Energy and Electricity.Physics (unit 1)This presentation will cover:•Energy•Renewable and non renewable energy•Geothermal energy•How energy is produced•National grid•Step up and step down transformer•Properties of waves: reflection, refraction and diffraction• law of reflection•Energy transfer (conduction, convection and radiation)•Transverse and longitudinal waves.•Electro magnetic spectrum•The big bang theory and the Doppler effect
So why energy?Energy is very important in todays world.For example, we use different energysources to generate the electricity weneed for our homes, schools, businessesand factories. Electricity powers our TVs,computers, air conditioners, cell phonesand washing machines - just to mentiona few. We also use energy to run cars,planes, trains, buses and motorcycles.
Different types of energy!There are different types of energy such as:Geothermal, hydroelectric, solar, wind, tidal.
There are 2 types of energy resource:RENEWABLEANDNON-RENEWABLE
Lets look at RENEWABLE:• List of renewable resources:GeothermalSolarWindTidalHydroelectricBio-energyHydrogen
Renewable energy• Renewable energy is the energy that neverrun out, we can use it over again and again.
GEOTHERMAL ENERGY• GEOTHERMAL ENERGY is the energy from hotradioactive rocks under ground.
How do we make electricity fromrenewable energy?• First, water is pumped to deep under ground,the water then heated due to hot radioactiverocks under ground.Cold water pumpeddown from a powerstation
When the water is heated at a high pressure theit produces hot steam which is then pumpedback to the power station. This hot steamturns the turbine which then turns thegenerator to produce electricity.Hot steam is thenpumped back to thegeothermal powerstation.
NON-RENEWABLE ENERGYNon renewable energy is the energy fromfossil fuels (which was found from theremaining of dead plants and animals).Non renewable will run out over time.The non renewable energy are:• Coal• Oil• And natural gas.
How is natural gas used to generateelectricity?It pretty much works in the same way asgeothermal (except to heat water from underground).1) Gas is used to boil water to produce steam.2) the steam then turns the turbine3) the turbine then turns the generator.4) the generator produce electricity.
The National grid!Electricity is distributed from powerstations to consumers through theNational Grid, which allows distantpower stations to be used. It also allowsa mix of different energy resources to beused efficiently to supply the country’selectricity, whatever the local demand.
Step up and step down transformerElectricity is transferred from power stations to consumersthrough the wires and cables of the National Grid. Currentflows through a wire; (some energy is lost as heat). Thehigher the current, the more heat is lost. To reduce theselosses, the National Grid transmits electricity at a lowcurrent. This needs a high voltage. Transformers are used inthe National Grid. A transformer is an electrical device thatchanges the voltage of an alternating current supply, suchas the mains electrical supply.A transformer that: increases the voltage is called a step-up transformer decreases the voltage is called a step-down transformer.
Power stations produce electricity at 25,000 V. Step-up transformers change the voltage to the veryvalues needed to transmit electricity through theNational Grid power lines.Electricity is sent through these at 400,000 V, 275,000V or 132,000 V. This reduces energy losses duringtransmission but the voltages would be dangerousin homes. Step-down transformers are used locallyto reduce the voltage to safe levels. The voltage ofhousehold electricity is about 230 V.
step-uptransformersstep-downtransformersconsumers, forexample homes,factories and shops
There are 2 main types of waves:Transverse wavesAndLongitudinal wavesTransverse waves don’t need a medium totravel through (vacuum). They are mainlyradiation (e.g.: radio waves and microwaves).Longitudinal waves need a medium to travelthrough such as air. Example: sound waves.
Properties of waves1. Reflection2. Refraction3. Diffraction
REFLECTIONThe change in direction of a wave,such as a light or sound wave, awayfrom a boundary the wave encounters.Reflected waves remain in theiroriginal medium rather than enteringthe medium they encounter.
The law of reflectionThe angle of incidence equals theangle of reflection
RefractionThe bending of a wave, such as a light orsound wave, as it passes from one mediumto another medium of different density. Thechange in the angle of propagation dependson the difference between the index ofrefraction of the original medium and themedium entered by the wave, as well as onthe frequency of the wave.
DiffractionDiffraction is the bending of a wave aroundobjects or the spreading after passing througha gap.
Energy can be transferred by 3 mainprocess……..http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/mains/generatingelectricityact.shtmlConductionConvectionRadiation
ConductionConduction is the transfer of heat energythrough solids only. As heat energy Is transferthrough solids the solid particles vibrate abouttheir fixed point.
ConvectionConvection only occurs in liquids and gases.The particles vibrate but can move past eachother.
RadiationRadiation only occurs in gases. However thereare many types of radiation such as:1. Gamma radiation2. X-rays3. Ultra violet rays4. Visible light5. Infra red radiation6. Microwaves7. radiowaves
Gamma radiationGamma radiation is used to kill cancer cellsand sterilize surgical instruments. But howeverthey are dangerous and can kill your bodycells.
X-RAYSX-rays cannot pass through bones and metals.There fore it is used in hospitals to get a clearimage of broken bones etc. They can’t be seenor felt, but as they pass through your skin itdamages body cells which will cause cancer.
Ultraviolet raysWe can feel ultraviolet radiation as heat, andour skin respond to it by turning darker. Butgetting too much UV radiation can causeburns and skin cancer. (example: sun bed)
Visible lightIs the light we can see, which comes from the sun.
INFRA-RED RADIATION• All objects emit (give out) and absorb (take in)thermal radiation, which is also called infraredradiation. The hotter an object is, the moreinfrared radiation it emits.• Infrared radiation is a type of electromagneticradiation, which involves waves rather thanparticles. It doesn’t need a medium to travelthrough
Micro-wavesMicrowaves are electromagnetic rays.Microwave radiation is the radiating wavemovement in which microwave energy travels.Microwaves are absorbed by foods and othermaterials with high water content, andproduce heat. This is the operational principleon which microwave kitchen appliances work.
Finally, RADIO WAVES!Radio waves are made by various typesof transmitter, depending on the wavelength.They are also given off by stars, sparks andlightning, which is why you hear interferenceon your radio in a thunderstorm.
What is the big bang theory?The Big Bang theory is an effort to explainwhat happened at the very beginning of ouruniverse. Discoveries in astronomy andphysics have shown beyond a reasonabledoubt that our universe did in fact have abeginning. The big bang theory suggest thatworld began from an initial point. The bigbang theory is an effort to explain whathappened during and after that moment ofthe big bang!
The red shift.Our Sun contains helium. We know thisbecause there are black lines in the spectrumof the light from the Sun where helium hasabsorbed light. These lines form theabsorption spectrum for helium.Astronomers have found that the furtherfrom us a star is, the more its light is red-shifted. This tells us that distant galaxies aremoving away from us, and that the furtheraway a galaxy is, the faster its moving away.
The dark lines are moving to theblue end of the spectrum. Thisshows that the galaxies arecoming closer to us. This is knownas the blue shift. The universe isnot expanding!
When the dark lines aremoving towards the red endof the spectrum, this showsthat the galaxies are movingaway from you. So theuniverse is expanding!
Doppler effectWhen a vehicle with a siren passes you, anoticeable drop in the pitch of the sound ofthe siren will be observed as the vehiclepasses. This is an example of the Dopplereffect. An approaching source moves closerduring period of the sound wave so theeffective wavelength is shortened, giving ahigher pitch since the velocity of the wave isunchanged. Similarly the pitch of a recedingsound source will be lowered.