Physics OCR, P3

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What issues does the demand for energy cause?
the availability of energy sources and the environmental effects of using these sources
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What are the main primary sources of energy?
fossil fuels, biofuels, wind, waves and radiation from the sun
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Why is electricity a secondary energy source?
it is generated form another energy source
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Why are power stations that burn fossil fuels bad?
they produce carbon dioxide which contributes to global warming and climate change
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What happens when an electric current passes through a component?
energy is transferred from the power supply to the component and/or the environment
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What is power (Watts,W)?
a measure of the amount of energy it transfers each second
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What is the equation for amount of energy transferred?
energy transferred = power x time (E=P x T)
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What is the equation to calculate the rate at which an electrical device transfers energy?
power = voltage x current (P=V x I)
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What is the equation for percentage of efficiency?
%efficiency =(usefully transferred energy/total energy supplied) x100
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Why is electricity convenient?
it is easily transmitted over distances and can be used in many ways
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What is mains electricity produced by?
generators
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How do generators produce a voltage?
across a coil of wire by spinning a magnet near it
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What happens the bigger the current supplied by a generator?
the more primary fuel it uses every second
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How do power stations work?
heat boils water and produces steam, which drives the turbines and power the generators. Electricity produced sent to step-up transformer and the national grid. High voltages reduced by step-down transformer and then to our homes.
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Why is electricity distributed at high voltages?
to reduce energy losses
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What are disadvantages of nuclear power stations?
produce radioactive waste
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What does radioactive waste emit?
ionising radiation
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What is irradiation?
being exposed to a radiation source outside your body
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What is contamination?
if any part of a radiation source got on your clothes or entered your body. This would continually expose you to dangerous ionising radiation and therefore is a greater threat to your health than irradiation
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What does increased exposure to ionsing radiation cause?
damage to living cells, eventually leading to cancer or cell death
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what is the mains supply voltage to our homes?
230 volts //240v
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What does the choice of energy source depend on?
environmental impact, economics, waste produced and carbon dioxide emissions
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What are advantages of fossil fuels?
high energy output, easily distributed and efficient
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What are disadvantages of fossil fuels?
burning generates greenhouse gases, non-renewable and products damage the environment
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What are advantages of nuclear power?
reliable, no greenhouse gases and high energy output
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What are disadvantages of nuclear power?
disposal of nuclear waste is difficult, expensive, damage to environment
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What are advantages of biofuels?
renewable and inexhaustible supply
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What are disadvantages of biofuels?
needs a large area of land to produce, burning leads to greenhouse gases and expensive to produce
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What are advantages of renewable energy?
renewable, no greenhouse gases and no solid or liquid waste
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What are disadvantages of renewable energy?
expensive, limited locations and not as reliable
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What do we need to ensure a security of electricity supply nationally?
a mix of energy sources
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Other cards in this set

Card 2

Front

What are the main primary sources of energy?

Back

fossil fuels, biofuels, wind, waves and radiation from the sun

Card 3

Front

Why is electricity a secondary energy source?

Back

Preview of the front of card 3

Card 4

Front

Why are power stations that burn fossil fuels bad?

Back

Preview of the front of card 4

Card 5

Front

What happens when an electric current passes through a component?

Back

Preview of the front of card 5
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