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31 Cards in this Set
- Front
- Back
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Why are microwaves used for satellite communication? |
They can pass through the earth's atmosphere |
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Why are radiowaves so useful in communication? |
They are extremely fast. They have large wavelengths so they can be diffracted easily and received behind hills and valleys. They can also be bounced off of the earth's ionsphere meaning they can be received behind mountains |
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What is diffraction? |
The spreading out of waves at the edges when they pass through a gap or object. |
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What are the disadvantages of nuclear power stations? |
They have a long start up time. They produce nuclear waste that is hard to dispose of. It is a non-renewable source. |
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What is convection? |
The tendancy of colder, more dense fluid particles to displace warmer less dense ones forming a current. |
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What is the difference between longitudinal and transverse waves? |
Longitudinal waves require particles and travel parallel to the energy. |
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How are fossil fuels made? |
Dead plants and animals are buried under sediments stopping them from decomposing. They are pressed, heat and squeezed over million of years turning them into fossil fuels. |
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A watt is a measurement of... |
Power. |
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What are the advantages and disadvantages of overground cables? |
They are easier to fix They are cheaper
They can be noisy They are dangerous They are more likely to sustain damage. |
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How is energy produced in a geothermal power plant? |
A pipe is drilled down to an underground hot pool or water is pumped down to hot rocks. The steam that comes out drives a turbine which powers a generator that produces electricity. |
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What are the 10 forms of energy? |
Thermal Light Kinetic Sound GPE Elastic Electrical Chemical Magnetic Nuclear
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In electrical equipment, how is most energy lost? |
Heat to the surroundings. |
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What factors affect the absorption of heat? |
An objects colour and surface area. |
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What factors affect the rate of energy transfer? |
Surface area Distance between objects Temperature difference |
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Where is total internal reflection used? |
Fibre optic connections |
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Describe the doppler effect? |
As the source of the sound moves towards you, the waves are bunched together increasing the frequency and therefore the pitch. As it move away, the waves spread out decreasing the frequency therefore decreasing the pitch. |
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What is refraction? |
The changing of the speed and therefore direction of light as it changes medium and density. |
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How do you work out energy efficiency? |
Useful÷Total Efficiency |
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Describe evaporation using kinetic theory. |
When the fluid is heated, the fastest particles with the most energy escape first meaning the remaining particles have a lower average temperature. The fluid is now colder. |
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Why does steam condense when it hits a cold mirror? |
When the fluid particles hit the mirror, they lose energy and become more dense. When they've lost enough energy and become dense enough, the steam changes state to a liquid. |
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How do you work out payback time? |
Cost÷Annual Savings |
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What are the advantages and disadvantages of underground cables? |
They are out of the way Less likely to sustain damage
More expensive Hard to fix |
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What is a U-value? |
The amount of energy that can be transferred though something. |
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Explain how electricity is generated in a HEPP. |
Raised water is released though pipes where it falls to drive a set of turbines which powers a generator. |
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How is wave power used to generate electricity? |
A wave moves into an opening which force air into it. This drives a turbine that powers a generator that produces electricity. |
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What does the amount of energy an appliance transfers depend on? |
Its power and how long it is kept on for. |
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Describe redshift. |
As the source of the light moves away from you the waves spread out decreasing the frequency and increasing the wavelength making the source appear more red. |
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What are the units for energy? |
Joules |
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What are the units for time? |
Seconds |
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What does angle does light have to reflect at for T.I.R to work? |
Its critical angle. |
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What are the uses of gamma radiation? |
Sterilising medical equipment and treating cancer. |
