Energy Nuclear Fusion, Nuclear Fission, Combustion and Solar Radiation

Nuclear Fusion: Energy from the Sun When two or more lighter atoms fuse together to create one larger one Occurs in all stars What are stars made of? – Hydrogen – Helium Not radioactive in nature – if processes is triggered to happen it will be radioactive

What is radioactivity? Radioactive- an element that leaks energy because the nuclei is unstable Many different isotopes (types) Most common forms are alpha, bet and gamma Used medically to treat cancer = radiation

Nuclear Fusion Must have high density, high temperature Produces 3-4x the energy that nuclear fission produces Hydrogen bomb uses nuclear fusion – first used in 1950’s as a result of the Cold War

Nuclear Fusion: Hydrogen Bomb

Brain Break What is nuclear fusion? What does it mean if something is radioactive? What things in nature does it power? What has man used nuclear fusion for?

Nuclear Fission The splitting of a large atom into two or more smaller ones Does not normally occur in nature Is mostly radioactive Must have critical mass of the substance and high speed neutrons Takes little energy

Energy released is 1 million x of that of a chemical reaction – Still less than that of nuclear fusion Used as a nuclear weapon : the atom bomb, atomic bomb Used in nuclear power plants

Combustion Combustion is a chemical process -substance reacts rapidly with oxygen and gives off heat. -the original substance is called the fuel - fuel can be liquid, gas or solid -the source of oxygen is called the oxidizer -usually air

How Combustion Works

Burning Around You Come up with and write down three of your own combustibles What is your fuel? (You need three different ones) What is your oxidizer?

3 Types of Energy List out the three types of energy and summarize their main points 1.Nuclear Fusion Nuclear Fission Combustion

How does the Earth get power? Earth receives radiation from the sun Radiation (in this sense) means all forms of energy that travels through space as waves ex. light

Types of Radiation The types of radiation are determined by the length of their waves Short wave lengths (shorter than light waves): – Ultraviolet rays – X rays – Gamma rays

Types of Radiation Longer Wavelengths include: – Infrared – Radio waves **All of these types of radiation are called electromagnetic waves

Energy and Earth Most of the energy reaching Earth passes through the atmosphere as electromagnetic waves Small amount comes through as atomic particles from the Sun

Energy and Earth’s Atmosphere 1 st the upper atmosphere (oxygen and nitrogen) absorbs the short wavelengths of x rays, gamma rays and ultraviolet rays – Occurs in thermosphere and mesosphere 2 nd in the stratosphere ultraviolet rays are absorbed and react with oxygen to form ozone 3 rd some ultraviolet radiation reaches Earth and can cause sunburn

Energy and Earth Most solar rays that reach earth have a longer wavelength (visible and infrared rays) Infrared radiation are absorbed by carbon dioxide, water vapor etc. in the troposphere We receive most visible light rays

Scattering of Energy Water drops and dust in atmosphere bend and reflect rays Causes rays to scatter On cloudless days it is caused by rays hitting gas molecules Why sunlight hits earth’s surface from all directions

Totals of Solar Energy ~ 20 % of energy is absorbed by the atmosphere ~30% is scattered back to space ~50% is absorbed by Earth’s surface – Depends on what type of surface the ray hits (water, desert, grass, snow etc.)

Sun’s Energy Heating Earth Remember season’s caused by ____________? The Earth heats differently because of the curve of the Earth Average temperatures are higher at the equator because of the Sun’s rays hitting directly on that spot

Sun’s rays have to slant to hit the poles

Sun’s Energy and Heating Earth Elevation on land plays another big role, whether like mountaintops vs. beach Even bigger difference is heating water vs. heating land Heating water – Less temperature fluctuation – Water moderates temperatures – Land near big bodies of water have more moderate temperatures

Sun’s Energy Heating Earth Heating water – Less temperature fluctuation – Water moderates temperatures – Land near big bodies of water have more moderate temperatures – Water cooler during the day – Warmer at night

Sun’s Heating Earth Heating Land – It takes a long time for land to recover from freezing in winter – Usually July before the ground has absorbed enough heat to heat up the atmosphere – Only when the ground is warm enough do the warmest summer days occur

Energy for Plants from the Sun How do plants get energy from the sun? Plants use sunlight to create food Called photosynthesis