Variable resistors allow gradual Variable resistors allow gradual adjustment of electric currentadjustment of electric current

Also called rheostatsAlso called rheostats

Made of one single curved resistorMade of one single curved resistor

A dial changes the amount of the A dial changes the amount of the resistor that is usedresistor that is used

Variable Variable ResistorsResistors

Last Slide Last Slide

2.2 2.2 Modelling and Modelling and

Measuring Measuring ElectricityElectricity

Read pg. 304-310

A waterfall is a good model for looking A waterfall is a good model for looking at voltage in a circuitat voltage in a circuit

In a circuit, the power source pumps In a circuit, the power source pumps electric current up to higher electrical electric current up to higher electrical energyenergy

A waterfall flows down because gravity A waterfall flows down because gravity has given the water molecules has given the water molecules gravitational energygravitational energy

Slide 2 of Slide 2 of 6 6 Modelling Modelling

ElectricityElectricity

Water pipes are a good model for Water pipes are a good model for looking at current and resistance in a looking at current and resistance in a circuitcircuit

To drain a giant pool, a longer and To drain a giant pool, a longer and thinner pipe offers the most resistance, thinner pipe offers the most resistance, drains slowestdrains slowest

A shorter and wider pipe offers the least A shorter and wider pipe offers the least resistance, and allows for the most resistance, and allows for the most currentcurrent

Slide 3 of Slide 3 of 6 6 Modelling Modelling

ElectricityElectricity

Georg Ohm found a relationship Georg Ohm found a relationship between voltage (V), current (I) and between voltage (V), current (I) and resistance (R):resistance (R):

1) Resistance of a conductor is constant1) Resistance of a conductor is constant

2) Current is directly proportional to 2) Current is directly proportional to voltagevoltage

Increasing the voltage in a conductor Increasing the voltage in a conductor will increase current, since resistance is will increase current, since resistance is constantconstant

Flaw: temperature changes resistance!Flaw: temperature changes resistance!

Slide 4 of Slide 4 of 6 6 Ohm’s LawOhm’s Law

Example: Example: For I = 0.5 Amps & R = 2.0 For I = 0.5 Amps & R = 2.0 Ohms :Ohms :

V = (0.5 A)(2.0 V = (0.5 A)(2.0 ΩΩ) = 1.0 V) = 1.0 V

Example: For V = 1.2 Volts & R = 0.6 Ohms Example: For V = 1.2 Volts & R = 0.6 Ohms ::

I = (1.2 V) I = (1.2 V) // (0.6 (0.6 ΩΩ) = 2.0 A) = 2.0 A

Example: For V = 2.2 Volts & I = 1.1 Example: For V = 2.2 Volts & I = 1.1 Amps :Amps :

R = (2.2 V) R = (2.2 V) // (1.1 A) = 2.0 (1.1 A) = 2.0 ΩΩ

Slide 5 of Slide 5 of 6 6 Using Ohm’s LawUsing Ohm’s Law

Voltage V = I Voltage V = I xx R R Current I = V Current I = V // R R Resistance R = V Resistance R = V // I I

All test meters use a small amount of All test meters use a small amount of currentcurrent

Voltmeters measure the potential Voltmeters measure the potential difference between two points in a difference between two points in a circuitcircuit

Ammeters measure electric current in Ammeters measure electric current in any loop of a circuitany loop of a circuit

Multimeters measure voltage, current Multimeters measure voltage, current and resistance, depending on the and resistance, depending on the settingsetting

Slide 6 of Slide 6 of 6 6 Test MetersTest Meters̀

2.3 2.3 Analyzing and Analyzing and

Building Electrical Building Electrical CircuitsCircuits

Read pg. 311-315

Scientists and engineers use circuit Scientists and engineers use circuit drawings to plan and repair electrical drawings to plan and repair electrical circuits circuits

Four components:Four components:

1)1)Source provides energy and electron Source provides energy and electron flowflow

2)2)Conductor provides pathway for Conductor provides pathway for currentcurrent

3)3)Switch diverts flow or turns current Switch diverts flow or turns current on/offon/off

4)4)Load changes electrical into other Load changes electrical into other energiesenergies

STUDY BLUE TABLE ON PAGE 312STUDY BLUE TABLE ON PAGE 312

Schematic Schematic DiagramsDiagrams

Ex.Ex.

