Types of Energy and Their Uses - Physics Notes

76 Section Three — Physics Types of Energy and Their Uses Type of energy Description Example of uses Electrical From electric current. | | Televisions...

76 Section Three — Physics Types of Energy and Their Uses Type of energy Description Example of uses Electrical From electric current. | | Televisions = Ty, NW Ze Light From the Sun and light bulbs. Seeing at night “MN\ A, VIN Sound From things that make noise. Speakers a Kinetic [Moverent) Anything that's moving has it. | ge Cars Nuclear From nuclear reactions. [| Nuclear power stations Thermal From hot objects. Cooking food (Heat) Gravitational ‘ i Potential Anything that can fall has it. Be Roller coasters Elastic In stretched springs, = Sling shots Potential elastic and rubber bands. Chemical In foods, fuels and batteries. | Batteries Agree ; , vy vuttiidl l potential - vvvy : Kinetic, gravitationa are types = - and elastic potential 1/. , of mechanicalvty energy XS a yp td db rpg 4 Storing Energy| Some types of energy can be stored. Examples: 1) Chemical energy is stored in foods and fuels. 2) Kinetic energy is stored in moving objects. 3) Gravitational potential energy is stored in an object by lifting it up. 4) Elastic potential energy is stored by stretching or squashing a spring. 5) Thermal energy is stored in hot things. 6) Nuclear energy is stored in nuclear fuels. 1) True or false: all types of energy can be stored. 2) What two types of energy are involved when something is falling? Section Three — Physics Conservation of Energy 1) Energy can't 2) Energy can't 3) You can only change energy be created. be destroyed. from one type to another. electrical energy light and 4) A neat way of saying this is that energy is conserved. heat energy cc Ger ree. ~ Remember, thermal energy and — Nn = heat energy are the same thing. = Electrical Devices YrprtrrbiryyvVyV\NN Electrical devices transform (change) electrical energy into other types of energy. Example: Television A television transforms electrical energy into light energy, sound energy sound energy and a bit of heat energy. Electrical Energy => Light + Sound + Heat Energy electrical )))) energy Energy Transfer by Force When a force moves an object through a distance, energy is transferred. Example: A Crane Lifting an Object Chemical =e Kinetiovenensy = Gravitational “* i Potential a The energy stored in the The crane applies a force The object gets fuel used by the crane. to make the object move. lifted up. 1) True or false: when a force moves an object through a distance, energy is created. 2) What does a television transform electrical energy into? Section Three — Physics  Heat energy is transferred from one place to another when there is a difference in temperature. Heat Energy Transfer— Conduction These particles + +e 1) The particles in hot parts of a solid ===> vibrate a lot have more energy and move more. 2) These particles will bang into the particles next to them. They will transfer (pass on) some of their energy to them. ==>. 3) This is how heat energy travels through a solid. This is called conduction. 4) Conduction only happens in solids. 5) Metals are good conductors. They transfer heat energy quickly. Heat Energy Transfer — Convection Convection is where particles move from a hot place to a cooler one. It can only happen in liquids and gases. Liquids and gases are both types of fluid. 1) Ina colder fluid, particles are 2) In a hotter fluid, the particles have closer together. This means more energy and are further apart. cold fluids have a high density. This means hot fluids have a low density. 3) Hotter, less dense fluids will move above colder, denser fluids. This is called convection. 4) Convection is how radiators spread warm air around a room: As the warm air The warmer air A rises, cooler air falls rises above the and takes its place. colder, denser air. > ae Radiator heats | This carries on so you have air next to it | air flowing in a circle. This is called a convection current. This is how heat energy is transferred to the whole room. Section Three — Physics Heat Energy Transfer — Radiation 1) Heat is radiated (given out) from objects as infrared radiation (see p. 104). 2) You can feel infrared radiation — it's hot. a emitting infrared absorbing infrared infrared radiation radiation Ag > @ radiation Objects can emit (give out) Hotter objects emit more _—_ Cooler objects absorb heat and absorb (take in) heat radiation. This makes radiation. This makes heat radiation. their temperature fall. their temperature rise. Transfer of Sound Energy 1) Sound energy can be transferred from one place to another. 