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Name: _____________ Class
SCIENCE 9
UNIT D
Electrical Principles
& Technology
TS Mar 2014
S9 Unit D: Electrical Principles and Technologies
1.1 Static electricity
Atomic Theory and Electricity
•Protons (+) and neutrons (0) are found in the ____________
•Electrons (-) _______ around the nucleus
•Atoms are __________ because there is a balance between the
number of positively charged protons and negatively charged
electrons.
Three Laws of electrical charges:
1.
2.
3.
When combing your hair:
(A) Initially, there are equal numbers of protons (+) and electrons (-)
on the comb and hair. No net charge.
(B) Combing transfers electrons from the hair to the comb by
_________, resulting in a negative charge on the comb and a positive
charge on the hair.
Electrostatic charge –
An object becomes electrostatically charged by
friction, which transfers electrons between two
objects in contact.
Charge separation occurs when ____________________________
_____________________________________________________
•Static electricity happens when there is an _________________
between two objects.
•Electrical Discharge - the ___________________
from one object to another because of this imbalance.
Protons of a neutral object attract the charged
electrons of the other, and the electrons “jump” to the
neutral object. Eg.When you feel a shock when
touching metal
•Lightning - lightning is a discharge from the static electricity formed
by raindrops __________________________________________.
Van De Graaff Generators (VDGs)
•A rubber belt ___________________________, acquiring a charge
by friction and the charge is then transferred to the sphere.
•When you touch the sphere, the charge builds up
on you. Your hair stands up because the _____
charges in your hair _________.
Do Check and reflect P.278 #1-9
1.2 Current Electricity
–Electric current is a steady flow of _____________________ in
the same way that water current flows.
It is the charge that flows, and the current is defined as the
______ _____ _____________.
–The
difference between static and current electricity is that current
is the _________________flow of electrons, while static is simply
the ________ ____________ of electrons.
Amperes (A): Often called “amp” for short
–Measures the rate at which electrical current flows.
Every Electric Circuit Must Contain At Least Three Elements:
1. Energy source:
2. Conductor:
(eg. copper wire)
3. Load or form of resistance: resistance can come in many forms.
(eg.
)
There is also often a ___________ to control current flow.
Elements of a Circuit
•When a circuit is closed, ___________ leave the negative side of the
battery and will flow towards the positive side. The flow of electrons
past a fixed point is called a “___________” and is measured in
amperes or amps.
•Voltage is the force that ___________________ through the
circuit. The greater the voltage and current, the more work that a
circuit can do.
•Voltage (V): A measure of the potential difference between two
places in a circuit.
–In other words, voltage tells us how much ____________ each
charged particle carries.
– The higher the voltage, the more energy each particle has.
1.3 Electrical Safety
Coming in contact with a power transmission line can prove to be
deadly. By touching it, a ____________________ can occur, because
the electricity is trying to find a path to the ground - you can
complete the circuit, but it may be fatal.
The Dangers of Electrical Shock
High voltage power lines carry 50,000V of electricity. However,
amperage is more important to consider.
•0.001A will likely not be felt at all, 0.015A to 0.020A will cause a
painful shock and loss of muscle control (which means you will not be
able to let go of the line).
•Current as low as …
•Electrical Dangers vary, depending on the situation. When the current
can flow easily, it is more dangerous.
•Insulators (such as ____________________________) hamper the
flow of electricity, but moisture is a good conductor of electricity, so
avoid _________ when working with electricity.
Protecting Yourself from Electrical Shock
The Canadian Standards Council issues labels to identify the amount
of voltage required to operate electrical devices and the maximum
current they use.
Electrical Safety Pointers...
•Never
handle electrical devices if you are wet or near water
•Don't use devices that have a frayed or exposed power cord
•Always unplug an electrical device before disassembling it
•Don't put anything into an electrical outlet - except a proper plug for
an electrical device
•Don't overload an electrical circuit, by trying to operate to many
devices at once
•Avoid power lines
•Don't bypass safety precautions when you are in a hurry
•Pull on the plug, not the cord or wire
•Never remove the third prong from a 3 prong plug
Plugs, Fuses and Breakers
The third prong of a 3 prong plug is a ______________, connected
to the ground wire of the building, in case of a short circuit.