Schematic Schematic DiagramsDiagrams

A series circuit has all loads in one A series circuit has all loads in one single loop:single loop:

Electrons have only one path to followElectrons have only one path to follow

An interruption means no flow of An interruption means no flow of currentcurrent

Adding loads increases resistance of Adding loads increases resistance of circuitcircuit

Series CircuitsSeries Circuits

A parallel circuit has several loops in a A parallel circuit has several loops in a circuit:circuit:

Loads in separate loops will not Loads in separate loops will not interfere with each otherinterfere with each other

Loads in separate loops reduce total Loads in separate loops reduce total resistance of circuitresistance of circuit

Parallel CircuitsParallel Circuits

ApplicationsApplications House wiring uses parallel wiring so House wiring uses parallel wiring so

that one circuit will not affect anotherthat one circuit will not affect another

Christmas lights use parallel wiring, so Christmas lights use parallel wiring, so that one bulb burning out will not affect that one bulb burning out will not affect othersothers

MicrocircuitsMicrocircuits are microscopic circuits are microscopic circuits

TransistorsTransistors are used in tiny or advanced are used in tiny or advanced circuits and act as a switch. They are made circuits and act as a switch. They are made up of 3 layers of silicon – the middle layer up of 3 layers of silicon – the middle layer controls the current in the outer layerscontrols the current in the outer layers

3.1 3.1 Energy Forms Energy Forms

and and TransformationsTransformations

Read pg. 319-323

EnergyEnergy is the ability to do work is the ability to do work

Four forms of energy are important for Four forms of energy are important for electricity:electricity:

1)1)chemical – energy stored in chemical – energy stored in chemicalschemicals

2)2)electrical – energy of charged electrical – energy of charged particlesparticles

3)3)mechanical – energy of moving mechanical – energy of moving objectsobjects

4)4)thermal – kinetic energy of particlesthermal – kinetic energy of particles

Slide 2 of Slide 2 of 5 5 Forms of EnergyForms of Energy

Energy is stored in chemical Energy is stored in chemical bondsbonds

Energy is released or Energy is released or absorbed in chemical absorbed in chemical reactionsreactions

Molecules in food contain Molecules in food contain chemical energychemical energy

Chemical energy may be Chemical energy may be transformed into forms like transformed into forms like thermal, mechanical and thermal, mechanical and electricalelectrical

Slide 3 of Slide 3 of 5 5 Chemical EnergyChemical Energy

Slide 4 of Slide 4 of 5 5

electrical energy may transform into electrical energy may transform into another form of energy using an another form of energy using an electrical deviceelectrical device

e.g. a battery charger transforms e.g. a battery charger transforms electrical energy into chemical energy electrical energy into chemical energy in cellsin cells

chemical energy may transform into chemical energy may transform into electrical energyelectrical energy

e.g. a portable flashlight transforms e.g. a portable flashlight transforms chemical energy into electrical and chemical energy into electrical and thermal energythermal energy

ChemicalChemicalElectriElectricalcal

Electrical energy may be transformed Electrical energy may be transformed into thermal energy using an electrical into thermal energy using an electrical devicedevice

e.g. an oven or heating pad transforms e.g. an oven or heating pad transforms electrical energy into thermal energyelectrical energy into thermal energy

Thermal energy may be transformed Thermal energy may be transformed into electrical energy using a into electrical energy using a thermocouplethermocouple

A thermocouple uses two different A thermocouple uses two different conductors side by side to generate conductors side by side to generate electrical energyelectrical energy

Last Slide Last Slide ThermalThermalElectricElectricalal

• Get out page 316 (#11) and 317 #1-9 questions

3.2 3.2 Energy Energy

Transformations Transformations Involving Electrical Involving Electrical

and Mechanical and Mechanical EnergyEnergy

Read pg. 324-331

All electric motors have four parts:All electric motors have four parts:

1)1)magnets along the outsidemagnets along the outside

2)2)armature – rotating shaft of motorarmature – rotating shaft of motor

3)3)commutators – ring-like structures commutators – ring-like structures that break and reverse the flow of that break and reverse the flow of currentcurrent

4)4)brushes – conduct electricity from brushes – conduct electricity from cell or battery to the commutatorscell or battery to the commutators

Slide 2 of Slide 2 of 6 6

Electric MotorsElectric Motors

How a motor works:How a motor works:

