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P2
Fichas del conjunto (89)
- 1What are the 4 advantages of photocells?-Robust and don't need much maintenance
-Don't need fuel or power cables
-Don't cause pollution
-Use a renewable energy source - 2What is the only disadvantage of photocells?Don't produce electricity when it's dark or too cloudy
- 3What do photocells contain?Two pieces of silicon joined together to make a p-n junction
- 4Which has an impurity added to produce an excess of free electrons and which one has an impurity added to produce an absence of free electrons?n-type = excess
p-type = absence - 5What does sunlight contain?Photons
- 6What do photons cause?Free electrons to move, producing an electric current
- 7What are the 3 things that the output from a photocell depends on?-light intensity
-surface area exposed
-distance form light source - 8How does passive solar heating work?-Glass is transparent to suns short wavelength radiation
-Walls and floors absorb radiation, warm up then re-radiate infrared
-Re-radiated wavelength is longer as walls are not as hot as the sun
-Glass reflects the longer wavelength back into building - 9How are solar reflectors so efficient?Computer controlled so are always facing the sun
- 10When do wind turbines not work?Not enough wind/wind speed is too great
- 11What are the advantages and disadvantages of wind farms?+ don't contribute to global warming
+ don't pollute
- noisy
- take up lot of space
- can spoil view - 12What are the 3 ways in which the current from a dynamo can be increased?-Stronger magnet
-More turns on coil
-Rotating magnet faster - 13What does an oscilloscope do?Shows dynamo current change
- 14What is the time for one complete cycle called?Alternating current
- 15What does a simple generator consist of?Coil cuts through the magnetic field as it spins, a current is produced in the coil
- 16Where are the structure of simple generators used?In the generators at power stations
- 17How do conventional power stations work?Water boils to produce steam, steam at high pressure turns a turbine and the turbine drives a generator
- 18Why are power stations not very energy efficient?Lose energy through boilers, generators and cooling towers
- 19What type of radiation is absorbed by the earth's atmosphere?Infrared radiation
- 20What are the 5 things that produce carbon dioxide?-natural forest fires
-volcanic eruptions
-decay of dead plant and animal
-its escape from the oceans
-respiration - 21What are the 4 man made things that produce carbon dioxide?-Burning fossil fuels
-Waste incineration
-Deforestation
-Cement manufacture - 223 facts about water vapour-almost all of it occurs naturally
-0.001% comes from human activity
-half of the greenhouse effect is due to water vapour and a further quarter due to clouds - 23When is methane produced and give 2 examples of thisWhen organic matter decomposes in an environment lacking oxygen. Natural sources (wetlands, termites and oceans) and man-made sources (mining, burying of waste in landfills)
- 24Explain the greenhouse effectThe radiation from the sun is absorbed by the Earth, the earth re-radiates the energy as infrared radiation with a longer wavelength. These longer wavelengths are absorbed by the greenhouse gases which warms the atmosphere
- 25What does smoke from factories do?Reflect the radiation from the town back to Earth, causing the temperature to rise
- 26What does the ash cloud from volcanoes do?Reflects radiation from sun back into space, causing the temperature to fall
- 27What do scientists agree on to do with global warming?That the average temperature over the past 200 years has risen due to climate change
- 28What do scientists disagree on to do with global warming?The extent to which human activity has contributed
- 29When do we pay less for electricity?At night
- 30What are the 4 things that the choice of energy source depends on?-availability
-ease of extraction
-effect on the environment
-associated risks - 31What is the National grid?A series of transformers and power lines that transport electricity from the power station to the consumer
- 32What does the high voltage lead to? (3 things)-reduced energy loss
-reduced distribution costs
-cheaper electricity for consumers - 33What are used to step down the voltage to a more suitable level for the consumer?Transformers
- 34Why is a higher voltage used?Because this decreases the current to prevent energy loss (from heating the wires)
- 35What does ionisation involve?Gaining or losing electrons
- 36What can the formation of ions cause in the body?Chemical reactions such as strands of DNA to break or change; or protein molecules to change shape, possibly causing harm
- 37Where do alpha, beta and gamma radiations come from?The nucleus of an atom
- 38Which causes the most ionisation?Alpha
- 39What is alpha radiation's range and what does this cause to happen?A few centimetres so it is easily absorbed by a sheet of paper/card
- 40What is beta radiation's range and what does this cause to happen?About 1 metre and so is absorbed by a few millimetres of aliminium
- 41What is gamma radiation's range and what does this cause to happen?Much more penetrating and although a few cm of lead may stop some of the radiation, some can pass through several metres of lead or concrete
- 42How do smoke alarms use radiation to detect smoke?The alpha radiation ionises the oxygen and nitrogen atoms in the air causing a small current. When there is smoke the oxygen and nitrogen don't get ionised, causing the circuit to break and the alarm to go off
- 43How can radiation be used to control the thickness of paper?They use beta radiation and a detector, the amount of radiation passing through the sheet is monitored and the pressure on the rollers adjust accordingly
- 44What can gamma radiation be used for?Killing microbes and bacteria on medical equipment. It can be used to check for leaks in pipes and welds too.
- 45What can the passage of blood around the body be detected using?Beta and gamma radiation
- 46What is plutonium?A waste product from nuclear reactors which can be used to make nuclear bombs
- 47How do you dispose of low level and high level radioactive waste?Low level can just be buried in landfill but high level is encased in glass and buried deep underground.
