A/A* Model Answers Physics P1

Transcription

1 A/A* Model Answers Physics P1 Name:...

2 Heat transfer Explain, in terms of particles, how heat is transferred through the glass wall of a boiling tube. (2 marks) particles vibrate with a bigger / stronger amplitude / faster / with me (kinetic) energy energy transferred by collisions with other particles accept particles vibrate me do not accept start to vibrate only do not accept answers in terms of free/mobile electrons Explain how heat is transferred by the process of convection from the gas flame at the bottom of the oven to the potatoes at the top of the oven. (3 marks) any three from: (air) particles / molecules / atoms gain energy (air) particles / molecules / atoms move faster (air) particles / molecules / atoms move apart air expands air becomes less dense warm/hot air rises do not accept heat rises If the potatoes need to be kept hot, they may be wrapped in shiny aluminium foil. Why does this help to keep the potatoes hot? (1 mark) (foil) reflects heat (back towards potato) (foil) is a po emitter (of heat radiation) The outside surface of a fridge-freezer is white and shiny. Give two reasons why this type of surface is suitable f a fridge-freezer. (2 marks) any two from: po absber of heat / radiation reflects heat / radiation (from room away from fridge-freezer ) reduces heat transfer into the fridge-freezer reduces power consumption of fridge-freezer

3 Explain why the vacuum between the glass walls of the flask reduces heat transfer by conduction and convection. (2 marks) because there are no particles in a vacuum conduction and convection need particles / medium Why is a layer of fleece good at reducing the transfer of heat from a skier s body? (1 mark) traps (small pockets of) air Explain, in terms of the particles in the metal, how heat is transferred through the radiat. (2 marks) free / mobile electrons gain (kinetic) energy free electrons collide with other (free) electrons / ions / atoms / particles A central heating system has several radiats joined together. The hot water goes from the boiler, through each radiat in turn and then back to the boiler f reheating. Give one reason, other than appearance, why it might not be a good idea to paint radiats black. (1 mark) any one from: transfer a lot of heat (too rapidly) water temperature drops too rapidly water too cold f the next radiat Why is the inside of a vacuum flask shiny? (1 mark) To reflect thermal energy back into the liquid. Use the kinetic they to explain why liquids can flow. (2 marks) Particles are not in a fixed position, so they can move past each other. Explain how a thermometer wks. (2 marks) When a thermometer is put into something hot, particles in liquid gain me energy, move me quickly, and so expand. The only place liquid can go is up the narrow tube. Opposite f when a thermometer is used to measure a cooler temperature. Describe what happens to the particles in a gas as the temperature increases. (2 marks) Particles gain me energy so they move faster and collide with each other me often. They take up me room. Explain how free electrons transfer heat in a metal. (2 marks) Metals contain free electrons which are free to move; free electrons can transfer thermal energy.

4 Why are liquids and gases po thermal conducts. (2 marks) The particles in a liquid are not in a regular arrangement, and in a gas they are too far apart. An ice cube is placed in a glass of water. In terms of energy and particles, explain why the water beneath the ice cube begins to sink. (2 marks) Convection. The particles in the water have less energy so move me slowly, increasing the density of the fluid, which causes it to sink. Describe how evapation can be used to keep things cool and give an example. (2 marks) By keeping them damp, thermal energy will be lost through evapation. Object needs to be left in the shade not in direct sunlight. Explain how a tumble dryer dries dark clothes. (2 marks) Increases rate of evapation by adding thermal energy and increasing flow of air. How could you reduce the rate of heat energy transfer from a hot drink? (2 marks) Put it in an insulated cup (which reduces heat transfer from conduction and convection) and put a lid on it (which reduces heat transfer by evapation). What can you say about the rate of heat energy transfer in an object that is at the same temperature as its surroundings? (2 marks) The rate of heat energy transferred into the object is the same as the rate of heat energy transferred out of the object. Why should you fill up a vacuum flask rather than half fill it? (1 mark) The rate of heat energy transferred into the object is the same as the rate of heat energy transferred out of the object. Wood has a high specific heat capacity. Why would you not use it in a heater? (2 marks) It is a po conduct of heat and it cannot transfer heat by convection radiation.

5 Electric kettles are found in most kitchens. Electric kettles are designed to transfer energy from electricity into heat. The energy is used to boil water. Most modern kettles have an automatic cut-off switch which turns the kettle off when all the water in it has boiled. Explain how the kettle boils all of the water befe it switches off. Use ideas about energy transfer by heating and kinetic they in your answer. (6 marks) Examples of scientific points made in the response: Resistance to electric current in element increases heat energy and / kinetic energy of particles. Increased collisions pass energy through element. Heat conducted into water from element. Water in contact with element gains heat / temperature rises; Becomes less dense; Particles further apart Water rises due to lower density. Cooler water falls and replaces warmer water in contact with the element. Warmer particles transfer energy to surroundings as rise ; Setting up convection currents. Water boils as all reaches same temperature.