Fuses and circuit breakers interrupt a circuit when there is too much
_________ flowing through it.
Fuses contain a thin piece of metal, which is designed to
_________if the current is too high.
Circuit breakers, on the other hand, trip a spring
mechanism, which _______________________________
through the circuit, when there is too much current. It can
be reused over and over (provided the cause of the
increased flow is corrected).
The Dangers of Lightning
A lightning strike can have 30,000A - more than enough to kill you.
Avoid being the target of a lightning strike by staying …
•Lightning can also do a lot of damage to a building. Metal
_____________ which are connected to the ground with a
_____________________, are fixed on the roof of many buildings
to prevent damage to the building during an electrical storm.
•Do Check and Reflect P.287 #1-9
1.4 Cells and Batteries
•An electrochemical cell supplies a steady _____________.
• The electricity comes from _____________________ within the
cell.
Dry Cells - electricity-producing cells referred to dry cells are 'dry'
because the chemicals used are in a _______.
The chemical reaction in a cell releases free
electrons, which travel from the __________
terminal of the cell, through the device that
uses the electricity, and back to the _________
terminal of the cell.
Dry cells are made up of two different metals,
called ______ in an electrolyte paste.
An electrolyte is a __________________________________
because it contains chemicals that form ions.
The electrolyte reacts with the electrodes, making one electrode
positive and the other negative. These electrodes
are connected to the terminals.
Wet Cells - These are called 'wet' because the
electrolyte is a _______ (usually an acid). In a car
battery, the electrolyte is ______________ _________.
Electrons travel from the ____________ electrode (zinc) through
the device and on to the positive electrode (copper).
Rechargeable Cells
Non-rechargeable cells are called ________ cells.
The chemical reactions in a secondary cell (_______________) can
be reversed by using an external electrical source to rejuvenate the
cell.
The cheapest and most common secondary cells are Nickel Oxide and
Cadmium (Ni-Cad). The reactants are restored, but the electrodes
wear out over time.
•Batteries - _______________________ creates a battery, which is
a sealed case with only two terminals.
•Electrochemistry –
•Electrolysis:
Many industries use electrolysis to separate useful elements from
solutions.
Electroplating: Silver and Gold plating can make items
look expensive.
A thin coating is produced to cover (and often
strengthen) the material.
This is often used to protect metal from
_______________.
Other Electrochemical Applications
Anodizing and Electro-refining are other examples of
electrochemical processes
•Anodizing is a process that coats aluminum parts with a layer of
____________________, which is much harder than aluminum. It is
used in products such as screen doors, airplanes, car parts,
kitchenware and jewelry.
• Electro-refining is used to remove ________________ from metal.
•Do Check and Reflect P.294 # 1-10 And Section Review P.295 #1-11
S9 UD Section 2.1
Controlling the Flow of Electrical Current
Insulators: Electrons are ________________ to the nucleus allowing
little movement, eg.
Conductors: Electrons are free to move to the positive terminal when
a voltage source is applied. Eg.
The more charged particles (or ions) present in a ____________, the
better it conducts. Pure water will not conduct electricity. ____
water will.
Neon Signs are a circuit where electrons must flow
through a gas. Usually the gas would be an
insulator, but when current is applied the electrons
are ________ and free themselves from the
atoms. This creates a mixture of charged particles
which conducts electricity. Different gases emit
different colors of light.
Semiconductors - At high temps they act like ______________.
-At low temps they act like _______________.
Examples:
Superconductors - ________________________________ Some
metals act as superconductors at extremely _____ temperatures.
Resistance: A measure of how difficult it is for
___________________. Measured in __________. High resistance
creates …
Resistors: allow current to pass through but provides resistance,
limiting the current.
Read P. 301. How does a polygraph work?