2) It is radiated (given out) as a sound wave from something making a noise. 3) The sound waves cause vibrations in the material they travel in. 4) The vibrations are passed on by particles. 5) So sound energy needs particles to travel. Viaton | | Salon of of particles pide! TT = TM|M H - 1) True or false: heat flows by convection in solids. 2) True or false: convection only happens in gases. 3) What type of energy is radiated as infrared radiation? 4) What type of wave is given out by something that is making a noise? Section Three — Physics  We can draw diagrams to show energy transfers. Useful and Wasted Energy 1) Energy is measured in Joules (J). 2) When energy is transferred from one form to another the total energy out is always the same as the energy put in. energy useful + put in wasted 3) Energy transfer diagrams show how much energy is energy transferred usefully and how much is wasted. Example: Light bulb A light bulb changes electrical energy into useful light energy and wasted heat energy. Here's the energy transfer diagram for a light bulb: pl lz, Sv vv vit 's dissipa ted. a_ Total energy in ~ Wasted energy Is spread out — (electrical) = ate means it. — a lost to the surt roumnd ngss.. ndiing _ and = 100 J =a90) The width of the Useful energy These add up to the arrow shows the (light) oe total energy in. amount of energy. =10) Calculating Efficiency Efficiency is the proportion (amount) of the energy in that is transferred into useful energy: — VN VAT py y 7, The more efficient U\VN Efficiency = Useful Energy. x 100% 7 something is, the ‘I PyVyyN Example: Kettle 9000 J of 1) The total energy supplied is the amount of wasted heat energy going in = 180 000 J 180 000 J of electrical (to the room) | 2) The useful energy is the energy being energy in 171000 J used to heat the water = 171 OOO J. of useful heat Efficiency = 171 000 + 180 000 x 100% (to the water) Efficiency = 95%. vp re, = Always give efficiency = —SF as a percentage (%). = Zrpedttrryvrvurns Section Three — Physics Calculating Power 1) Power is measured in watts (W). 2) Power is how fast energy is transferred Pawor Energy (in joules, J) from one form to another. = in watts, W) Time (i 3) The power of something can be af ae ) Time (in seconds, s) worked out using this equation: Example: A machine transfers 200 J in 10 seconds. What is the power of the machine? Answer: Power = Energy + Time = 200 + 10 = 20 W Calculating the Cost of Electricity 1) Electricity can be measured in units called kilowatt-hours (kWhr). 2) We have to pay for every unit of electricity we use in our homes. 3) You can work out the cost of using an appliance with this equation: = Power x Ti me x Cost of 1 kWhr Cost (in kW) (in hours) — (in pence) Example: Electricity costs 10p per kWhr. Find the cost of leaving a 1500 W tumble dryer on for 3 hours. Answer: First, change the units of power to kW: VV VE ?P rr ye 1000 W = 1 kW, so 1500 W = 1500 = 1000 = 1.5 kw ~ There are ie W = Z Ina : z Then use the equation to find the cost: — Cost = Power X Time X Cost of 1 kWhr = 1.5 kw x Sh xX 10p = 45p 1) True or false: efficiency is the proportion of the energy that is wasted. 2) What is the efficiency of a light bulb that transfers 100 J of electrical energy into 10 J of useful light energy? 3) Bob's electricity costs I5p per kWhr. Work out how much it costs him to use a 0.1 kW bulb for 4 hours. Section Three — Physics  The energy from renewable energy sources can be transformed into electrical energy. What are Renewable Energy Sources? 1) A renewable energy source is one that will never run out. 2) But they don't give out as much energy as the non-renewables (see page 96). 