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Electricity by definition is electric current that is used as a power source!
This electric current is generated in a power plant, and then sent out
over a power grid to your homes, and ultimately to your power outlets.
The movement of charges such
as electrons is called current, and
this electrical current is what
powers household appliances.
Electric current generation - whether from fossil fuels,
nuclear, renewable fuels, or other sources is usually
based on the:
So simple electric generators found in power plants contain, magnets
and copper wire that when put into motion relative to one another
create the electric current that is sent out to homes.
The major problem in
electricity generation
Is where does the
Motion come from
that keeps the
copper wire and
magnets moving
relative to one
another.
In this case, wind power applies a force to the blades that turns them.
The spinning blades, spin an armature that turns the copper wire
relative to the magnetic field. As long as the blades spin, electricity
will be generated!
At home, electric current
that was generated by
generators in the power
plant is used to power
electric appliances.
The electric current,
running through the
copper wire causes
the armature to spin
which is how most
motors generate
motion.
Current Electricity
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•
•
•
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Electrons flow through a conductor
Negative to positive
Circuit = continuous loop for electrons to flow
Needs energy supply (battery)
Energy user (bulb)
CIRCUIT TYPES
The simplest type of circuit involves
electricity going around with no
“choices” (electrons don’t really
choose). This is called a Series
circuit.
The other main type of circuit has
two or more branches. This is
called a Parallel circuit.
Series circuit
• Has a single loop for electrons to travel
round
• Components are connected one after
another
• Current has to travel through all
components
• Current is the same at all points
• Voltage is shared between components
Parallel circuit
• Has two or more paths for electrons to flow
down
• Current is shared between the branches
• Voltage is the same in all branches
Open & Closed Circuits
When the circuit is open the flow
of electrons stops; when the
circuit is closed then the flow of
electrons moves throughout the
circuit.
SUMMARY
In Series
Current
Voltage
Always the same
Voltage from source =
voltage used
Voltage is shared
between power users
In Parallel
The branches share
electrons and add to the total
Voltage is the same in all
branches
Electricity
• Electricity is forced around a circuit by an
electrical force field of electrons
• Flow of electricity around a circuit is called
CURRENT (I) measured in amps (A) by an
ammeter
• Voltage (V) – Increase or decrease in the
amount of electrical energy carried by the
current, measured by voltmeter
Current (I)
Current is the flow of electrons
around a circuit
• DC = direct current like battery
– Electrons flow in one direction
• AC = Alternating current like mains
– Electron flow changes direction
Resistance
• electrical resistance - a material's opposition
to the flow of electric current
Power Grids
• Power travels from the
power plant to your
house through an
amazing system called
the power distribution
grid.
• http://science.howstuffwor
ks.com/environmental/ener
gy/power.htm
• http://www.energyquest.c
a.gov/story/chapter06.htm
l
• electricity is
generated in a power
plant
• A transformer designed to increase voltage
from primary to secondary is called a step-up
transformer.
• A transformer designed to reduce voltage
from primary to secondary is called a stepdown transformer.
• http://www.energyquest.c
a.gov/story/chapter07.htm
l
• Transformers (step
up) at the power
plant boosts the
voltage
Draw your own flow
chart for power grid
• Step-up and step-down
transformers for power
distribution purposes
can be, some units
standing as tall as a
home. This photograph
shows a substation
transformer standing
about twelve feet tall:
• smaller transformers
on the poles take that
voltage down (step
down) to usually
7,200, from the
power leaving this
substation.
Forms of Energy
• Mechanical
• Chemical
• Electrical
Forms of Energy
• Mechanical- the energy an object has from its
motion or its potential.
– a. kinetic- an object in motion
– b. potential- a result of position or ability to
perform work
Forms of Energy
• Chemical- released in a chemical reaction,
often forms heat
– Batteries
– Biomass
– Petroleum
– Natural gas
– coal
Forms of Energy
• Electrical- energy made available by the flow
of electric charge through a conductor
Electricity and Resources
Does it matter how we get
electricity?
Ways to Get Electricity
Nonrenewable
• Fossil Fuels (natural gas, coal, oil)
• Nuclear (uranium)
Renewable
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Hydroelectricity
Nuclear
Wind
Tidal
Geothermal
Solar
Fossil Fuels
Fossil Fuels
• Once used up takes MANY, MANY years
(longer than our lifetime) to replenish that’s
why we call them non-renewable
• 3 types
– Coal
– Oil
– Natural Gas
Fossil Fuels
• Fossil fuels are hydrocarbons found within
the top layer of the earth’s crust.