Switches and Variable Resistors
A switch is a device that ________the flow of electrons or …
When the switch is open, there is __________, because there is a
gap in the conductor.
When the switch is closed, the switch becomes the 'gap replacement'
and __________________ of electrons to continue.
To change the electron flow gradually, a variable resistor, or
___________ is used
(eg_________________________________).
Do 2.1 Check and Reflect P. 303 # 1-3,5-9
2.2. - Modeling and Measuring Electricity
Modeling Voltage
A waterfall is used, as a model, to demonstrate voltage. Water flows
when there is a change in the gravitational potential energy
(elevation). Electricity will not flow unless there is a change in
____________ ___________ (voltage).
Modeling Resistance and Current
Flow of water in pipes is used, as a model, to demonstrate resistance.
The size of pipe determines the volume of water allowed through it.
The amount of resistance, in a circuit, determines the size of the
______________,
Ohm's Law - Georg Simon Ohm, a mathematician, proved a link
between voltage (V), current (I) and resistance (R). The unit of
resistance was named after him, the ohm.
Ohm's Law states that as long as temperature stays the same:
-the resistance of a conductor …
-the current is directly proportional to the …
V =
I=
R =
V =
I =
R =
Do 1-3 p. 307
If the temperature of a resistor changes, the resistance changes as
well (resistance is usually low when the resistor is _________, and as
the temperature increases, so does resistance).
Types of Resistors - Different resistors are used for different
applications, especially in electronics. There are many styles, sizes and
shapes. The two most common are the wire-wound and carboncomposition types.
1. Wire wound: The _____________________ the wire the higher
the resistance.
2. Carbon-composite: By varying the composition and diameter
different resistances are available.
Using Test Meters
Voltmeters measure voltage difference (voltage drop) in volts.
Ammeters measure current (rate of flow) in amperes.
Small currents are measured using galvanometers.
Multimeters can measure _____________, _______________ and
______________ in a circuit.
2.3 Analyzing and Building Electrical Circuits
Engineers and designers of electrical circuits use symbols to identify
components and connections. A drawing made with these symbols is
called a schematic or schematic diagram.
Label:
Parts of a Circuit
1. A __________ provides energy and a supply of electrons for the
circuit.
2. A ________________ provides a path for current.
3. A ______________ mechanism controls current flow, turning it on
and off, or directing it into different parts of the circuit.
4. A _________ converts electrical energy into another form of
energy.
Circuits
A circuit which is open is said to be off. Sketch:
A circuit which is closed is said to be on (the load is working) because
the current is able to flow freely. Sketch:
Circuit Analysis Example – Bulldozer. Label:
Series and Parallel: There are two basic ways in which to connect
more than two circuit components:
1. In a series circuit there is only
_____________ for the current to
flow. If there is a break in a circuit the
whole circuit cannot function. Adding
components to a series circuit increases
the total resistance in the circuit and
decreases the current. eg. lights get
__________ as you add more.
2. In parallel circuit there are
___________ pathways for the current
to flow. Components in the circuit can have
their own pathway to the current source.
A break in one section of the circuit will
____________ components in another
section of a circuit. Adding resistors in
parallel decreases the total resistance of
the circuit.
Applications of Series and Parallel Circuits
House Wiring – uses _________________ circuits.
Microcircuits are made up of transistors and resistors built on an
extremely small scale.
Microcircuits (Integrated Circuits) - transistors are used with three
layers of specially treated silicon, with the middle layer receiving a
small voltage, allowing it to control the voltage in the outer layers. This
allows the transistors to act as switches.
Do Check and Reflect p. 316, # 1-11.
S9 UD 3.1
Energy Forms and Transformations
Nature of Energy
Energy is all around you. Energy is …
It is estimated that it would take approx. 2800 h of strenuous manual
labor to produce as much energy as one average Canadian uses in one
day.
In other words: A team of ______ strong people working
__________ straight!
James Joule (1818-1889) - Studied energy. He proved
that mechanical work and electricity can produce _____
and vice-versa.
