Bellwork

1. Give an example for:◦ Newton’s 1st law of motion◦ Newton’s 2nd law of motion◦ Newton’s 3rd law of motion

Think about what it would have been like to live before we had electricity…

Write 2 paragraphs about how you would have made it day to day without electricity.◦ How would you have gotten ready for school?◦ How would you have made dinner?◦ How would you have survived the summers

without air conditioner?◦ How would you have survived the winters without

heat?

Read your electricity paragraph to your

neighbor

Electrical Energy2.d. Relate how electrical energy transfers through

electric circuits, generators, and power grids, including the importance of contributions from Mississippi

companies.

Today we will explore electrical energy….

Better known as ELECTRICITY

Electrical power is a little bit like the air you breathe.

You don’t really think about it until it is missing

Power is just “there” meeting your every need constantly

It's only during a power failure, when you walk into a dark room and instinctively hit the useless light switch, that you realize how important power is in your daily life

Electricity

You use electricity for heating, cooling, cooking, refrigeration, light, sound, computation, entertainment, and many other things

Without power, life would be very difficult

Think about what it was like before we had power….

Electricity

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

So what exactly is electricity?

Electric current is the movement of electron charges

This current is what powers your appliances at home

What is ELECTRIC CURRENT?

Power travels from the power plant to your house through an amazing system called a power grid

You all have probably seen a power grid before.

In fact, you have probably seen a power grid so many times that you don’t even notice it anymore

Your brain likely ignores all of the power lines too because it has seen them so often

Where does it all start?

Electrical power starts at the power plant.

In almost all cases, the power plant has an electrical generator to power it.

An electrical generator is a device that transforms mechanical energy into electrical energy.

An electrical generator spins allowing energy to pass through it

There are many things that can turn a generator:◦ Fossil fuels◦ Nuclear fuels◦ Renewable fuels◦Steam turbines◦ Water wheel◦ Diesel engine◦ Gas turbine

What causes a generator to spin?

Electric motors transform electric energy into mechanical energy

Electric motors are found in industrial fans, machine tools, household appliances, power tools, disk drives, and many other things

Electric Motors

Electric current that was produced by the generator at the power plant is sent through the power lines to your home.

This electric current is used to power your appliances at home.

When you turn on an appliance the electric current passes through the wires causing the electric motor spin.

How does it get to your home?

Electric current must be transmitted at high voltages to avoid excessive resistance

By transmitting electric current at high voltages, transmitting becomes easier

So, what is a limiting factor in the transmission of electric current in power grids?

The electric current must be transmitted at high voltages to avoid excessive resistance making transmission easier

Other information to know:

1. AC Current◦ Alternating Current –

the electrical current changes direction; changes magnitude and direction with time The current can be

easily transformed to higher or lower voltages

More suitable for long-distance transmission

Electrical power is delivered to businesses and residences through AC Current (alternating current)

Why is AC Current called alternating current?

Types of currents:

2. DC Current◦ Direct Current – the

unidirectional flow of electrical charge

Direct current is produced by sources such as batteries

Types of Currents Cont’d:

With your neighbor, discuss resources that we use for energy

Are these resources harmful or beneficial? Why?

What are some ways these resources harm our environment?

What are some ways they are beneficial to our environment?

What can we do to improve our impact on our environment?

How are we affecting our environment?

OUR ATMOSPHERE4.d. Research the importance of the conservation of renewable

and nonrenewable resources, including (but not limited to) Mississippi, and justify methods that might be useful in decreasing

the human impact on global warming. (DOK 3)

1. Weather – the condition of Earth’s atmosphere at a particular time and place

2. Atmosphere – the envelope of gases that surrounds the planet

3. Ozone – a form of oxygen that has 3 oxygen atoms in each molecule instead of the usual 2

4. Water vapor – water in the form of a gas

Words you will need to know:

Earth’s atmosphere is made up of N2, O2, CO2, water vapor, and many other gases, as well as particles of liquids and solids

Conditions of the Atmosphere

The most abundant gas in the atmosphere

Makes up a little more than ¾ of the air we breathe

Nitrogen

2nd most abundant gas in the atmosphere

Makes up less than ¼ of the volume

Plants and animals take O2 directly from the air and use it to release energy from their food

Oxygen is also involved in other important processes◦ Any fuel you can

think of (gasoline in cars, candles, etc)

◦ Anything that burns uses oxygen rapidly

◦ Slower processes such as rusting

Oxygen

Essential to life Plants must have

CO2 to produce food

When animals break down food to produce energy, they give off CO2 as a waste product

When fuels such as coal and gasoline are burned, they release CO2

Burning these fuels increases the amount of carbon dioxide in the atmosphere

Carbon Dioxide

O2 and N2 together make up 99% of dry air

Argon and CO2 make up most of the other 1%

The remaining gases are called trace gases because only small amounts of them are present

Other Gases

So far, we have discussed the composition of dry air.