• Formed from the fossilized remains of dead
plants and animals by exposure to heat and
pressure in the Earth's crust over hundreds
of millions of years.
Disadvantages
• Carbon dioxide (CO2) is a "greenhouse gas,"
trapping heat in the lowest part of the earth's
atmosphere. This contributes to "global warming"
–
• Sulfur dioxide (SO2) is a
key contributor to acid
rain, primarily in the
northeast U.S.
• Nitrogen oxide
contributes to acid rain
and smog, as well as
health issues such as
lung inflammation,
immune system changes
and eye irritation.
• They use up
valuable and
limited natural
resources
• They can produce
a lot of pollutionWhen coal, natural
gas or oil are
burned, they
release gases into
the atmosphere:
Hydroelectric power
Produced by
• Using water to turn a turbine to generate
electrical
• Most hydroelectric power plants have a dam
and a reservoir.
Hydro Dam
Advantages
• Fuel is not burned so there is minimal pollution
• Water to run the power plant is provided free by
nature
• Hydropower plays a major role in reducing
greenhouse gas emissions
• Relatively low operations and maintenance costs
• The technology is reliable and proven over time
• It's renewable - rainfall renews the water in the
reservoir, so the fuel is almost always there
Disadvantages
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High investment costs
Hydrology dependent (precipitation)
In some cases, using up land and wildlife habitats
In some cases, loss or modification of fish habitat
Fish entrainment or passage restriction
In some cases, changes in reservoir and stream
water quality
• In some cases, displacement of local populations
Nuclear power
This is the energy stored in the
bonds inside atoms and molecules.
When nuclear energy is released,
it can emit radioactivity and heat
(thermal energy) as well.
Nuclear
Wind Power
Wind power is produced
by using wind
generators to harness
the kinetic energy of
wind.
Only provides less than
one percent of global
energy consumption.
Tidal Power
• Tidal energy is produced through the use of
tidal energy generators.
• These large underwater turbines are placed
in areas with high tidal movements, and are
designed to capture the kinetic motion of
the ebbing and surging of ocean tides in
order to produce electricity.
Geothermal
• Heat from the Earth
• It's clean and sustainable.
• From the shallow ground
to hot water and hot rock
found a few miles beneath
the Earth's surface, and
down even deeper to the
extremely high
temperatures of molten
rock called magma.
Solar
• Energy radiates from the sun and the light rays
can be captured with photovoltaics and
semiconductors.
• Mirrors can be used to concentrate the power,
and the sun’s heat is also a thermal source.
Solar
• Solar water heating
• Photovoltaic cells
• Solar furnace
Transferring Heat Energy
• Heat is transferred from hot to cold objects
in 3 ways
Effects of Heating
• Temperature Rise
• Expansion
• Change of State
Life Cycles
Carbon Cycle
Carbon Cycle
• In the atmosphere, carbon is attached to some oxygen in
a gas called carbon dioxide.
• Plants use carbon dioxide and sunlight to make their own
food and grow.
• The carbon becomes part of the plant. Plants that die and
are buried may turn into fossil fuels made of carbon like
coal and oil over millions of years.
• When humans burn fossil fuels, most of the carbon
quickly enters the atmosphere as carbon dioxide.
Nitrogen Cycle
• Like all living things,
your body needs
nitrogen. Your body
gets the nitrogen it
needs to grow from
food.
• Most plants get the
nitrogen they need
from soil.
• Many farmers use
fertilizers to add
nitrogen to the soil to
help plants grow
larger and faster.
• Both nitrogen fertilizers and forest fires
add huge amounts of nitrogen into the
soil and nearby lakes and rivers.
• Water full of nitrogen causes plants and
algae to grow very fast and then die all at
once when there are too many for the
environment to support.
• Carbon dioxide is a greenhouse gas and
traps heat in the atmosphere.
• Without it and other greenhouse gases,
Earth would be a frozen world.
• But humans have burned so much fuel that
there is about 30% more carbon dioxide in
the air today than there was about 150
years ago, and Earth is becoming a warmer
place.
Oxygen Cycle
Oxygen Cycle
 Plants are able to use the
energy of sunlight to convert
carbon dioxide and water into
carbohydrates (C6H12O6 -sugar)
and oxygen in a process called
photosynthesis.