3) The renewables are hydroelectricity, wave power, tidal power, wind power, solar power, geothermal energy and biofuels. Hydroelectricity Hydroelectricity uses water stored behind a dam: Valleys are | The water is allowed out flooded. through the turbine when electricity is needed. The dam | catches | | and stores |water stored| rainwater. turbines generator Energy transfers: Gravitational — Kinetic enerei —s Electrical ‘ 7 Potential energy ie energy Of the water stored _ Of the water as it falls The kinetic energy of the turbine is behind the dam. and turns a turbine. _ transformed into electrical energy as it turns part of a generator. (©) Electricity can be made whenever it's needed. ) Building a dam is very expensive. Section Three — Physics Wave Power Waves move up and down, which turns a turbine: (©) H's useful on small islands. ) It's unreliable because waves aren't as big when the wind drops. () It doesn't give much energy. Energy transfers: water wave moves in |] 2 S a Kinetic energy m=> Electrical energy Of the waves which The generator transforms forces air to turn a the kinetic energy into turbine and a generator. electrical energy. Tidal Power 1) Tidal barrages are big dams built across rivers. They have turbines in them. 2) The tide flowing in and out turns the turbines. | | Sives loads of energy. Gas ©) H's very reliable because —— ot eae: See back | tides happen every day. Energy transfers: be ee “ Of the water which The generator transforms turns the turbine, which the kinetic energy into turns a generator. electrical energy. 1) True or false: renewable energy sources will never run out. 2) Give one advantage of using hydroelectric power to generate electricity. 3) What type of energy is transformed into electrical energy in a tidal barrage? Section Three — Physics  Wind Power Wind turbines transfer kinetic energy (from the wind) into electrical energy. — my 1) The wind has kinetic energy. 2) The blades turn a generator inside It turns the blades of a wind turbine. the turbine, which transforms the kinetic energy into electrical energy. Energy vA transfers: | Kinetic energy a> Electrical energy ©) They can be used on a small or large scale. Spe any ek / 7 (©) They're useful in remote places (where you ~ Using on a large @ might not be able to get mains electricity). - Hi aires ieee E fo ~ Pit, tet Va. @ They only work when it's windy. Solar Cells Solar cells transform light energy from the Sun into electrical energy. —S_ | Solar Cell Sap alba atl luau SA solar panel is 7 ~ made up of lots - vy of solar cells. ~ Vali PN \ NS Energy Light energy => Electrical energy transfers: ©) They're reliable in sunny places in the daytime. ©) They can be used on a small or large scale. ©) They're useful in remote places. (¢-) They don't work at night or when it's cloudy. Section Three — Physics Geothermal Energy Geothermal energy is heat from underground. ©) H's cheap to run. Water is pumped down & You can only use it where hot rocks Ss reece eer tere) [Turbinel are near the surface. There are not many places you can do it. It comes back Energy transfers: up as steam to Heat = Kinetic Electrical drive a turbine. at erat energy energy - energy From the Of the steam as__ As the turbine turns a generator hot rocks it rises up and it transforms kinetic energy to underground. _ turns the turbine. electrical energy. Biofuels. Plants Us Biofuel 1) Biofuels are made from plants. 2) Biofuels are burnt to heat up water to make steam. ae. a 3) The steam drives a turbine: ©) Biofuels are quick and cheap to make. Biofuel Nam ieee) =| Lots of land is needed to grow the plants for biofuels. Energy transfers: : ‘ ; ; Chemical energy mE Heat energy ge Kinetic energy —z> Electrical energy In the biofuels. Released when Of the steam As the turbine turns a the biofuel is as itturns —_ generator it transforms kinetic burnt. the turbine. energy to electrical energy. 1) True or false: wind turbines only generate electricity when it is needed. 2) What type of energy do solar cells convert into electrical energy? 3) Give one disadvantage of using geothermal energy. Section Three — Physics  What are Non-Renewable Energy Sources? 1) Non-renewable energy sources are ones that will run out at some point. 2) The non-renewables are: Fossil fuels Nuclear fuels (oil, coal and natural gas) Fossil Fuel Power Stations 1) Most of the electricity we use is generated (made) from fossil fuels in power stations. 2) Coal, oil and natural gas are burnt to heat water. Energy transfers: wanes. : Z Chemical energy ==> Heat energy a> Kinetic energy m= Electrical energy Stored in Released from Of the steam. The generator the fuel. the fuel and turns The steam turns transforms water to steam. a turbine, which kinetic energy to turns a generator. electrical energy. Nuclear Power Stations 1) Nuclear power stations work in a similar way to fossil fuel power stations. 