1 T3T4 Mains electricity Natural Science Gr. 6
2 2 Take out your HW diary NS: Do a mindmap on T3T2 (Conductors and insulators – use your tablet for extra information)
3 KEY WORDS Good conductor3 Good conductor Material that allows charges to flow through it freely. Good insulator Material that does not allow charges to flow through it. Good conductor Good insulator
4 KEY WORDS Decompose To decay or break down (rot).4 Decompose To decay or break down (rot). Renewable source of energy Sources of energy that cannot be used up, for example wind, water and the sun. Non-renewable source of energy Sources of energy that can be used up over time, for example coal, oil and natural gas.
5 Black powder left when coal has been burned.5 Turbine An engine with blades that are caused to spin by pressure from water, steam, or air. Soot Black powder left when coal has been burned. Power rating or Watt rating The amount of electricity an appliance uses. Hydro- electric power Electricity generated from flowing water.
6 Non-renewable sources of energy (Copy)6 Examples: Coal Oil Natural Gas
7 Deep under the surface of the earth.Where do these non-renewable sources of energy come from? Coal, oil and natural gas is called: Why do we call them fossil fuels? Why are these fossil fuels non-renewable? 7 Deep under the surface of the earth. Fossil fuels Because the are formed from the remains of dead plants and animals that lived millions of years ago. Because it takes millions of years for them to form.
8 Over millions of years ago these plants and animals where covered in layers of mud, sand and rock.The pressure of these layers, together with the heat of the Earth, slowly turned these decomposing animal and plant remains into fossil fuels. Due to all the pressure on these fossil fuels, a small lump of coal contains allot more energy than the same size of wood. 8
9 Where does the energy in these fossil fuels come from? How?9 The sun Photosynthesis
10 10 Pressure Heat of the Earth
11 11 FOSSIL FUELS
12 OIL (Copy) Oil is only found in certain places on Earth.12 Oil is only found in certain places on Earth. Mainly formed from animals and plants that lived millions of years ago It is a thick, black liquid. It is also called: It is found deep in the ground, between layers of rock. How is oil mined: A deep well is drilled. The oil is then pumped to the surface. Transported to refineries through pipelines or large tanker ships. in the ocean. Crude oil.
13 How oil is mined: On land. In the ocean. 13 PIPE LINE To refineries
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17 It can then be changed into different products like: Petrol Jet fuel 17 The oil is then refined (unwanted elements taken out) at the refineries. It can then be changed into different products like: Petrol Jet fuel Diesel fuel Paraffin Tar for roads Plastic Candle wax
18 So that we can smell it in case it leaks.NATURAL GAS (Copy) 18 It contains methane, a gas that burns very easily. it is found near oil in the ground. It is pumped from wells and sent to large containers through pipelines. Natural gas cannot be seen or smelt. A chemical is added to the gas to give it a smell. Why do you think this chemical is added? This chemical smells a bit like: So that we can smell it in case it leaks. Rotten eggs.
19 South Africa has a natural gas mine near Mosselbay, in the Western Cape.It is called: 19 PetroSA
20 COAL Mostly formed from the remains of plants.20 Mostly formed from the remains of plants. It comes in different forms: Looks like hard black rocks. Looks like soft brown dirt. Coal is used to make most of South Africa’s electricity.
21 Using coal to produce electricity:(Copy) 21 1. Coal is mined. 2. Coal is then taken to power stations by train. 3. At the power station it is burned to make steam. 4. The steam is used to turn a turbine which is connected to a generator. 5. The generator produces the electricity.
22 5. Generator produces the electricity.2. Coal is taken to power station by train. 1. Coal is mined. 22 4. Steam is used to turn a turbine connected to a generator. 3. At power station coal is burned to make steam. 5. Generator produces the electricity.
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24 Homework activity (Copy)24 Energy from the sun is changed to glucose in plants during photosynthesis. Animals eat these plants and use this energy to survive. When the animals and plants die they fall to the ground. Over time layers of sand, rocks and mud cover them. Pressure from these layers, combined with the heat of the Earth change their decomposing remains into fossil fuels. This process takes very long to occur. . TV Coal Power station Animals and plants Sun
25 Advantages and disadvantages of fossil fuels. (Copy)25 Advantages: Disadvantages: Huge amounts of energy can be generated using coal, oil and natural gas. Found in many places on earth. Easily transported by train, trucks and pipelines. We need to burn them to get the energy. This produces smoke and harmful gasses that cause air pollution. All fossil fuels give off carbon dioxide when they burn. They will not last forever (non-renewable). Mining causes damage to the natural environment.
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29 Cost of electricity (Copy)29 Name a few electrical appliances in your house: . How will we be able to tell if the appliance uses a lot of energy or only a small amount? Look at the watt (W) value of the appliance.