6 Energy Explain why using an energy-efficient light bulb instead of an dinary light bulb reduces the amount of carbon dioxide emitted into the atmosphere. (2 marks) less electricity / energy to be generated / needed from power stations reduction in (fossil) fuels being burnt accept less demand accept crectly named fuel accept answer in terms of: fewer light bulbs required because they last longer (1 mark) less energy used / fuels burnt in production / transpt etc. (1 mark) igne reference to CO2 global warming igne reference to conservation of energy A student thinks that because energy cannot be destroyed it is not possible to waste energy. So he leaves his radio, TV and computer on all the time, even when there is no one in the house. Explain why he is wrong about not being able to waste energy. (2 marks) any two from: energy not usefully transfmed is wasted e.g. not listened to (wasted and useful) energy transferred to surroundings (energy spreads out) and is difficult to use usefully f further energy transfmations accept specific examples of energy wasted by any named appliances do not accept machines not 100 % efficient on its own What is meant by an energy source being renewable? (1 mark) will never run out do not accept can be used again What happens to the wasted energy? (1 mark) Gets dissipated transferred to surroundings / atmosphere becomes spread out Replacing an old freezer with a new A rated freezer will benefit the environment. Do you agree that replacing the freezer will benefit the environment? Answer yes no. Explain the reasons f your answer. (2 marks) yes plus explanation less electricity / energy needed / used less (fossil) fuels burned

7 less polluting gases emitted no plus explanation old freezer must be disposed of hazardous chemicals inside freezer (lot of) energy used in producing new freezer the marks are f the explanation accept less energy wasted accept a named fossil fuel do not accept conserving (fossil) fuels accept a named polluting gas / greenhouse gases / carbon emissions / reduce global warming accept an answer in terms of nuclear fuel eg less nuclear fuel required (1) less nuclear waste (1) accept CFC gases What happens to the energy wasted by the electric mot? (1 mark) transferred to surroundings / surrounding molecules / atmosphere becomes dissipated / spread out An A rated washing machine is me energy efficient than a C rated washing machine. Explain what being me energy efficient means. (2 marks) a smaller proption / percentage of the energy supplied is wasted accept a statement such as less energy is wasted f 1 mark do not accept costs less to run igne references to uses less energy Suggest why reducing the amount of energy used by washing machines could reduce the amount of carbon dioxide emitted into the atmosphere. (1 mark) any one from: less electricity needed fewer power stations needed less fuel is burned Any device that transfms energy will waste energy. Why must the total energy input to such a device always equal the total energy output from the device? (1 mark) energy cannot be destroyed accept energy is conserved

8 Generating Electricity What name is given to the netwk of cables and transfmers that links power stations to consumers? (1 mark) National grid What does a step-up transfmer do? (1 mark) increases voltage / potential difference accept decrease current accept step-up / boosts the voltage do not accept increases energy / power / current igne reference to voltage going through Explain why step-up transfmers are used in the electricity distribution system. (2 marks) any two from: reduce current igne increased voltage / pd reduces energy loss / power loss (from cables) increases efficiency (of distribution) accept reduces heat loss do not accept stops energy loss Most of the wld s electricity is generated in power stations that burn fossil fuels. State one environmental problem that burning fossil fuels produces. (1 mark) any one from: produces pollutant gases produces solid waste / ash / smoke accept produces carbon dioxide / sulfur dioxide / nitrogen oxides accept global warming / greenhouse effect / carbon emissions / air pollution / acid rain igne ozone layer do not accept carbon monoxide accept global dimming igne produces pollution What arguments could a company give to persuade people that a wind farm is a good idea? (2 marks) any two from: using renewable energy make non-renewable fuels last longer non-renewable fuels can be used f other processes no pollutant gases produced land can still be used f farming any two valid points gains the marks accept don t use up non-renewable / fossil fuels accept named fuels, igne no pollution, igne economic issues

9 What reasons may be given by the people who think that wind farms are not a good idea? (2 marks) any two from: cause noise pollution cause visual pollution may interfere with TV / radio / mobile phone signals need to put in new infrastructure not reliable owtte dangerous to birds lots of concrete needed f the bases producing cement is environmentally damaging accept spoils the landscape accept sunlight flicker accept new roads needed accept reduces house prices igne any references to cost / jobs / number required igne takes up a lot of land accept reference to obstruction of shipping etc. if clear reference to offshe wind farm Outline the arguments that a scientist wking in the nuclear power industry could use to justify the building of me nuclear power stations in the future. (3 marks) only accept answers in terms of the argument of the nuclear power scientist any three from: produces a lot of energy f a small mass of fuel is a concentrated energy source it is reliable it can generate all of the time produces no pollutant gases produces only a small volume of (solid) waste advances in technology will make fuel reserves last much longer accept amount f mass accept named gas greenhouse gases do not accept no pollution accept amount f volume accept an argument in terms of supply and demand Nuclear waste is a problem that must be dealt with. One possible solution would be to bury the waste deep underground. Suggest one reason why some people are against burying nuclear waste. (1 mark) may leak into the ground / environment geological changes may get into the food chain over time if location not crectly recded it may be excavated accept earthquakes etc, do not accept answers in terms of property prices damages the environment