2) The only difference is the heat energy comes from a nuclear reaction. Energy transfers: aoe : Z Nuclear energy ==> Heat energy m= Kinetic energy ma Electrical energy Stored in Released from Of the steam. The generator the fuel. the fuel and turns The steam turns transforms water to steam. a turbine, which kinetic energy to turns a generator. electrical energy. Section Three — Physics Advantages of Non-Renewable Energy Sources 1) Fossil fuels give out a lot of energy and nuclear fuels give out even more. 2) All the fuels are pretty cheap. 3) We can rely on them to provide us with electricity when we need it. Disadvantages of Non-Renewable Energy Sources 1) Non-renewable energy sources will run out. 2) They can harm the environment. Batteries and Fuel Cells 1) Batteries and fuel cells store energy. 2) They transform chemical energy into electrical energy: Chemical energy ==> Electrical energy 3) Batteries and fuel cells are useful when you can't get mains electricity or other sources of electricity. 4) Batteries are portable (they can be carried around). 5) But batteries and fuel cells can be more expensive to use than other energy sources. 1) Will non-renewable energy sources run out? 2) How are coal, oil and natural gas used to heat water in a power station? 3) Give two advantages of using non-renewables. Section Three — Physics 100 You have to know what all the words to do with waves mean. The Parts of a Wave 1) Waves transfer (move) energy from place to place. 2) All waves have amplitude, wavelength and frequency. 3) Below is a diagram of a wave: Amplitude Wavelength 1) This is the distance from the 1) This is the length of a full cycle of the wave. mid-point to a peak or trough. 2) For example, measuring the distance from 2) Amplitude is measured in peak to peak gives you the wavelength. metres (m). 3) Wavelength is measured in metres (m). Wavelength peak (top of wave) ZL. ~S V Amplitude mid-point \ \ un I Amplitude I ) ee. Sa I I Ss >| Wavelength trough (bottom of wave) J Frequency 1) This is how many whole waves pass a certain point every second... 2)... or the number of waves made each second. 3) Frequency is measured in hertz (Hz). > > 4) 1Hz is 1 wave per second. 3 waves in 1 second A = 8 iklz Section Three — Physics Wave Speed 1) Wave speed is the speed that a wave is travelling at. 2) \t's measured in metres per second (m/s). 3) This equation lets you work out the speed of a wave: Wave speed = Wavelength x Frequency (m/s) (m) (Hz) Pa Bw WN os I Standard Form 1) Standard form is a way of writing very big or small numbers. 2) For example, 6.4 x 10% is the same as 64 OOO. 3) To type 6.4 x 10% into a calculator, you would press: [6 [e [4 [ex] 4 | Example: A wave has a frequency of 6.4 x 10* Hz. Its wavelength is 0.1 m. What is its speed? Answer: Speed = wavelength x frequency = 0.1m Xx 6.4 x 10% Hz = 6400 m/s (= 6.4 x 10? m/s) 1) True or false: waves transfer energy. 2) What is frequency measured in? 3) What is the amplitude of a wave? 4) What is the wavelength of a wave? 5) A wave has a frequency of 1.6 x 104 Hz and a wavelength of 0.2 m. Find its speed. Section Three — Physics  Electromagnetic (e.m.) waves are really useful to us. Here is more about them... The Electromagnetic Spectrum el e feof} / 1) There are seven types of electromagnetic wave. Not o remember the order use: 2) They all have different wavelengths and frequencies. Read My Instructions 3) The seven types make up the electromagnetic spectrum: Visible Under X-ray Glasses SPa a Ae NSN Radio. 0 ; ble : 0) lean WEES: ave 10 S ole as Ras Long wavelength a Decreasing Wavelength es Short wavelength Low frequency ES Increasing Frequency ==> High frequency 4) The electromagnetic spectrum is continuous (there are no gaps between groups). 5) Each group has a range of wavelengths. For example, not all radio waves have the same wavelength (see below). eeee ~ Broadcasting means sending— “N B. a Uses of Radio Waves > a outtoalarge area. ~ “err Tig 4 \ VYVNN 1) Radio waves are used for: * broadcasting TV and radio signals. * transmitting (sending) satellite signals. 2) Different wavelengths of radio wave are used for the different things: Some short waves that pass through the atmosphere are used for satellites. | Some short Long-wave signals bend off the around the Earth. atmosphere. % Very short waves are used for FM radio and TV signals. Section Three — Physics  Uses of Microwaves Microwaves are used for: atellite TV signals 2) Satellite in space picks it up... 4 1) Satellite TV signals travel as m 8)...and sends microwaves from a transmitter MICROWAVES, 7 it back to Earth. to a satellite in space. 1) Transmitter sends out / ¢ 14) Signal picked 2) The satellite sends it to your signal. /