30 The higher the watt value the more electricity the appliance uses. What does kW stand for? How many watt is one kW? The watt rating is normally printed on the appliance or on the box. 30 Kilowatt 1000 watt 1 kW = 1000 watt
31 NS: Activity 2 (Only the questions)31 Take out your HW diary NS: Activity 2 (Only the questions) Activity 3 ( Only question 1- 4)
32 Homework activity 2 (MEMO)32 The geyser The radio 40c x 4 hours = 160c = R1.60 4) 50c to use the fridge in 1hour Fridge = 250W Iron = 1000W 1000W ÷ 250W = 4 50c x 4 = 200c = R2
33 6) R2,00 to have to Iron on for 1hour.5) R7,50 for the geyser to be on for 1,5 hours R7,50 x 7 = R52,50 6) R2,00 to have to Iron on for 1hour. Stove oven on for 3 hours? Iron = 1000W Stove oven = 1500W 1500W ÷ 1000W = 1,5 Stove oven on for one hour = R2,00 x 1,5 = R 3,00 Stove oven on for 3 hours = R3,00 x 3 = R9,00 33
34 Illegal connections 34 When people try to get electricity for free by connecting cables between their houses and the power lines. People making these illegal connections can easily be killed.
35 35 Even if they succeed in making these illegal connections, they will be taking extra current from the system. This can overload the system, causing wires to burn out and fires to start.
36 They recycle and sell the copper inside the electric cables.People also steal electric cables (cable theft). Why? Illegal connections and cable theft causes power outages. 36 They recycle and sell the copper inside the electric cables.
37 _____ Renewable ways to generate electricity What is global warming?37 What is global warming? Some scientists believe that we are warming the earth’s atmosphere. This is due to the huge amounts of carbon dioxide and other greenhouse gasses that are released when we burn fossil fuels. According them this causes climates to change all around the world. (This is known as climate change).
38 We might also have more severe storms, droughts and flooding.Due to the climate change some places are experiencing extreme weather conditions. Some areas are wetter while others are dryer. We might also have more severe storms, droughts and flooding. Some animals and plants species are facing extinction due to global warming. 38
39 Greenhouse 39
40 The Greenhouse effect 40
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42 The effects of global warming.42
43 The effects of global warming.43
44 The effects of global warming.44
45 The effects of global warming.45
47 Renewable sources of energyThese sources cannot be used up. For example: Movement energy from wind. Movement energy from flowing water. Heat and light energy from the sun. What is another word for movement energy? 47 Kinetic energy
48 Wind farm Wind power Wind = moving air. Used for:Windmills to pump water. Sailing. Generating electricity through the use of wind turbines. What do we call a lot of wind turbines placed in rows? 48 Wind farm
49 Blowing wind turns the turbine. The turbine is connected to a generator. The generator produces the electricity. A single wind generator can be used to supply a home with electricity. Wind farms are built to generate electricity for larger areas. Wind farms are built in areas where there is a lot of wind, because the electricity can only be produced when the wind blows. 49
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51 Hydro- electric power Hydro-electric power WaterWhat does ‘hydro’ mean? Water from snow and rains flow downstream from mountains and high ground. Running water has a lot of energy. The electricity generated from flowing water is called: 51 Water Hydro- electric power
52 Water in large dams can be used to generate electricity. The water flows out of the dam and over a turbine. The moving water turns the turbine which is connected to a generator near the dam wall. The generator produces the electricity. 52
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55 Yes Vanderkloof Dam Gariep DamDo we use Hydro- electric power in SA? Which dams in SA is used to generate electricity? 55 Yes Vanderkloof Dam Gariep Dam
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58 Solar Power The sun Where do we get solar energy from?The sun is our most important source of energy. We can use the energy from the sun to produce electricity. 58 The sun
59 To generate electricityHow can we use solar power? we can use the sun’s: 59 HEAT ENERGY LIGHT ENERGY + To warm water To generate electricity
60 What do we call this? 60 SOLAR PANELS or PHOTOVOLTAIC CELLS
61 Advantages and disadvantages of renewable sources of energy._______ 61 Advantages Disadvantages Can be re-used. Much cleaner sources of energy than fossil fuels. Do not pollute the air, because we do not have to burn them. We do not have to harm the environment when we use it to produce electricity. The source of energy (water, wind, the sun) is free. Producing electricity from these sources are expensive. Difficult to produce a large amount of electricity from these sources. They are not always available (The sun does not always shine and the wind does not always blow).
62 Indigenous knowledge (IK)This is knowledge that has been built up over many generations by people living in close contact with nature. Swazi people make predictions on things happening in nature based on the behaviour of animals, birds and insects. 62
63 Some of their predictions:63 When weaver birds which nest next to rivers build their nest high up in trees. Floods Predicts Predicts
64 Large numbers of saw-winged swallows in September and October.64 Heavy rain. Predicts Predicts
65 Very large numbers of butterflies and army worms during the farming season.Droughts Predicts 65 Predicts
66 66 Take out your HW diary NS: Do a mindmap on T3T4