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Name 5 advantages of photocells.
ANY 5 FROM: Robust/don't need much maintenance/need no fuel/don't need long power cables/cause no pollution/don't contribute to global warming/use a renewable energy resource
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Name one disadvantage of photocells.
The only disadvantage is that they do not produce electricity when it is dark or too cloudy.
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A photocell contains 2 pieces of silicon joined together to make a p-n junction. The n-type silicon has an impurity added to it - what does this do?
It produces an excess of free electrons.
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A photocell contains 2 pieces of silicon joined together to make a p-n junction. The p-type silicon has a different impurity added to it - what does this do?
It produces an absence of free electrons.
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Sunlight contains energy packets called photons. Photons cause ........... ............ to move producing an ............. .............
free electrons, electric current
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What does the output from a photocell depend on? (3 factors)
The light intensity, the surface area exposed and the distance from the light source.
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The Sun is very hot and produces ................ ................. with a very short ......................
infrared radiation, wavelength
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Passive solar heating uses glass to help keep buildings warm. Describe this process.
Glass transparent to the short wavelength radiation from the Sun; the walls and floor inside a building absorb this radiation, warm up and re-radiate it.....walls/floor not as hot as Sun so wavelength longer, glass reflects it (building).
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What are solar reflectors moved by to make sure they are always facing the Sun?
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Give 2 advantages and 2 disadvantages of wind farms.
Advantages: Do not contribute to global warming or pollute the atmosphere. Disadvantages: Noisy/spacious/'spoil the view' (any 2)
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What can you do to increase the current from a dynamo? (Give 2 examples)
Use a stronger magnet/increase the number of turns on the coil/rotate the magnet faster
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What can the output from a dynamo be displayed on? What does this show?
An oscilloscope - an oscilloscope trace shows how the current produced by the dynamo varies with time.
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What is alternating current?
The current produced by the dynamo varies with time. The time for one complete cycle is called the period of alternating current.
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A simple generator (AC generator) consists of what? How does it work?
Consists of a coil of wire rotating between the poles of a magnet. The coil cuts through the magnetic field as it spins and a current is then produced in the coil.
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In conventional power stations, fuels are used to heat water. How?
1) water boils to produce steam, 2) steam at high pressure turns a turbine, 3) the turbine drives a generator
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What is efficiency a measure of? How is energy in a power station lost? (3 factors)
Efficiency is a measure of how well a device transfers energy. Energy in a power station is lost in the boilers, generator and cooling towers.
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Carbon dioxide occurs naturally in the atmosphere as a result of what? (Name 3 factors)
Natural forest fires/volcanic eruptions/decay of dead plant and animal matter/its escape from the oceans/respiration
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What is man-made carbon dioxide caused by? (Name 3 factors)
Burning fossil fuels/waste incineration/deforestation/cement manufacture
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Methane is produced when organic matter decomposes in an environment lacking oxygen. Name 2 natural sources and 1 man-made source.
Natural: wetlands/termites/oceans. Man-made: mining and burning of fossil fuels/burying of waste in landfills.
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The greenhouse effect is similar to passive solar heating, but the Sun's radiation is re-radiated by the Earth. What is the longer wavelength radiation absorbed by?
Absorbed by the greenhouse gases which warms the atmosphere.
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What are dust warms?
The smoke from the factories reflects radiation from the town back to Earth. The temperature rises as a result.
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What are dust cools?
The ash cloud from a volcano reflects radiation from the Sun back into space. The temperature falls as a result.
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Some energy sources are more appropriate than others in a particular situation. What factors do the choice of energy sources depend on? (Name 2 factors)
Availability/ease of extraction/effect on the environment/associated risks
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The National Grid is a series of transformers and power lines that transport electricity from the power station to the consumer. Transformers are used to increase voltage to as high as 400,000V. What does this high voltage lead to?
Reduced energy loss, reduced distribution costs and cheaper electricity for consumers.
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When a current passes through a wire the wire gets hot. The greater the current, the hotter the wire. When a transformer increases the voltage, what happens to the current? What does this mean?
The current is reduced, which means there is less heating effect and therefore less energy lost to the environment.
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The formation of ions can cause chemical reactions. Such reactions may disrupt the normal behaviour of molecules inside the body which is potentially harmful. Give 2 examples of what these reactions could cause.....
1) They may cause strands of DNA to break or change; 2) protein molecules may change their shape
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Where do alpha, beta and gamma radiations come from?
The nucleus of an atom.
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Alpha radiation causes most ionisation and gamma radiation the least. Alpha radiation is short ranged (a few centimetres) - what is it absorbed by?
It is easily absorbed by a sheet of paper or card.
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Beta radiation has a range of about 1 metre - what is it absorbed by?
It is absorbed by a few millimetres of aluminium.
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Gamma radiation is much more penetrating - what will stop most of the radiation? What is the other problem related to this?
A few centimetres of lead will stop most of the radiation, but some can pass through several metres of lead or concrete.
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Experiments can be done to identify each type of radiation from its penetrating power - what should always be taken into account when carrying out these experiments?