In reality, air isn’t dry because it contains water vapor

Water in the form of a gas

Invisible Not the same thing

as steam The amount of

water vapor in the air varies greatly from place to place and from time to time

Plays an important role in Earth’s weather◦ Clouds form when

water vapor condenses out of the air to form tiny droplets of liquid water or crystals of ice

◦ If these droplets or crystals become heavy enough, they can fall as rain or snow

Water Vapor

Pure air contains only gases, but pure air exists only in labs

In the real world, air also contains tiny solid and liquid particles of dust, smoke, salt, and other chemicals

You can see some of these particles in the air around you, but most of them are too small to see

Particles

Earth’s atmosphere makes conditions on Earth suitable for living things◦ contains gases we need

to survive In turn, living things

affect the atmosphere Constantly changing

with gases moving in and out of living things, the land and the water

Living things need warmth and liquid water

By trapping energy from the sun, the atmosphere keeps most of Earth’s surface warm enough for water to exist as a liquid

Earth’s atmosphere protects living things from dangerous radiation from the sun

Also prevents surface from being hit by most meteoroids from or rocks from outer space

Importance of the Atmosphere

Located in the second layer of the atmosphere

This second layer is called the stratosphere

Absorbs energy from the sun, the energy is converted into hear, warming the air

Important because it protects Earth’s living things from dangerous ultraviolet radiation from the sun◦ UV rays – an

invisible form of energy with wavelengths that are shorter than violet light

◦ UV rays can cause sunburns, skin cancer, and eye damage

The Ozone Layer

Our Effect on the Atmosphere and Our

Environment

Ozone close to Earth’s surface in the form of smog is harmful

Ozone higher in the atmosphere, where people cannot breathe it, protects us

The Thinning of the Ozone Layer

Ozone is constantly being made and destroyed

In the late 1970s, scientists observed that the ozone layer over Antarctica was growing thinner each spring

The amount of ozone in the ozone layer was decreasing, causing an area of severe ozone depletion, or an ozone hole

Pg. 664-665 Scientists determined

that the major cause of the hole is a group of gases called CFC’s, which were used in many household products

The Ozone Hole

Chlorofluorocarbons are human-made gases that contain chlorine, fluorine, and carbon

They have been used in air conditioners, aerosol spray cans, and other products

CFCs react with ozone molecules and block the cycle in which ozone molecules absorb UV rays◦ As a result UV rays

reach Earth’s surface

CFCs

Most uses of CFCs have been banned

Scientists began to search for new ways to make products without using CFCs

As a result, far fewer CFCs now enter the atmosphere

If the ban on CFCs is maintained, scientists predict that the ozone hole will eventually recover

What’s being done about CFCs?

GLOBAL CLIMATE CHANGE

Some changes to the climate could affect the whole planet

Think about the sun shinning through a window on a cool day. The window lets light enter the room. The light strikes objects in the room and is converted to heat. The closed windows then trap the warm air inside, and the room becomes warmer

The Greenhouse Effect

In the atmosphere, water vapor, CO2, and other gases act like a window. They allow sunlight to reach Earth’s surface, but prevent some of the heat from escaping into space

The trapping of heat near the Earth’s surface is called the greenhouse effect.

Without the greenhouse effect, Earth would be much colder – about 33 degrees C colder◦ All of Earth’s water would be frozen!

BUT… can you think of problems that the greenhouse effect might cause?

Since the 1800s, coal and oil have been the main sources of energy in many parts of the world

◦ What does burning these substances product?

Global Warming

CO2

As a result, the amount of carbon dioxide in the atmosphere has increased from 280 parts per million to 385 parts per million

This amount is increasing more quickly every year

Human activities that increase CO2 levels may be intensifying the greenhouse effect

Global warming predicts that the increase in CO2 levels will cause the average temperature to continue to rise

What are human activities that increase CO2 levels?

Think about it….

1. Is the greenhouse effect harmful? Why?2. How is the greenhouse effect related to

global warming?3. Do scientists know for certain that burning

coal and oil is causing global warming?4. How could rising sea levels and warmer

temperatures affect where people live?5. Answer questions 1-2 on page 667When you finish, turn your paper into

your class period slot on the front table

*After you turn in your work, read through chapter 20 and list fossil fuels, renewable resources, and nonrenewable resources

Answer these questions…

1. Get with your partner from yesterday and finish page 667 1-2.

2. You have 5 minutes after the bell rings to turn in your work.

3. Turn to Chapter 20 and make a list of fossil fuels, renewable resources, and nonrenewable resources.

4. This will need to be turned in 15 minutes after the bell rings

Bellwork:

Biological controls: the use of natural enemies to reduce the damage caused by a pest population.

Human exploitation: killing of animals for money or personal gain.

Nitrogen cycle: 1. Decomposers are

the first to release nitrogen

2. Animals best receive nitrogen needed by eating other plants and animals

Water cycle:1. Sunlight is the

water cycles main energy source

Other information you will need to know for your test:

Complete your study guide!

We will go over the answers the last 5 minutes of class.