P2 Living for the future

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What type of current does a photocell produce?
Direct Current (dc)
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How does a photocell produce an electric current?
Silicon atoms in the photocell absorbs the light energy, causing electrons to be knocked out of the silicon atoms. These electrons are then free to flow, creating a direct current.
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What are the advantages of using a photocell to generate electricity?
Low maintenance, renewable resource, no fuel required, energy resource is free, can be used in remote locations, no carbon dioxide produced
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What are the disadvantages of using a photocell to generate electricty?
Cannot generate electricity at night, affected by time of day/year (intensity effects the output), large number of cells required to generate electricity of conventional power station
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What is passive solar heating?
Infrared radiation passes through the windows of a building and is absorbed by surfaces inside, heating them up.
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How does the Sun cause winds?
Winds are convection currents set up in the Earth's atmosphere by uneven heating by the Sun.
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What are the advantages of using a wind turbine to generate electricity?
Renewable resource, no waste produced
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Whare are the disadvantages of using a wind turbine to generate electricity?
Create noise pollution, wind speed varies changing the output power, visually unappealing, lots needed to generate sufficient electrical energy
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What is an alternating current?
An alternating current is one which is created by switching the voltage smoothly between positive and negative values during generation, causing the current to reverse direction rapidly.
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What is the UK mains voltage value?
230V
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What is the frequency of UK mains electricity?
50Hz
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What three things are needed for the dynamo effect to work?
Magnet, wire and movement
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Describe how the dynamo effect produces an electric current
A piece of wire is moved between the poles of a magnet, This induces (creates) a voltage.
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What electrical device is used to measure the current in a circuit?
Ammeter
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How can the size of the current produced by the dynamo effect be increased?
Use stronger magnet, coil the wire (making it longer in the field), move the wire/magnet faster
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What is the formula for efficiency?
efficiency = (useful energy output / total energy input)*100%
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What is the National Grid?
The national network of electrical cables connecting the power stations to end users in homes and factories.
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What is the purpose of a transformer in the National Grid?
Step-up / Step-down the voltage in the network to allow the electrical current to be transmitted at very high voltages
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Why is electricity transmitted at very high voltages in the National Grid?
To make the current very small, reducing energy loss through heating of the wires.
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What are the primary greenhouse gases?
Water vapour, methane, carbon dioxide
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What is the greenhouse effect?
When gases within our atmosphere absorb infrared radiation and prevent this from radiating into space.
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What is the equation for electrical power?
Power = current * voltage
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What are the units of Power?
Watts
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What does the kilowatt hour (kWh) measure?
Energy
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What is the equation used to measure energy transferred by an electrical device?
energy transferred (kWh) = power (kW) * time (h)
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What is the formula used to calculate the cost of electricity supplied to an electrical device?
cost (p) = energy transferred (kWh) * cost per unit (p/kWh)
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What are fossil fuels?
Coal, oil, natural gas; made from the remains of ancient plants and sea creatures found buried underground
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What are the advantages of using fossil fuels to generate electricity?
Supplies large amounts of electricity, simple to produce electricity from, reliable supply
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What are the disadvantages of using fossil fuels to generate electricity?
Releases carbon dioxide gas when burnt, limited supply (will run out)
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What are the advantages of biomass as a fuel to produce electricity?
Uses products that may otherwise have been wasted, power stations can also supply hot wate to local industry/houses. Carbon neutral (no extra carbon dioxide released from process)
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What are the disadvantages of biomass as a fuel to produce electricity?
Releases atmospheric pollutants, land that could otherwise be used for crops used to grow biofuel crops instead, power plans themselves can be visual pollutant (ugly)
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What are the advantages of using nuclear power?
Doesn't produce carbon dioxide, lots of electrical energy supplied, reliable supply of fuel (thousands of years worth left)
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Other cards in this set

Card 2

Front

How does a photocell produce an electric current?

Back

Silicon atoms in the photocell absorbs the light energy, causing electrons to be knocked out of the silicon atoms. These electrons are then free to flow, creating a direct current.

Card 3

Front

What are the advantages of using a photocell to generate electricity?

Back

Preview of the front of card 3

Card 4

Front

What are the disadvantages of using a photocell to generate electricty?

Back

Preview of the front of card 4

Card 5

Front

What is passive solar heating?

Back

Preview of the front of card 5
View more cards

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