1)1)Electric current travels from the Electric current travels from the brushes into the commutatorsbrushes into the commutators

2)2)Commutators magnetize wire coilsCommutators magnetize wire coils

3)3)Magnets push or pull the wire coilsMagnets push or pull the wire coils

4)4)Rotation of armature switches the Rotation of armature switches the position of each commutatorposition of each commutator

5)5)Cycle continues until current is Cycle continues until current is stoppedstopped

Slide 3 of Slide 3 of 6 6

Electric MotorsElectric Motors

““Direct” current (DC) flows in only one Direct” current (DC) flows in only one directiondirection

““Alternating” current (AC) flows back Alternating” current (AC) flows back and forth 60 times per secondand forth 60 times per second

Power supplies at home convert power Power supplies at home convert power from the socket (AC) into DC for some from the socket (AC) into DC for some devicesdevices

e.g. computer, stereo, tve.g. computer, stereo, tv

Slide 4 of Slide 4 of 6 6

AC / DCAC / DC

Transformers use magnetic fields to Transformers use magnetic fields to transform one voltage into anothertransform one voltage into another

Two types:Two types:

Step down – have less coils coming Step down – have less coils coming out than going in (reduce voltage)out than going in (reduce voltage)

Step up – have more coils coming Step up – have more coils coming out than going in (increase voltage)out than going in (increase voltage)

Slide 5 of Slide 5 of 6 6

TransformersTransformers

Electromagnetic inductionElectromagnetic induction is the is the generation of electricity by moving a generation of electricity by moving a conductor through a magnetic fieldconductor through a magnetic field

A DC generator is just a motor with A DC generator is just a motor with current flowing out, not incurrent flowing out, not in

An AC generator has slip rings instead An AC generator has slip rings instead of commutators: current flows out of commutators: current flows out through one slip ring and then the through one slip ring and then the other, alternatingother, alternating

Slide 6 of Slide 6 of 6 6

GeneratorsGenerators

3.3 Measuring

Energy Input and Output

Read pg. 332-338

Rate at which energy is consumed by a Rate at which energy is consumed by a devicedevice

Measured in Watts (W)Measured in Watts (W)

PowerPower = = (Current)(Current) x x (Voltage)(Voltage): : PP = = II xx VV

Example: Example: If an MP3 player operates If an MP3 player operates with a with a current ofcurrent of 5.0 A5.0 A and a and a voltage ofvoltage of 3.0 V3.0 V, calculate , calculate the the powerpower use. use.

PP = = (5.0 A)(5.0 A) xx (3.0 V)(3.0 V) = = 15 W15 W

Slide 2 of Slide 2 of 6 6

Power

Slide 3 of Slide 3 of 6 6

Energy If we know power usage and how long a If we know power usage and how long a

device runs, we can calculate energy device runs, we can calculate energy useuse

Measured in Joules (J)Measured in Joules (J)

EnergyEnergy = = (Power)(Power) x x (time)(time): : EE = = PP xx tt

Example: Example: If an MP3 player operates If an MP3 player operates with a with a power of 15 Wpower of 15 W for 2 for 2 minutesminutes, , calculate the calculate the energyenergy use. use.

EE = = (15 W)(15 W) xx (2 min) (2 min) xx (60 s/min) (60 s/min) = = 1800 J1800 J

Home energy usage is measured in Home energy usage is measured in kilowatt hourskilowatt hours

Calculated the same way: E = P Calculated the same way: E = P xx t t

Difference is units: Difference is units: kilowatts vs. wattskilowatts vs. watts

& hours vs. seconds& hours vs. seconds

Slide 4 of Slide 4 of 6 6

Kilowatt Hours

Law of Conservation of Energy tells us:Law of Conservation of Energy tells us:

1)1)Energy is neither created nor Energy is neither created nor destroyeddestroyed

2)2)Energy changes from one form to Energy changes from one form to anotheranother

Energy is lost in the form of light, heat Energy is lost in the form of light, heat and/or sound or other formsand/or sound or other forms

e.g. stove loses heat to boiling water e.g. stove loses heat to boiling water and airand air

Slide 5 of Slide 5 of 6 6

Energy Dissipation

We show energy loss with percent We show energy loss with percent efficiency:efficiency:

Last SlideLast SlideEfficiency

Percent efficiencyPercent efficiency = = x 100 % x 100 %

Joules of useful Joules of useful outputoutputJoules of input Joules of input energyenergy

Example:Example: Calculate the efficiency of Calculate the efficiency of a light a light bulb that emits 20 J of bulb that emits 20 J of light for light for every 80 J that is every 80 J that is input.input.