Unit of measure for energy =
There are Four Common forms of energy:
1. Chemical Energy - Energy stored in
__________ and released when chemicals
react. It is potential or stored energy in …
Eg. ______________________…bonds are
broken to release energy for your body to store and use.
2. Electric Energy - The energy of _____________________.
Electrical energy is transferred when electrons travel from place to
place
Examples: Power lines carry electricity, …
3. Mechanical Energy -Energy of ___________, the energy
possessed by an object because of its motion or its potential to move.
4. Thermal Energy - Total kinetic energy of all the particles in a
substance. The ______________________________ the more
kinetic energy it has.
Examples:
TWO CUP ANALOGY: Compare two cups holding equal
amounts of water: the one containing _______ thermal
energy will feel warmer
Energy Conversions - All forms of energy ….
Law of Conservation of Energy: Energy cannot be …
TRANSFORMATIONS OF ENERGY: What energy transformations
are taking place?
Input Energy
Device
Toaster
Chemical energy
Output energy
light
Solar Calculator
Car battery
Transformations Involving Chemical and Electrical Energy
Thermocouple: A device that converts …
Made of 2 different metals (bimetal) joined together that conduct
heat at slightly different rates. When heated the difference in
conductivity results in ..
The higher the temperature difference between
the two metals, the greater the amount of
____________________ produced. A
Thermocouple can be used as a thermometer in
extreme ______temps. or difficult to access
places.
Scientists are currently researching ways to use the Ocean’s natural
thermal energy differences to generate electricity.
(p.323)
Now do Check and Reflect P.323 #1-9
3.2 Energy Transformations Involving Electrical and Mechanical Energy
1820: The Hans Christian Oersted Demonstration
A compass needle is deflected by the magnetic field of a …
He proved that a current flowing through a wire creates a
magnetic field around the wire.
1831: Michael Faraday produces first electric motor,
proving that electromagnetic forces could produce ….
How a motor works
Types of Magnets
1. Permanent magnet- a _____________________ which remains
magnetized for a long period of time (like fridge magnets)
2. Electromagnet - a coil of ________ (usually with an iron core )
which when attached to a _____________ has magnetic effects.
Advantage: you can turn it off and on… like the ones used at car
impounds/ wreckers)
Yes, if you wrap a piece of metal in a current-carrying wire you get…an
ELECTROMAGNET!!!!
1. Wrap a piece of metal in …
2. Hook the wires up to a …
3. Reversing the wires reverses the current AND reverses
the polarity of the magnet.
A simple Electric Motor requires the interaction of a permanent
magnet and an electromagnet. Strong electromagnets are made by
winding wire into a coil around an …
How do you keep an electromagnet spinning in a magnetic field to make
the motor run? Let’s look at the St. Louis Motor…
Label the St. Louis Motor
Parts of the motor:
Armature -
Commutator - a split ring that ________ the flow of electricity for a
moment and then ______________ the flow in the coil. When the
contact is broken, so is the magnetic field
Brushes - reverse the flow of electricity through the electromagnetic
coil, make contact with commutator by …
The poles of the armature are attracted to the opposite poles of
the permanent magnet. They …
At 180˚, the contact is broken and the poles are …
The split-ring commutator breaks the flow of electricity for a
moment and then reverses the …
What does changing the polarity do?
This keeps the motor …
The armature (the rotating shaft with the coil wrapped around it)
continues to spin because of momentum, allowing the brushes to come
into contact once again with the …
The poles keep being reversed as the current flow is reversed through
the coil thus continuously …
Q: Explain the steering wheel analogy to show how the split-ring
commutator helps the armature spin continuously. (p.328)
AC or DC Current
DC =
AC =
Electrons flow …
Electrons move …
Most battery operated things use DC
Wall outlets
Transformers - Power companies generate AC power because with AC,
transformers can be used to change the amount of voltage with
minimal energy loss. Some transmission lines carry 500 000 V. This
needs to be ___________ before it can be used in your home.
