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43 Cards in this Set
- Front
- Back
When is heat energy transferred quickly?
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When there's a large temperature difference between a body and its surroundings
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Why does a liquid's average temperature decrease as the liquid evaporates? |
Because the particles with the highest energy evaporate first, leaving the low-energy particles behind, decreasing the liquid's average temperature |
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Describe the particles in a solid
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They have little energy and strong forces of attraction between them, so they stay close together in a fixed, regular arrangement
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Why are metals good conductors?
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Because they have free electrons which collide and transfer their energy more rapidly
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What is an 'effective' method of insulation?
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One that gives the largest annual saving
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What is a 'cost-effective' method of insulation?
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One that has the shortest payback time
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What do U-values tell us?
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How quickly heat can transfer through a material
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Do insulators have high or low U-values?
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Low
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What is an object's specific heat capacity? |
How much energy it can store |
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What is the unit for specific heat capacity? |
J/Kg⁰C |
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Why do heaters have a high specific heat capacity? |
So they can store lots of heat energy |
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What is the equation for efficiency? |
Useful Energy Out / Total Energy In |
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What is a kWh? |
The amount of electrical energy used by a 1 kW appliance in an hour |
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How can access to electricity improve someone's standard of living? |
They can power refrigerators to keep food fresh and use phones and computers to receive information |
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What are the four non-renewable energy resources? |
Coal, oil, natural gas and nuclear |
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Name three renewable energy resources |
Wind power, solar power and hydroelectric |
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How do non-renewable power stations generate electricity? |
The fossil fuel is burned, then this heat is used to heat water to produce steam, which turns a turbine that powers a generator |
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Give one advantage of gas power stations |
They don't use water, so have a quick start-up time |
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How do nuclear reactors produce heat? |
Through nuclear fission |
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How does a hydroelectric power station generate electricity? |
Water flows down a valley, turning a turbine as it goes past |
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What is the environmental disadvantage to hydroelectric power? |
A valley is flooded, which rots vegetation and causes the release of methane and carbon dioxide |
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What is pumped storage? |
When water is pumped back to the upper reservoir at times of low demand so that it can be released at peak demand |
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How does wave power generate electricity? |
The motion of the waves is used to drive a generator |
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How do tidal barrages generate electricity? |
The tide causes water to fill up estuaries, turning turbines as it passes through dams |
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What are the problems with tidal barrages? |
They prevent access by boat and can alter the habitats of wildlife |
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Where does geothermal energy come from? |
Hot rocks fairly near the surface |
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What is the difference between fossil fuels and biofuels? |
The organisms used to make biofuels were living much more recently |
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How is ethanol produced? |
By fermenting crops such as sugar cane |
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What is the main problem with nuclear power? |
The nuclear waste is very difficult to dispose of |
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What is the advantage of biofuels? |
They are carbon neutral |
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What are the disadvantages of biofuels? |
Deforestation usually occurs and the burning of the vegetation releases carbon dioxide and methane |
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What is carbon capture? |
Where the carbon dioxide from power stations is collected and pumped into underwater gas and oil fields |
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What is the national grid? |
A network of pylons and cables that covers the whole of Britain |
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Why is a high voltage chosen over a high current for disturbing electricity via the national grid? |
A high current means that lots of energy is lost as heat through the cables |
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What is the job of transformers? |
To step-up the voltage at one end and step it down again at the other |
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How can the increasing demand for electricity be met? |
By opening more power plants or increasing their output |
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How can demand for electricity be reduced? |
By consumers using more energy efficient appliances and being more careful not to waste energy |
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When are waves diffracted most? |
When passing through a small gap |
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Why are long-wave radio waves used for communication? |
They can diffract around the curved surface of the Earth |
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How can shorter wave radio waves be received over long distances? |
By bouncing them off of the ionosphere |
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Why are microwaves used for satellite communication? |
Because they can penetrate the Earth's atmosphere |
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What are infrared waves used for? |
Remote controls and optical fibres |
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Give a use of visible light |
Photography |