9 i energy and electricity (whs)
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Energy Energy and and
ElectricitElectricityy
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Types of energyTypes of energy
Type 3 example sources
Heat
Kinetic (movement)
Nuclear
Sound
Light
Chemical
Electrical
Gravitational potential
Elastic potential
Type
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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.
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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
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Example questionsExample questionsConsider 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?
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Electrical EnergyElectrical EnergyConsider 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.
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Electrical EnergyElectrical Energy
Energy
Hi. I’m Ernie Electron and I’m
going to show you how I get energy around a circuit.
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Electrical EnergyElectrical Energy
Energy
Hi. I’m Ernie Electron and I’m
going to show you how I get energy around a circuit.
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Electrical EnergyElectrical EnergyHi. I’m Ernie Electron and I’m
going to show you how I get energy around a circuit.
Energy
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FuelsFuelsA “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.
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Renewable energy sourcesRenewable energy sourcesWind
Tidal
Hydro-electric
Geothermal
Biomass
Wave
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Power stationsPower stations
Cooling tower
Turbine
Generator
Transformer
Boiler
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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