- 48Why is the storage and disposal of radioactive waste very important?It remains radioactive for thousands of years and must be stored where it cannot leak into water supplies. It can be used by terrorists to contaminate water supplies too.
- 49What are the two advantages of using nuclear power stations?-Fossil fuels aren't used
-No greenhouse gases are made - 50What are the three disadvantages of using nuclear power stations?-High maintenance
-Decommissioning costs
-Risk of accidents are devastating - 51What types of orbits do comets have?Elliptical
- 52What are meteors made out of?Grains of dust that burn up as they pass through the earth's atmosphere. They heat the air around them which glows (a shooting star)
- 53What are black holes?Formed where large stars used to be. You can't see a black hole because light can't escape from it and it has a huge mass but is small in size
- 54Why do moons orbit planets?Because of the centripetal force acting on it
- 55What can we send up to explore space?Unmanned probes
- 56What do spacecraft carrying humans have to have a lot of?Food, water and oxygen
- 57What are the 4 things that an astronauts suit has to do?-a dark visor to stop them being blinded
-pressurised suit with oxygen supply
-the surface of the suit facing the sun has to be tolerant of temperatures up to 120 degrees
-the surface of the suit facing away from the sun has to be tolerant of temperatures up to -160 degrees - 58Why are unmanned spacecraft often better?Doesn't put astronauts lives at risk (but they have to be very reliable as they can't be repaired once in space)
- 59How fast does light travel?300,000km/s
- 60How long does light take to reach the earth from the sun?8 minutes
- 61How much does it cost to fly to Mars (according to America's planned trip)?£400 billion
- 62What are asteroids?Mini planets orbiting the sun left over from the formation of the solar system
- 63What caused all bodies in space to be created?When clouds of gas and dust collapsed together due to gravity
- 64What determines something's gravitational force?The mass
- 65What prevents asteroids from joining together to form another planet?Jupiter's gravitational force
- 66How do scientists think the moon was made?The collision of two planets. The iron core of one planet collided with the Earth's core then less dense rock began to orbit, forming the moon.
- 67What are the 3 pieces of evidence that support the theory of how the moon was created?-Avg. density of earth is 5500kg/m3 and the moon is 3300kg/m3
-There is no iron in the moon
-The moon has same oxygen composition as Earth (unlike other planets) - 68What are the 3 pieces of evidence that support the theory that asteroids have collided with the Earth?-near to crater they found quantities of the metal iridium (normally found in meteorites)
-many fossils are found below the layer of iridium (not many found above)
-tsunamis have disturbed fossil layers - 69Where do most comets pass?Inside the orbit of Mercury and well beyond the orbit of Pluto
- 70What happens as the comet passes close to the sun?The ice melts and solar winds blow the dust into the comets tail which always points away from the sun
- 71What are scientists constantly tracking?The paths of comets and other NEOs
- 72Why does the speed of a comet increase as it approaches the sun and decrease as it gets further away?Because of the changing gravitational attraction
- 73What shape is a comets orbit?Elliptical
- 74What happens if an NEO is heading for earth?A rocket may be exploded near it which should alter its course enough to miss the Earth
- 75In what way is the universe expanding?The galaxies are always moving away from each other and the furthest galaxies are moving the fastest
- 76How did Galileo's observations help support Copernicus' ideas?Galileo observed four moons orbiting Jupiter, supporting the theory that not everything orbits the earth, but the sun
- 77Why didn't the Roman Catholic Church support Galileo's model?Because it went against their ideas that the Earth was the centre of the universe
- 78What was Newton working on in the 17th century?His theory of universal gravitation, suggesting that all bodies attract one another
- 79Why do we believe that the gravitational collapse of the universe is prevented?As the universe is constantly expanding as a result of the Big Bang
- 80What is red shift?When a source of light is moving away from something, its wavelength appears to increase which shifts the light towards the red end of the spectrum
- 81What is the difference between the light pattern observed form the sun and from a distant star?The light from the star is closer to the red end of the spectrum
- 82What can scientists use red shift to find out?The age of the universe
- 83What is the swirling cloud of gas and dust?A nebula
- 84Explain a star's life-nebula cloud pulled together by gravity
-this protostar gets hot & glows
-gravity makes star get smaller hotter and brighter
-after millions of years it's so hot that nuclear fusion occurs
-hydrogen nuclei join to form helium nuclei
-energy is released and the star shines while there is enough hydrogen - 85Why do small stars shine for longer than large stars?They have less hydrogen but use it up at a slower rate
- 86How does a medium stars life end (like the sun)?Becomes a red giant: core contracts, outer part cools, changes from yellow to red and expands. Planetary nebula (gas shells) thrown out, core becomes white dwarf shining bright then becomes a black dwarf
- 87How does a large star's life end?Become red supergiant: core contracts, outer part expands, suddenly core collapses to form a neutron star - explosion (supernova).
- 88What can happen in the aftermath of a supernova?-neutron stars are very dense
-remnants can merge to form new star
-core of neutron star keeps collapsing, getting denser to form black hole - 89What are the properties of a black hole?-Large mass
-Small volume
-Very large density
-Large mass=strong gravitational pull
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- GCSE (P2) Physics Fichas sobre P2, creado por Anna Hollywood el 24/11/2013.
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- Anna Hollywood
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