Background radiation
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Smoke alarms contain a source of alpha radiation. How do they work?
The radiation ionises the oxygen and nitrogen atoms in the air which causes a very small electric current that is detected. When smoke fills the detector in the alarm during a fire, the air is not so ionised, the current is less and the alarm sounds.
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What can be controlled using a source of beta radiation and a detector? How?
Thicknesses in a paper rolling mill - the amount of radiation passing through the sheet is monitored and the pressure on the rollers is adjusted accordingly.
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What does gamma radiation kill? Therefore, what can it be used for?
Kills microbes and bacteria so can be used for sterilising medical instruments. It can also be used to check for leaks in pipes and welds.
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The passage of blood and other substances can be traced around the body using a ......... or ......... source.
beta, gamma
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What is the waste product from nuclear reactors which can be used to make nuclear bombs?
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Some low level radioactive waste can be buried in landfill sites. What happens to high level waste? How must it be stored?
High level waste is encased in glass and buried deep underground or reprocessed. Radioactive waste can remain radioactive for thousands of years; must be stored where it cannot leak into natural underground water supplies and hence into lakes/rivers.
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Name 2 advantages of nuclear power stations and 2 disadvantages.
Advantages: fossil fuel reserves are not used/no greenhouse gases discharged into atmosphere. Disadvantages: very high maintenance, decommissioning costs/risk of accidents (e.g.Chernobyl).
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What is a meteor made up of? What do they do to the air around them?
A meteor is made from grains of dust that burn up as they pass through the Earth's atmosphere. They heat the air around them which glows - the streak is known as a 'shooting star'.
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Moons orbit planets and planets orbit stars because centripetal force acts on them. Describe this in more detail, including the term 'gravitational attraction'.
Centripetal force acts towards the centre of the circular orbit; gravitational attraction is the source of the centripetal force.
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Outside a spacecraft, astronauts need to wear special spacesuits. Give 4 factors in relation to this suit.
A dark visor stops an astronaut being blinded/suit is pressurised with oxygen supply for breathing/surface of suit facing the Sun can reach 120 degrees C/surface facing away from the Sun can be as cold as -160 degrees C.
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Give 2 advantages of unmanned spacecraft and explain why they have to be very reliable.
Cost less/do not put astronauts' lives at risk - but have to be very reliable because there is usually no way of repairing them when they break down.
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How were all bodies in space, including planets, formed?
Clouds of gas and dust collapsed together due to gravitational forces of attraction.
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The mass of an object determines its gravitational force. Asteroids have relatively low masses compared to the mass of Jupiter. What does Jupiter's gravitational force prevent?
It prevents asteroids from joining together to form another planet.
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Explain IN DETAIL what scientists believe our Moon was a result of (in terms of collisions between two planets in the same orbit).
It was a result of the collision between 2 planets in the same orbit. The IRON CORE of the other planet melted and joined with the Earth's core, LESS DENSE rocks began to orbit and they joined together to form our Moon.
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There is scientific evidence that supports the idea of the Moon being formed in the way scientists believe it was. What are these 3 pieces of evidence?
1) The average density of the Earth is higher than that of the Moon (5500 kg/m3 compared to 3300kg/m3), 2) there is no iron on the Moon, 3) Moon has exactly the same oxygen composition as the Earth, but rocks on Mars or meteorites are different.
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Geologists examine evidence to support the theory that asteroids have collided with Earth. Give 3 pieces of evidence in relation to this.
1) Near to a crater presumably as a result of asteroid impact, they found quantities of the metal iridium (not normally found on Earth's crust but common in meteorites), 2) many fossils found below iridium layer but few found above it, 3) tsunamis
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What did Galileo observe using the newly invented telescope? Who's idea did this support and why? Which Church did not support Galileo's model?
Galileo observed 4 moons orbiting Jupiter. This supported Copernicus' idea that planets orbit the Sun and confirmed that not everything orbited the Earth. Roman Catholic Church did not support Galileo's model (believed Earth at centre of Universe).
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What was Newton's theory? What did it suggest?
Theory of universal gravitation which suggested that all bodies attract one another.
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What is red shift?
When a source of light is moving away from an observer, its wavelength appears to increase which shifts light towards the red end of the spectrum.
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What is a nebula? What are nebula clouds pulled together by? Why can the protostar not be seen? After millions of years, the core temperature is hot enough for what to take place?
A swirling cloud of gas and dust/gravity/cannot be seen because of the dust cloud/hot enough for nuclear fusion to take place
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A black hole has a very large ....... concentrated in a small ........ so it has a very large .......... and its large mass means it has a very strong .................. ...........
mass, volume, density, gravitational pull
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Other cards in this set

Card 2


Name one disadvantage of photocells.


The only disadvantage is that they do not produce electricity when it is dark or too cloudy.

Card 3


A photocell contains 2 pieces of silicon joined together to make a p-n junction. The n-type silicon has an impurity added to it - what does this do?


Preview of the front of card 3

Card 4


A photocell contains 2 pieces of silicon joined together to make a p-n junction. The p-type silicon has a different impurity added to it - what does this do?


Preview of the front of card 4

Card 5


Sunlight contains energy packets called photons. Photons cause ........... ............ to move producing an ............. .............


Preview of the front of card 5
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