Percent efficiencyPercent efficiency = x 100 % = x 100 % = = 25 %25 %

20 J20 J

80 J80 J

3.3.4 4

Reducing the Reducing the Energy Energy

Wasted by Wasted by DevicesDevices

Read pg. 339-342

Electric heaters could be nearly 100% Electric heaters could be nearly 100% efficient in converting electrical to efficient in converting electrical to thermal energythermal energy

Devices that convert electricity to forms Devices that convert electricity to forms other than heat may be less than 100% other than heat may be less than 100% efficientefficient

e.g. loss through heat dispersal and e.g. loss through heat dispersal and frictionfriction

Slide 2 of Slide 2 of 4 4

Limited Efficiency

Purpose may limit improvements in Purpose may limit improvements in efficiencyefficiency

Reducing friction is a way to raise Reducing friction is a way to raise efficiencyefficiency

e.g. use of bearings and oils with e.g. use of bearings and oils with moving partsmoving parts

Reducing loss of heat to outside Reducing loss of heat to outside environment is another wayenvironment is another way

e.g. insulation prevents heat loss in an e.g. insulation prevents heat loss in an ovenoven

e.g. insulation prevents loss of cold in a e.g. insulation prevents loss of cold in a fridgefridge

Slide 3 of Slide 3 of 44

Increasing Efficiency

Government and other organizations Government and other organizations have incentives and initiatives for have incentives and initiatives for increasing energy efficiency at home increasing energy efficiency at home and in businesses:and in businesses:http://oee.nrcan.gc.ca/corporate/incentives.cfm?attr=0

http://www.energy.gov.on.ca/index.cfm?fuseaction=conservation.tips

http://www.climatechange.gc.ca/onetonne/english/

http://incentivesandrebates.ca/gc_fi_search.asp

http://www.bchydro.com/powersmart/reno/reno8621.html

http://www.atcoenergysense.com/

http://www.energysolutionsalberta.com/default.asp?V_DOC_ID=1040

Last Slide Last Slide Alternatives

4.1 4.1 Electrical Electrical Energy Energy

Sources and Sources and AlternativesAlternatives

Read pg. 344-350

Approximately 60-70% of world energy Approximately 60-70% of world energy comes from fossil fuels: oil, coal and comes from fossil fuels: oil, coal and natural gasnatural gas

Fossil fuelsFossil fuels were formed when plants were formed when plants and animals decomposed during and animals decomposed during prehistoric timesprehistoric times

Some power plants are fueled by coalSome power plants are fueled by coal

Coal and nuclear power plants heat Coal and nuclear power plants heat water into steam that may drive water into steam that may drive turbinesturbines

Slide 2 of Slide 2 of 6 6

Coal Energy

A A turbineturbine is a long shaft with blades is a long shaft with blades that is propelled by steam or waterthat is propelled by steam or water

Each turbine rotates wire coils in a Each turbine rotates wire coils in a generator to produce electricitygenerator to produce electricity

Hydroelectric dams use the pressure of Hydroelectric dams use the pressure of falling water to propel turbinesfalling water to propel turbines

Geothermal energy – heat from the Geothermal energy – heat from the beneath the crust heats steam that beneath the crust heats steam that drives turbinesdrives turbines

Slide 3 of Slide 3 of 6 6

Turbine Generators

Tidal energy – moving water (tides) Tidal energy – moving water (tides) along the ocean floor propels turbine along the ocean floor propels turbine generatorsgenerators

e.g. Bay of Fundy, Nova Scotiae.g. Bay of Fundy, Nova Scotia

Wind energy – moving air (wind) along Wind energy – moving air (wind) along the ground propels turbine generatorsthe ground propels turbine generators

e.g. wind farms in the Netherlandse.g. wind farms in the Netherlands

Slide 4 of Slide 4 of 6 6

Tides & Wind Farms

Solar energy – sunlight is converted into Solar energy – sunlight is converted into electric current by silicon-based solar electric current by silicon-based solar cellscells

e.g. International Space Statione.g. International Space Station

Fuel cells – chemicals continuously feed Fuel cells – chemicals continuously feed a chemical reaction that produces a chemical reaction that produces electricityelectricity

e.g. hydrogen + oxygen e.g. hydrogen + oxygen water + water + electricityelectricity

