1. 09/07/2016Energy

2. The ULTIMATE energy source The sun is the ultimate source of all our energy.

3. 09/07/2016 The 9 types of energy Type3 example sources Heat Kinetic (movement) Nuclear Sound Light Chemical Electrical Gravitational potential Elastic potential

4. 09/07/2016 Energy Stores EnergyStored inUses CHEMICAL KINETIC GPE ELASTIC POTENTIAL THERMAL NUCLEAR

5. 09/07/2016 Energy changes To describe an energy change for a light bulb we need to do 3 steps: Electricity Light + heat 1) Write down the starting energy: 3) Write down what energy types are given out: 2) Draw an arrow What are the energy changes for the following…? 1)An electric fire 2)A rock about to drop 3)An arrow about to be fired

6. 09/07/2016 Conservation of Energy In any energy change there is ALWAYS some “waste” energy: e.g. a light bulb: ElectricityLight + heat In this example HEAT is wasted – it’s given to the surroundings. Waste energy is virtually always heat and it’s always given to the surroundings.

7. 09/07/2016 Heat and Temperature This cup of coffee will ____ ____ because it is _____ ____ heat energy into the surroundings. This drink (taken out of the fridge) will _____ ___ because it is _____ ___ heat energy from the surroundings. Heat is a type of energy that will flow from a warm area to a colder one. For example… Words to use – giving out, warm up, taking in, cool down

8. 09/07/2016 Conduction is all about when heat is transferred through a _________. The heat is passed on by ___________ in the molecules. These vibrations get BIGGER when the solid has more ENERGY (i.e. when it is being __________). Metals are _______ conductors than non-metals. This is because the heat is carried by free ________ that can carry the energy around the metal and give it to other electrons and ions.Conduction Words – vibrations, electrons, solid, heated, better (I suggest putting in a link to animations of heating different solids – these are found on www.educationusingpowerpoint.org.uk and click on “animations”.)www.educationusingpowerpoint.org.uk

9. 09/07/2016Convection Convection is all about when a gas or liquid (“fluid”) moves and carries heat with it. When the fluid is heated it ____________. This means that it will become less __________ than the colder fluid around it. Because of this the warmer fluid will try to “_______” over the colder fluid, and this is why warm air rises. This is called a convection ___________. This is how heat reaches us from the ___________ in this room. In CONDUCTION the heat was passed on by VIBRATIONS in a SOLID In CONVECTION the heat is passed on by the FLUID expanding, rising and TAKING THE HEAT with it Words to use: expands, radiators, dense, heated, current, float

10. 09/07/2016 Some questions on convection… 1)Freezers in supermarkets are often left open to the air. Explain why the food does not melt easily. 2)Explain why a hot air balloon rises in the air. 3)Explain why an ice cube floating at the top of a drink will cool all of the drink.

11. 09/07/2016Radiation When you wear a black t-shirt on a hot, sunny day you would feel ______ than if you wore ____. This is because black _______ infrared radiation (i.e. heat) from the sun better than white does. I’m very hot! I’m cool!

12. 09/07/2016 Some examples of radiation

13. 09/07/2016 Some examples of radiation

14. 09/07/2016 Radiation is when heat moves around in electromagnetic _________ like light does. Any hot object will emit heat radiation – the hotter it is, the more radiation it emits. This type of radiation is called __________, and too much of it will cause _________. Dark, matt colours will absorb AND emit the _____ infra-red radiation, and light, shiny colours will ________ it. The main difference with radiation is that conduction and convection could ONLY happen in solids, liquids or gases, whereas radiation will happen through an _____ _____. This is just as well, as otherwise we wouldn’t be able to get any heat from the ___.Radiation Words – sun, reflect, infra-red, waves, most, empty space, sunburn Anything HOT emits HEAT RADIATION – the hotter it is, the more infra red radiation it emits

15. ENERGY TRANFER: MOVING THINGS 09/07/2016 When any object is moved around work will need to be done on it to get it to move (obviously). We can work out the amount of work done in moving an object using the formula:

16. 09/07/2016 Energy and Power The POWER RATING of an appliance is simply how much energy it uses every second. In other words, 1 Watt = 1 Joule per second E TP E = Energy (in joules) P = Power (in watts) T = Time (in seconds)

17. 09/07/2016 Some example questions 1)What is the power rating of a light bulb that transfers 120 joules of energy in 2 seconds? 2)What is the power of an electric fire that transfers 10,000J of energy in 5 seconds? 3)Farhun runs up the stairs in 5 seconds. If he transfers 1,000,000J of energy in this time what is his power rating? 4)How much energy does a 150W light bulb transfer in a) one second, b) one minute? 5)Shaun’s brain needs energy supplied to it at a rate of 40W. How much energy does it need during a physics lesson? 6)Damien’s brain, being more intelligent, only needs energy at a rate of about 20W. How much energy would his brain use in a normal day?

