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  • Created by: apple87
  • Created on: 04-06-14 11:36
How is wind created?
Warm air heated by the sun rises then cold air comes in to take its place.
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What affect the output of a photo cell?
Surface area, light intensity, distance from light source
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What are the advantages of photo cells?
Sturdy, low maintenance, last a long time, renewable energy source, doesn't pollute the environment
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How do photo cells generate electricity?
Silicon atom absorb the energy which knocks free some of the electrons. The electrons flow around the circuit creating elecricity.
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Does glass let through long or short wavelengths?
Short
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What type of radiation is emitted by objects that have been heated up?
Infrared radiation which is a longer wave length
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What the the advantages of wind turbines?
Cheap to run, tough and reliable, wind is free, no polluting waste produced, renewable energy source.
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What are the disadvantages of wind farms?
Need around 1500 turbines to replace one coal power station, noise and visual pollution, no wind=no power, impossible to increase supply, expensive to set up, hard to find a wind and large enough space to build the turbines.
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How is electricity generated?
Fuel is burned to turn water into steam, steam turns a turbine which then turns a generator which produces electricity.
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What are the advantages and disadvantages of biomass?
Advantages- renewable, carbon neutral, don't need to import Disadvantages- Takes lots of space to grow and need a lot of biomass to replace one lump of coal
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What is electromagnetic induction?
The creation of a voltage in a wire which is experiencing a change in magnetic field
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How do you get a bigger current and voltage in an electromagnet?
Increase strength of the magnet, increase the number of turns on the coil, increase the speed of movement
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If the direction of movement is reversed then the voltage/current will...
reverse to
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Every half turn the crrent in the coil swaps...
direction
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What type of currect to generator produce?
Alternating current (AC)
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Why is electricity not transmitted at a high current?
The cables get very hot so lots of energy is wasted as heat
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What is a Kilowatt hour?
The amount of electrical energy converted by a 1kW appliance left on for one hour
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What are the advantages of off peak electricity?
Cost effective for the company as power stations can't be turned off. Cheaper for consumers
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What are the disadvantages of using off peak electricity?
Increased fire risk with more appliances going at night and no one watching. You start fitting your routine around the cheap rate hours eg you might stop enjoying the use of electricity during the day.
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How does carbon dioxide inrease the amount of green house gases?
People use more energy mainly from burining fossil fuels. More land is needed so deforestation occurs. CO2 comes from respiration
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How does methane increase the amount of greenhouse gases?
Cattle farming has increased to feed the growing population- cattle digestion produces methane. Decaying waste in landfill produces methane. MEthane is naturally released from volcanoes wetlands and animals.
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Describe the greenhouse effect.
1) Energy from the sun is absorbed by the Earth. 2) The Earth radiates heat... 3) Which is absorbed by greenhouses gases... 4) ...and re radiated in all directions.
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What are the human causes for climate change?
Rising CO2 levels and soot produced by factories which can reflect heat back to Earth.
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What are the natural causes for climate change?
Ash and gases released by volcanoes can cause radiation from the sun to reflected back into space. Changes in out orbit around the sun can cause ice ages.
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What properties do alpha particles have?
Relatively big and heavy ans low moving. Because of their size they are stopped quickly. They strongly ionise
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What properties do beta particles have?
They are electrons so they are small and move quite fast. They penetrate further than alpha. They are moderately ionising.
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What properties do gamma rays have?
Very high frequency electromagnetic waves. Have no mass or charge. Penetrate a long way. Weakly ionising
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What can radiation do to human body cells?
It can ionise molecules and damage DNA. This can cause mutation and lead to cancer.
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What type of radiation do smoke detectors use?
Alpha
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How do smoke detectors work?