Transformers: a current-carrying wire is wrapped around one side of
an iron ring called a core. This is the primary coil. A secondary coil of
wire is wrapped around the other side of the core. Current flowing
through the primary coil generates an …
1. Step-down Transformers - reduce voltage. _______ windings on
the primary coil. __________ windings on the secondary coil.
2.Step-up Transformers - increase voltage. _________ wraps
around primary coil. ________ wraps around secondary coil.
Generating Electricity
1831: Michael Faraday discovers ....
Electric current can be generated by …
Today large generators move massive coils of wire rotating between
powerful magnets to generate enough electricity to power entire
cities.
1. DC Generator - is structurally the same as a DC motor. If electricity
is passed through a DC generator, it will spin like a motor.
2. AC Generators - As the motor turns one side of the
coil moves up between the magnets and the other side
moves down. Current is induced in the coil. As the
generator continues to rotate current is induced in the
coil in the opposite direction, due to two slip rings. This
reversal of current every ½ rotation generates …
Types of Generators:
Now Do Check and Reflect P.331#1-4,7-10
Section 3.3 Measuring Energy Input and Output
A. Power:
Measured in Watts (W)
1 Watt =
Power is calculated by multiplying current x voltage
P = power in …
I = current in …
V = voltage in …
P = IV
Example: An electric stove runs on 240 V and draws 30 A of current.
How much power does it use?
V = 240 V
I = 30 A
P=?
B. Energy:
Measured in Joules (J).
E = Input power x time device operates E = Pt
E = energy in
P = power in
t = time in
Example : A 800W microwave runs for 3 minutes. How much energy
does it use?
P= 800W
t= 3min
E= ?
Kilowatt Hours
Joules are a very small unit of measure. A more common way to
measure energy is to use kilojoules or kilowatt hours. The formula for
energy remains the same, but we use KW for power and hours for time.
E= Pt
J=
KJ =
Energy Dissipation
Law of Conservation of Energy:
However, the output energy of a device is almost always less than the
input energy. Why? Some of the energy has dissipated as ________
or other forms of unusable energy (like sound).
No mechanical system is 100% percent efficient. Therefore, the
output energy will always be _________ than the input energy. This
is due to …
C. Efficiency Calculations
% efficiency =
Example: A typical gas powered SUV produces 81 KJ of useful output
energy for every 675 KJ of input energy (supplied by the fuel).
Calculate the efficiency of the SUV.
Easiest way to solve is to use a ratio
Eout = 81 J
Ein
=
675 J
Comparing Efficiencies
•Florescent lights are about ____ more efficient than incandescent
lights.
•Arc-discharge lights (streetlights) are even more efficient.
•Hybrid gasoline-electric vehicles are _____ efficient than gaspowered vehicles.
Do Check and Reflect P.338 # 1-9
3.4 Reducing the Energy Wasted by Devices
Devices that have an energy-efficient design are an important
consideration for the consumer, because these devices use less …
Energy costs money and it also affects the environment, so reducing
energy consumption is a good practice.
Limits to Efficiency
Electric heater come very close to being 100% efficient, but devices
which convert electricity to other forms can never be 100% efficient.
Some energy is lost, or dissipated in a form that is not useful output.
Friction causes thermal energy to be lost, or dissipated, in many
devices.
Increasing Efficiency
Increasing the efficiency of a device depends on its purpose.
The easiest way to increase efficiency in many devices is to reduce
friction, as much as possible.eg. …
Insulating a device from heat loss is also another practical way to
increase efficiency.
Using capacitors (formerly condensers) in electrical circuits is also
another way to increase efficiency.
•Check and Reflect P.342 #4,5,6 and Section Review P.343
S9 UD 4.1 Electrical Energy Sources and Alternatives
1. Using Heat to Generate Electricity
65% of all electric power is generated by burning fossil
fuels such as coal, oil, or natural gas. Most of the fossil
fuel used in power plants is coal.
