Untitled (Kendrick Lamar) <- JK

Chemical energy: Energy stored in a fuel for example food released when chemical reactions take placeKinetic energy:Energy of a moving objectGravitational potential energy:Energy due to it's position higher more gpeElastic potential energy:energy of an object when squashed or stretched in a springy objectEnergy transfer:energy can be transformed from one form to another for example:GPE>Kinetic Energy>Heat + Sound energyConservation of energy:Energy cannot be created or destroyed applies to all kind of energy formsUseful energy:energy that is used for the desired purposeWasted energy:energy produced that does not serve the desired purposeAll energy is transferred to the surrondings which make it hotter and as energy dissipates it becomes to transferEnergy and effiency:Weight is measured in Newtons (n), energy is measured in Joules (J)Input energy(energy supplied)=useful energy + wasted energyeffiency=useful/total energy *100no machine can be 100% efficient because you can get more energy than you put inImproving effiency:friction becuause of moving parts hitting each other causes heating - lubricate partsResistance of wire cause wire to get hot when current pass through - have less eletrical resistant partsAir resistance causes energy transfer to surrondings - Make the object more streamlinedSound created by machinery - Make parts vibrate less by tightening

Eletrical appliances:Can tranfer energy into a useful one at the flick of a switchUse of everyday appliances: Light bulb, eletric heater, electric toaster, electric kettle, hairdryer, electric motor and computer disc driveDesigned for particular purpose should waste as little energy as possibeElectric power:Power is the energy supplied per second measured in watts or kilowattsP=E/t E is energy transferred to appliance in Joules t is the time taken in secondsUsing electrical energy:Energy supplied to any appliance depends on how long it is used for and the power supplied to itE=P*t E is in kWhElectricity meter measures how much energy is used in the house total cost=number of kWh used * cost per kWhCost effectiveness matters:Must make sure appliances are cost effective (value for money)To compare must consider: Capital cost such as buying and installingRunning cost including fuel and maintaineceenvironmental costPayback time= cost / savings per year

Fuel for electricity:Almost all electricity is generated in power stationsIn coal or oil-fired power stations and in most gas fired powered stations the burning fuel heats water in a boiler which produces steam which drives a turbine and that turns a electricity generator.Coal oil and gas are fossil fuelsBiofuels: Methane is a biofuel as it is renewable and carbon neutralNuclear power: Energy is released when nucleas of a uranium atom is unstable and split in two called nuclear fission. Energy form core transferred by a fluid called coolant which is pumped through the core, coolant flows through pipe to heat exchanger then back to reactor core. Energy from coolant used to turn water to steam in heat exchanger steam drives turbine which turns electricity generator. Uranium or plutonium releases much more energy per kg than fossil fuelsWind turbine: Electricity generator at the top of a narrow tower wind drives turbine's blade around turns generatorWave power: Generates electricity moves a floating generator up and downHydroelectric power: Water collects from rainfall in a reservoir water flows down hill drives turbine generates electricity generators at the foot of the hillTidal power: traps water at high tide behind a barrage then release the high tide into sea through turbines  drive generatorSolar radiation: Generate electricity using solar cells which are flat solid cells which by the process of heating water Solar power tower: Uses thousands of flat mirrors to reflect sunlight on to a large water tank, water in tank turned to steam by the heating effect of solar radiation steam pumped to ground level turns electricity generatorGeothermal energy: comes from energy released by radioactive substances, deep within the Earth energy released heats the rock, energy is transferred by heating  towards the Earth's surface. Water pumped down to these rocks to produce steam steam drives electricity turbine at ground level. Heating flowing underground is called ground heat.energy and the environment:Through burning of fossil fuels carbon dioxide released causes global warming also produces sulfur dioxide which causes acid rain but can be removed before burning, fossil fuels are non-renewable Carbon capture and storage could be used to stop carbon dioxide emissionsNuclear fuels produce radioactive wasteRenewable energy resources can affect plant and animal lifeThe National Grid: Network of cables that distribute electricity from power stations to homes and other buildings. Step up transformers step up voltage to the grid voltageStep down transformers at local substations step  the grid voltage down to 230V for use in homes and officesPower and the grid voltage: reduces energy loss and system more efficient by step up transformer lower voltage at the end of grid before can be usedBig energy issues:Gas fired power stations and pumped storages stations can meet variations in demandNuclear , coal and oil power stations can meet base load demandsNuclear power stations, fossil fuel power stations using carbon capture and renewable energy are all likely to contribute to future energy supplies

WavesThe nature of waves:Used to transfer energy and transfer informationTransverse waves vibrate at right angles to the direction of energy transfer of the waves. All electromagnetic waves are transverse wavesLongitudinal waves vibrate parrelel to the direction to the energy transfer example is sound wavesMechanical waves, need a meduim, may be transverse or longitudalMeasuring wavesAmplitude is the height of the wave or depth from position of restFrequency is the number of wave crest passing a point in one secondWavelength is the distance from one wave crest to the next wave crest Wave speed m/s = frequency Hz * wavelength m Reflection:Normal at a point on a mirror is perpendicular to the mirrorAngle of incidence is angle between the incident ray and the normalAngle of reflection is the angle between the relfected ray and the normalLaw of reflection states the angle of incidence = angle of reflectionRefraction:It's the change of direction of waves when they travel across a boundaryWhen a light ray refracts as it travels from air into glass angle of refraction less than angle of incidenceLight ray refracts as it travels from glass angle of refraction is more than the angle of incidenceDiffraction:Spreading out of waves wen they pass through a gap or round the edge of an obstacleNarrower the gap greater the diffraction is If radio waves do not diffract enough when they go over hills, radio an TV reception will be poorSound:Frequency range of the normal human ear is from 20Hz to 20,000HzSound waves are vibrations that travel through a medium  cannot travel through a vacuumEchoes are due to sound waves reflected from a smooth hard surfaceMusical sounds:Pitch of a note increases if the frequency of the sound wave increasesLoudness of sound increases if the amplitude of the sound wave inreasesVibrations created in a instrument when it is played produce sound waves

Electromagnetic SpectrumRadio wavesMicrowaves Infrared radiationvisible lightUltra violet X- rayGamma radiationWave speed equation used to calculate the frequency or wavelength of electromagnetic waves v- f*hv= wave speedf=frequenyfunny h = wavelength in mLightWhite light contains all the coloursInfrared radiationUsed to carry signals from remote handsets and inside optical fibresMicrowavesCarry sattellite TV programmes and mobile phone callsRadio wavesUsed for radio and TV broadcasting, radio communications and mobile phone callsMicrowaves and radio waves can cause internal heating and infrared radiation can cause skin burncommunicationsRadio waves:  of different frequencies used for different purposes because the wavelength of waves affect how far they can go how much they spread and how much information they carryMicrowaves are used for satellite TV signalsFurther research is needed to evaluate whether or not mobile phones are safe to useOptical fibres are very thin transparent fibres that are used to transmit signals by light and infrared radiationExpanding universe:Red shift of galaxy is the shift to longer wavelengths of the the light from it because the galaxy is moving away from usFaster a distant galaxy is moving the greater the red shiftAll the distant galaxies show is a red shift the further away a distant galaxy is the greater the red shift happening because the universe is expandingThe Big Banguniverse started from the big bang, a massive explosion from a very small pointBeen expanding ever since big bang Cosmic microwave radiation is the electromagnetic radiation created just after the big band can only be explained by the Big BangBig yawn or big crunch

2 Energy and effiency

3: Eletrical Appliances

Generating Electricity

Waves

Electromagnetic Spectrum