They have a weak source of alpha radiation close to two electrodes. The radiation ionises the air and the current flows between the two electrodes. Smoke absorbs the radiation causing the current to stop and the alarm sounds.
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What medical uses does beta radiation have?
Tracers and thickness gauges
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What are the medical and industrial uses of gamma radiation?
It can kill cancer cells. Sterilise medical instruments. For non-destructive testing airlines use it to detect cracks in turbine blades.
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How does a nuclear power station work?
Nuclear fission produces the steam. Nuclear fission the atoms in the nuclear fuel are split in two releasng lots of heat energy. Water is used as a coolant to take the heat away steam is produced which drives a turbine and a generator.
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What are the advantages of nuclear power?
Doesn't release CO2, releases more energy than fossil fuels, nuclear fuel is relatively cheap, pleantly of uranium left in the ground.
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What are the disadvantages of nuclear power?
Expensive to build and maintain, takes longer to start up station, processing Uranium causes pollution, risk for radioactive eaks, radioactive waste needs to be disposed of, expensive to decommission, uranium is non-renewable
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What can plutonium be used for?
Nuclear bombs
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How should you protect yourselfe from nuclear radiation?
Don't do anything stupid like eating a smoke alarm. Store radioactive sources safely in a lead box. Keep your exposure time as short as possible. Handle sources with tong, never allow skin contact. Keep the source at arms length, don't look directly
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How are workers protected from uclear radiation?
Wear full protective suits to prevent tiny particles being inhaled. Lead lines suits, lead barriers and screens sheild workers from gamma rays. Workers use robots to carry out tasks in highly radioactive areas.
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What are the problems with disposing of radioactive waste?
Site has to be geolographically stable, could be buried deep underground, NIMBY attitude, terrorists could steal radioactive waste.
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What is classed as low level radioactve waste?
Most waste from nuclear power stations and hospitals like paper, clothing, gloves, syringes
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How is highly radioactive waste disposed of?
Sealed in glass blocks which is then sealed in metal container. It could then be burried underground for tens of thousands of years.
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What sort of force causes circular motion?
Centripetal force
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How is circular motion caused?
By the force towards the centre of the circle. For planets and moons this force is provided by gravity
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What are meteorites?
Rocks that have crashed on Earth.
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What are the effects of meteorites?
Start fires, throw loads of rock and dust into the air. The dust blocks out the sunlight causing climate change.
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What tyoe of orbit to comets use?
Elliptical
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What are comets?
Balls of rock, dust and ice
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What happens as a comet approaches the sun?
The ice melts leaving a tail of gas and debri which can be millions of kilometers long.
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What is a light year?
The distance light travels through a vacum in one year
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What are the problems with sending a manned space craft to Mars?
Difficult to keep astronauts alive- need lots of food, oxygen, water. Remove toxic gases, need to sheild from radiation, long exposure to gravity causes muscle wastage and loss of bone tissue, psychologically stressful.
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What are the advantages of unmanned probes?
Don't need food, water or Oxygen. Can withstand conditions humans can't, people. Cheaper- less is spent of safety. If something goes wrong no one is hurt.
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What are the disadvantages of unmanned probes?
Con't think for themselves- they can't overcome simple problems. Can't do maintenance and repairs.
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Describe the life cycle of a small star?
Cloud of dust and gas gather due to gravity. Protostar, mainsequence star, red giant, planetary nebula, white dwarf
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Describe the life cycle of a large star?
Cloud of dust and gas gather due to gravity. Protostar, mainsequence star, red giant, supernova, neutron star or black hole
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What was the Ptolemaic model?
Greek atronomer belived the Sun, Moon, Stars orbited the Earth in perfect circles,
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What was the Copernican model?
Galileo discovered the sun is at the centre
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Other cards in this set

Card 2

Front

What affect the output of a photo cell?

Back

Surface area, light intensity, distance from light source

Card 3

Front

What are the advantages of photo cells?

Back

Preview of the front of card 3

Card 4

Front

How do photo cells generate electricity?

Back

Preview of the front of card 4

Card 5

Front

Does glass let through long or short wavelengths?

Back

Preview of the front of card 5
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