In coal-fire generating plants, the coal is first crushed into a fine
powder. It is then blown into a combustion chamber and burned. The
heat from the burning coal boils water and superheats the resulting
steam to a high temperature and pressure. This high pressure steam
drives a large turbine.
The turbine is long shaft with many fan blades. Steam striking the
blades turns the turbine. The turbine shaft rotates large
electromagnetic coils in the generator to produce electricity. Oil or
natural gas can be burned in the combustion chamber instead of coal.
2. Nuclear fission is the splitting of the atoms of a heavy
element such as uranium. The nuclear fission takes place in a
nuclear reactor. The splitting of the atoms releases an enormous
amount of energy. This release of energy is used to produce highpressure steam that drives the turbine.
3. Geothermal energy is energy that is derived from the internal heat
of the Earth. Hot water and steam naturally come to the Earth’s
surface after being heated by hot rock within the Earth’s crust. The
steam can be channeled through pipes and used to drive turbines.
4. Biomass is biodegradable waste such as agricultural waste or
composting that can be used as an energy source for steam-driven
generators.
5. Cogeneration is the use of waste energy from another process,
such as heating or generating electricity. The process of
manufacturing glass uses very high temperature furnaces. The waste
heat from the manufacturing process can be used to produce steam to
drive a turbine to generate electricity.
6. Using Water Power to Generate Electricity - About 20% of the
world’s electricity is generated by hydro-electric power plants. These
plants capture the energy of falling water. Most hydro-electric power
plants use a dam built across a river to store water in a reservoir.
Water is directed through a channel called a penstock to a large
paddle-covered turbine. The rushing water rotates the turbine which
is connected to a generator in the same way as a steam-driven turbine.
Alternative Energy Sources
7. Moving water from ocean tides can also power turbines that run
generators.
8. Wind energy can be harnessed to turn a shaft. A number of windpowered generators can be connected together in wind farms to
produce large amounts of electrical energy.
9. Solar cells use the photovoltaic effect to produce
electricity. Today’s silicon-based solar cells are much
more efficient than the first solar cells.
Eg. calculators, switches for automatic street lights and
burglar alarms
10. Fuel cells generate electricity directly from a chemical reaction
with a fuel such as hydrogen. The hydrogen comes from sources such
as gasoline or alcohol.
Renewable and Nonrenewable Energy
•Nonrenewable resources cannot be replaced as they are used up.
Alberta’s fossil fuel resources (coal, oil, and natural gas) are
nonrenewable resources.
•Renewable resources can be renewed or replenished naturally in
relatively short periods of time. Wind energy, solar energy,
geothermal energy and biomass are renewable resources. Trees are a
renewable resource if they are managed carefully.
4.2 Electricity and the Environment
Every method of generating electricity affects the
environment. Some methods create undesirable byproducts that can have negative effects on human
health and the environment.
Air Pollution - The burning of fossil fuels results in the release into
the atmosphere of many problem-causing substances.
•Fly ash is airborne ash that is produced from burning coal. Fly ash
contains small amounts of mercury which is a poisonous metal that can
damage the nervous system.
•Some of the most harmful molecules that are released from burning
coal are sulfur dioxide (SO2(g)), nitrogen oxides (NOx(g)), and carbon
dioxide (CO2(g)).
Other Environmental Effects
•Strip-mining techniques are used when deposits of coal are near the
surface. Plants, animals, soil, and rocks are cleared away above the coal
deposits so the coal can be mined. The land can be reclaimed by
replacing the soil and plants; however the original natural environment
is usually not fully restored.
•Oil and gas wells can release poisonous gases into the environment.
Concentrations of chemicals around wells are monitored for safety.
•Steam turbines often release large amounts of warm water into
nearby lakes and rivers. Increases in water temperature can alter
freshwater ecology and can sometimes kill fish.
•Nuclear power plants, hydro-electric power plants, wind farms, the
process of making solar cells, geothermal plants, and generators that
uses tidal or wave energy all can have negative effects on the
environment. However, the green sources of energy – especially wind,
tide, and geothermal – harm the environment much less than fossil
fuels do.
