What are the best and worst absorbers of thermal radiation?
The best are black, dull surfaces and the worst are light, shiny surfaces
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How does heat pass through a single pane of window glass?
By conduction and convection
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Insulating a home costs £1800 and saves £50 a year. What is the payback time?
36 years
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Why does 'wasted energy' become less useful?
Because it becomes increasingly spread out
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In a certain device, 25% of the energy is usefully transferred. What is the energy efficiency of this device?
25%
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A coal-fired power station is 40% efficient. What does this mean?
40% of the chemical energy stored in the coal is transferred to electrical energy
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Using Source C, how much energy is transferred by a 500 W electric drill in 30 seconds?
15,000 J
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A 250 W computer is switched on for 4 hours. How many Units of electricity does it use?
1 Unit
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A 2 kW electric fire is switched on for 30 minutes. How many Units of electricity does it use?
1 Unit
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If one Unit of electricity costs 10p, how much will 30 units cost?
£3
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What is the distance from the crest of one wave to the crest of the next wave called?
The wavelength
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What are the units of frequency?
Hz (Hertz)
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What is the direction of a light wave to the direction of enerfy transfer?
Perpendicular to the direction of energy transfer
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What is shown in Source D?
Reflection
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What is shown in Source E?
Refraction
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What is shown in Source F?
Diffraction
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Using Source F, why do you need a small gap?
Because light has a small wavelength
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How do signals travel through optical fibres?
As infra-red radiation
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Why are microwaves used for satellite communications instead of radio waves?
Microwaves are used because they are not refracted by the atmosphere and because they can travel through the ionosphere. Radio waves are not used because they reflect off the ionosphere
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What piece of evidence supports the Big Bang theory?
The more distant galaxies are moving the quickest
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Why is the light from galaxies red-shifted?
They are moving away from us
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According to the Doppler effect, what happens to sound waves emitted at a constant pitch from a car moving towards you?
Their frequency increases, so their pitch increases
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What is the CMBR?
Cosmic Microwave Background Radiation
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Other cards in this set
Card 2
Front
What type of radiation do all hot objects emit?
Back
Infra-red radiation (IR)
Card 3
Front
What are the best and worst absorbers of thermal radiation?
Back
Card 4
Front
How does heat pass through a single pane of window glass?
Back
Card 5
Front
Insulating a home costs £1800 and saves £50 a year. What is the payback time?
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