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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