18. 09/07/2016 Calculating the cost of electricity Clearly, this depends on two things: the POWER RATING of the appliance and HOW LONG you leave it on for. Electricity is measured in “units”, also called “kilowatt hours” (kWh). To work out how much something would cost use two steps: 1)Find out how many units have been used: No. of units = Power rating x Time appliance is on for in kWh in kWin hours 2) Multiply the number of units by how much each one costs: Cost of electricity = no. of units used x cost of each unit in pencein kWhin pence

19. 09/07/2016Efficiency Efficiency is a measure of how much USEFUL energy you get out of an object from the energy you put INTO it. Efficiency = Useful energy given out by the device Energy put into it e.g. if 2000 joules of electrical energy are put into a kettle and 500 joules of heat energy are gained from it, its efficiency is 500/2000 x 100% = 25% x100%

20. 09/07/2016 Some examples of efficiency… 1)5000J of electrical energy are put into a motor. The motor converts this into 100J of movement energy. How efficient is it? 2)A laptop can convert 400J of electrical energy into 240J of light and sound. What is its efficiency? Where does the rest of the energy go? 3)A steam engine is 50% efficient. If it delivers 20,000J of movement energy how much chemical energy was put into it?

21. 09/07/2016 Energy Transfer diagrams Consider a light bulb. Let’s say that the bulb runs on 100 watts (100 joules per second) and transfers 20 joules per second into light and the rest into heat. Draw this as a diagram: 100 J/s electrical energy “Input” energy“Output” energy 80 J/s heat energy (given to the surroundings) 20 J/s light energy

22. 09/07/2016 Example questions Consider a computer: 150 J/s electrical energy 10 J/s wasted sound 20 J/s wasted heat Useful light and sound 1)How much energy is converted into useful energy? 2)What is the computer’s efficiency?

23. 09/07/2016 Renewable vs. non-renewable fuels A ________ energy source is blatantly one that can be _______ (“renew = make again”), e.g. _____, solar power etc. A ___________ energy source is one that when it has been used it is gone forever. The main examples are ____, oil and gas (which are called ______ ____, as they are made from fossils), and nuclear fuel. Words – non-renewable, coal, renewable, fossil fuels, wood, renewed

24. 09/07/2016 Other ways of generating electricity… Wind Tidal Wave Hydro-electric

25. 09/07/2016 SourceDisadvantages Wind Depends on weather, visual pollution, difficult to “store” Wave Harms wildlife, depends on size of waves, depends on weather Tidal Depends on size of tides, harms wildlife, visual pollution Hydroelectric Habitats can be destroyed, only good as a “short term” supply Also, these sources all have high setting up costs

26. 09/07/2016 Other options… Geothermal energy – water is heated using heat given off by _________ rocks underneath the surface of the Earth Solar energy – using solar panels ______ can be converted straight into electricity Although renewable fuels are ____, the energy we get from them is “_______”. This means that we have to spend a lot of money on generators to make them worthwhile. This is why solar panels are only used in small things (like calculators) or extremely remote locations (like ____________). Words – dilute, radioactive, free, satellites, light

27. 09/07/2016Summary Renewable sources of energy are cheaper, cleaner and will not run out. However, they are incapable of providing all the energy we need, so we will have to go on burning fossil fuels for now.

28. 09/07/2016 Some definitions… Transverse waves are when the displacement is at right angles to the direction of the wave… Longitudinal waves are when the displacement is parallel to the direction of the wave…

29. 09/07/2016 Some definitions… 1) Amplitude – this is “how high” the wave is: 2) Wavelength ( ) – this is the distance between two corresponding points on the wave and is measured in metres: 3) Frequency – this is how many waves pass by every second and is measured in Hertz (Hz)

30. 09/07/2016 The Wave Equation The wave equation relates the speed of the wave to its frequency and wavelength: Wave speed (v) = frequency (f) x wavelength ( ) in m/s in Hz in m V f

31. 09/07/2016 Some example wave equation questions 1)A water wave travels through a pond with a speed of 1m/s and a frequency of 5Hz. How far apart are the waves? 2)The speed of sound is 330m/s (in air). When Ricky hears this sound his ear vibrates 660 times a second. What was the wavelength of the sound? 3)Purple light has a wavelength of around 6x10 -7 m. If its frequency is 5x10 14 Hz what is the speed of light? 4)Red light travels at the same speed. Work out its frequency if its wavelength is about 4x10 -7 m.

32. 09/07/2016 Light travels VERY FAST – around 300,000 kilometres per second. At this speed it can go around the world 8 times in one second.

33. 09/07/2016 The electromagnetic spectrum Gamma rays X-raysUltra violetVisible light Infra redMicrowavesRadio/TV Each type of radiation shown in the electromagnetic spectrum has a different wavelength and a different frequency: Each of these types travels at the same speed through a _______ (300,000,000m/s), and different wavelengths are absorbed by different surfaces (e.g. infra red is absorbed very well by ___________ surfaces). This absorption may heat the material up (like infra red and _______) or cause an alternating current (like in a __ _______). Words – black, microwaves, long, short, TV aerial, vacuum High frequency, _____ wavelength Low frequency, _____ (high) wavelength γ

34. 09/07/2016 Ionosphere Transmitting information As we said before, different types of electromagnetic radiation can be used to send different types of information, e.g. an optical fibre: Optical fibres have two main advantages: they can send more information compared to electrical cables of the same diameter and with less signal weakening. Another example is radio waves: The longer wavelength waves are transmitted by being reflected off the ionosphere (an electrically charged layer in the Earth’s atmosphere).

35. 09/07/2016 Transmitting information Sounds can be transmitted long distances by converting them into electrical signals first: Radio waves can also be used as “carrier waves”: Signal____ wave______ waveTransmitter Wave is demodulated back into a ____ Words – signal, frequency, modulated, carrier, sound, amplified A microphone converts ______ waves into electrical signals with the same amplitude and ________. These waves are then transmitted through cables where they are regularly _________ to reduce signal loss.