Slide 5 of Slide 5 of 6 6

Sunlight & Fuel Cells

Renewable resources may be replaced Renewable resources may be replaced naturally after a whilenaturally after a while

e.g. light, biomass, and geothermal heate.g. light, biomass, and geothermal heat

Non-renewable resources cannot be Non-renewable resources cannot be replaced or replenished if they are used replaced or replenished if they are used upup

e.g. coal, crude oil, and natural gase.g. coal, crude oil, and natural gas

Last SlideLast SlideRenewable or Not?

4.2 4.2

Electricity and Electricity and the the

EnvironmentEnvironment

Read pg. 351-353

Burning of fossil fuels results in Burning of fossil fuels results in pollutantspollutants

Coal power plants create airborne fly Coal power plants create airborne fly ash, which contains deadly mercuryash, which contains deadly mercury

Coal is now cleaned; fly ash is now Coal is now cleaned; fly ash is now capturedcaptured

SOSO22, NO, NOxx, CO, CO22 released during coal released during coal combustion causes acid raincombustion causes acid rain

COCO22 also causes enhanced greenhouse also causes enhanced greenhouse effecteffect

Slide 2 of Slide 2 of 6 6

Air Pollution

Strip-mining of coal may harm the Strip-mining of coal may harm the natural environmentnatural environment

Oil and gas wells may release deadly Oil and gas wells may release deadly gasesgases

Steam turbines releases warm water Steam turbines releases warm water into rivers and lakes; may harm into rivers and lakes; may harm organismsorganisms

Nuclear reactors produce radioactive Nuclear reactors produce radioactive wasteswastes

Slide 3 of Slide 3 of 6 6

Environmental Effect

Hydro-electric dams flood river valleysHydro-electric dams flood river valleys

Wind farms make large areas of land Wind farms make large areas of land not useable for other purposesnot useable for other purposes

Building solar cells makes harmful Building solar cells makes harmful chemicalschemicals

Tidal generators displace marine Tidal generators displace marine organismsorganisms

Overall: alternatives harm the Overall: alternatives harm the environment far less than traditional environment far less than traditional sources of energysources of energy

Slide 4 of Slide 4 of 6 6

Environmental Effect

Higher demand for energy means Higher demand for energy means higher consumption of energy resourceshigher consumption of energy resources

Lowering your energy use means you Lowering your energy use means you are making non-renewable resources are making non-renewable resources last longerlast longer

More alternatives mean that non-More alternatives mean that non-renewable resources will last longer.renewable resources will last longer.

Slide 5 of Slide 5 of 6 6

Conservation

Sustainable energy use means making Sustainable energy use means making an energy resource last for a really long an energy resource last for a really long timetime

Personal decisions influence Personal decisions influence sustainabilitysustainability

We need to conserve our resources in We need to conserve our resources in order to sustain them over a long period order to sustain them over a long period of time.of time.

Last Slide Last Slide Sustainability

4.4.3 3 Electrical Electrical

TechnologTechnology and y and

SocietySociety

Read pg. 354-358

Electronic devices allow us to complete Electronic devices allow us to complete more tasks quickly and efficientlymore tasks quickly and efficiently

Free time may be used for other Free time may be used for other pursuitspursuits

Slide 2 of Slide 2 of 5 5

Benefits

Technology can be too expensiveTechnology can be too expensive

Resources are needed to build Resources are needed to build technologytechnology

Sustainability is threatenedSustainability is threatened

Old discarded technology creates Old discarded technology creates wastewaste

Slide 3 of Slide 3 of 55

Drawbacks

We exist in the computer ageWe exist in the computer age

Computers speak in binary numbers Computers speak in binary numbers (ones and zeroes)(ones and zeroes)

Different technologies store and Different technologies store and transmit computer information (CD’s, transmit computer information (CD’s, hard drives, etc.)hard drives, etc.)

Computers Slide 4 of Slide 4 of 55

““Hackers” break into computer Hackers” break into computer systemssystems

Misleading or “wrong” information on Misleading or “wrong” information on the internetthe internet

People feel bombarded by the People feel bombarded by the information availableinformation available

Computer virusesComputer viruses

Last SlideLast SlideInformation