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 suchas 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

• 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 In Parallel

Current

Voltage

Always the same The branches share electrons and add to the total

Voltage from source = voltage used

Voltage is shared between power users

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 electronsaround 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.howstuffworks.com/environmental/energy/power.htm

• http://www.energyquest.ca.gov/story/chapter06.html

• 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 step-down transformer.

• http://www.energyquest.ca.gov/story/chapter07.html

• 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 ElectricityNonrenewable•Fossil Fuels (natural gas, coal, oil)•Nuclear (uranium)

Renewable•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 pollution-When 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• 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.