Conserving Energy and Nonrenewable Resources
The main benefit of conserving energy and nonrenewable resources is
less pollution. Also, temporary shortages of resources can cause
hardship and price jumps. When fuel prices skyrocket, poorer
countries cannot afford the energy they need.
A Sustainable Future
Sustainability means using resources at a rate that can be maintained
indefinitely. Without sustainable energy use, future generations may
not be able to support themselves. Decisions made with sustainability
in mind can involve compromise – taking the bus may not be as
convenient as driving your car, however, this will conserve fuel.
4.2 Electricity and the Environment
Reference: read page 351 - 353 in Science in Action 9 text.
Generating electricity has negative effects on _____________________ and the
______________________________.
Air Pollution
What is fly ash? ________________________________________________________
______________________________________________________________________
Why is the release of this fly ash a concern? __________________________________
______________________________________________________________________
Three Major Molecules Released in the Atmosphere and their Effects
Molecule
______________________
Effect
_________________________
______________________
_________________________
______________________
_________________________
Other Environmental Effects
What are two major environmental effects? Explain their effect on the environment.
a. __________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
b. __________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
What does the term sustainability mean?
______________________________________________________________________
What does the expression "Having a sustainable future" mean to you.?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
____________________________
4.3 Electrical Technology and Society
Benefits of Electrical Technologies
Electrical technologies have improved our standard of living. Most
improvements or inventions have come as a result of a desire to
improve speed, efficiency or convenience. This has resulted in freeing
up people's time to do other things.
Drawbacks of Electrical Technologies
More technology means more resources are needed to manufacture
and operate them, making sustainability more difficult to achieve. As
technology advances, obsolete devices become waste, adding to our
problems of waste disposal. Some technologies are too expensive for
some countries to adopt, leading to isolation and exclusion.
Computers and Information
Computers have revolutionized the way we accomplish many tasks,
including writing, calculations and communications. Computers use
binary numbers (0s and 1s) to store and transmit data which has led
to the digital technology era.
Electricity and Computers
Electrical current is used in one way or another in storing or
transmitting information. Lasers, photodetectors, and electrical pulses
all enable electronic devices to complete the tasks they are made to
do.
A computer hard drive uses electrical pulses to record and transmit
information, by using an aluminum or glass disk, with a thin layer of
magnetic material that spins at up to 300km/h. The electrical pulses
are sent to an arm with read and write heads, which are magnetic coils
that magnetize spots on the spinning disk.
•Reading - magnetic spots induce current in the electromagnetic coil,
reproducing 0's and 1's in the original signal and are sent to the
computer's processor.
•Writing - electrical signals are responded to from the computer's
processor.
Electrical Transmission of Information
Electrical signals are sent from computer to computer throughout the
world, making the storage and transmission of information compact,
easy and relatively cheap. Concerns with this ease are access, privacy
and safety.
•Misleading or false information is also a problem and the ‘information
explosion’ has created other storage, handling and access problems.
Search engines help locate some of the information you may be looking
for, but they cannot access everything.
4.3 Electrical Technology and Society
Reference: read page 354 - 359 in Science in Action 9 text.
In _________________ the first ________________________to place when
________________________________invented the ___________________
Benefits of Electrical Technologies
Most ______________________ or ____________________ come from a desire for
_________________________ and _____________________________.
Drawbacks of Electrical Technologies
More ____________________ means that more ____________________ are needed
to
___________________ and ____________________ devices.
Computers and Information
__________________ have revolutionized the way we accomplish many tasks
including:
a. _______________________
b. _______________________
c. _______________________
Explain what binary numbers are.
______________________________________________________________________
______________________________________________________________________
______________
Explain how a compact disc (cd) works.
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Computer hard drives also use electricity to record and transmit information.
Electrical Transmission of Information
Why is electronic storage of information important to society?
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What is information overload?
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Various types of ________________________ were developed for the Internet to sort
through the vast amounts of information.