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# 9 i energy and electricity (whs)

## on Mar 29, 2014

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## 9 i energy and electricity (whs)Presentation Transcript

• 29/03/14 Energy andEnergy and ElectricityElectricity
• 29/03/14 Types of energyTypes of energy Type 3 example sources Heat Kinetic (movement) Nuclear Sound Light Chemical Electrical Gravitational potential Elastic potential Type
• 29/03/14 Energy changesEnergy 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
• Conservation of EnergyConservation of Energy In any energy change there is ALWAYS some “waste” energy: e.g. a light bulb: Electricity Light + 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.
• 29/03/14 Energy Transfer diagramsEnergy Transfer diagrams A light bulb uses 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
• 29/03/14 Example questionsExample questions Consider a kettle: 1) Work out each energy value. 2) What is the kettle’s efficiency? Sound energy Wasted heat Heat to water 2000 J/s electrical energy 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?
• 29/03/14 Electrical EnergyElectrical Energy Consider a simple circuit: Words – electrical (x2), light, chemical The job of the battery is to convert ______ energy into _________ energy… The job of the bulb is to convert the _________ energy it receives from the battery into ______ energy.
• 29/03/14 Electrical EnergyElectrical Energy Energy Hi. I’m Ernie Electron and I’m going to show you how I get energy around a circuit.
• 29/03/14 Electrical EnergyElectrical Energy Energy Hi. I’m Ernie Electron and I’m going to show you how I get energy around a circuit.
• 29/03/14 Electrical EnergyElectrical EnergyHi. I’m Ernie Electron and I’m going to show you how I get energy around a circuit. Energy
• 29/03/14 FuelsFuels A “fuel” is something that can be burned to release heat and light energy. The main examples are: Coal, oil and gas are called “fossil fuels”. In other words, they were made from fossils.
• 29/03/14 Renewable energy sourcesRenewable energy sources Wind Tidal Hydro-electric Geothermal Biomass Wave
• 29/03/14 Power stationsPower stations Cooling tower Turbine Generator TransformerBoiler
• 29/03/14 What does each part do?What does each part do? The boiler is where fuel is burnt to boil water Steam from the boiler is used to turn a turbine The turbine is connected to the generator. It acts like a dynamo – changing kinetic energy into electricity. The steam cools down and condenses back into water in the cooling tower