10 Suggest why, apart from the declining reserves of fossil fuels, power companies should use me bio-fuels and less fossil fuels to generate electricity. (3 marks) any three from: carbon neutral so overall add no carbon dioxide to the environment power companies can sell electricity at a higher price opptunity to grow new type crop me jobs me land cultivated different types of land utilised accept do not add to global warming accept they are carbon neutral accept power companies make me profit accept specific examples e.g. growing plants in swamps accept extends the life of fossil fuel reserve Although there are some risks associated with nuclear power stations, it is likely that new ones will be built. Give two reasons to justify the use of nuclear power. (2 marks) any two from: produce no pollutant / harmful gases produces a lot of energy f a small mass (of fuel) is a concentrated energy source it is reliable it can generate all of the time produces only a small volume of (solid) waste answers should be in terms of nuclear power and not why we should not use other fuels accept named gas greenhouse gases do not accept no pollution accept amount f mass accept high energy density accept amount f volume Name the process by which a nuclear fuel provides the energy needed to generate electricity in a nuclear power station. (1 mark) Nuclear fission Transfmers are part of the National Grid. Transfmers are efficient devices. What is meant by a device being efficient? (1 mark) small proption of energy / power is wasted transfers most / me / a lot of energy power usefully accept little / less energy / power / heat is wasted do not accept it wastes no energy / power

11 When electricity flows through a cable, some energy is transfmed into heat. Explain how the National Grid system reduces the amount of energy lost as heat. (2 marks) it decreases the current / uses low current it increases the voltage / potential difference uses high voltage / potential difference smaller the current the smaller the energy loss Explain why leaving appliances on standby damages the environment.(2 marks) any two from: (me) electricity needs to be generated (me) power stations needed (me) fossil fuels burnt (me) pollutant gases emitted Explain how the heat released from a nuclear fuel is used to generate electricity in power stations. (2 marks) water heated to produce (high pressure) steam steam turns turbine which drives generat Nuclear power stations create dangerous waste. Why is the waste from a nuclear power station dangerous? (1 mark) it is / can be radioactive emits radiation (from the nuclei) do not accept answers in terms of kills cells / cancer Explain the possible link between climate change and coal-burning power stations. (2 marks) coal (burning) power stations / burning coal produces carbon dioxide (increased) CO2 increases / contributes to / causes global warming / greenhouse effect Explain how the step-up transfmer increases the efficiency of the National Grid. (2 marks) decreases the current reducing energy loss (along cables)

12 The electricity used in homes in the UK is nmally generated in a fossil fuel power station. Outline some of the advantages of using solar cells to generate this electricity. (2 marks) produce no / less (air) pollution energy is free (energy) is renewable conserves fossil fuel stocks can be used in remote areas do not need to connect to the National Grid The power output from a conventional large-scale hydroelectric power station is times me than the power output from a microhydroelectric system. Give one disadvantage of a conventional large-scale hydroelectric power station compared to the micro-hydroelectric system. (1 mark) any one from: large areas of land are flooded peoples homes may be destroyed habitat (of animals and plants) lost / damaged Explain why transferring the electricity directly to local homes is me efficient than using the National Grid to distribute the electricity. (2 marks) less energy loss / wasted (in the cables) as the cables are shter What are the differences between a conventional power station and a geothermal power station? (2 marks) Different sources of thermal energy to heat water to turn it into steam to drive the turbines. In some geothermal power stations, steam from under the ground can be used to drive turbines directly. Conventional uses coal, oil natural gas. What is the function of the cooling towers? (1 mark) To condense steam back into water. Why is it imptant that natural gas power plants have a sht start up time? (1 mark) To provide extra electricity if there is a sudden increase in demand.

13 Explain the process of carbon capture and give an example of where carbon dioxide might be sted. (2 marks) The CO2 produced by burning fossil fuels is not released into the atmosphere. Instead, it is captured and sted. Examples of stage sites include old oil and gas fields. List some of the disadvantages of using fossil fuels to generate electricity. (3 marks) Burning fossil fuels releases CO2 into the atmosphere ( other named fm of atmospheric pollution). Fuels need to be mined/extracted and then transpted to power stations. Visual pollution. Is nuclear power a renewable non renewable energy resource? Explain your answer. (2 marks) Non-renewable we will eventually run out of uranium (although this will happen a long time in the future). State the energy changes inside a nuclear power plant (ending with electrical energy from the generat) (2 marks) Nuclear energy heat ( thermal) kinetic electrical Describe how nuclear reacts can be used to generate electricity. (2 marks) A nuclear reaction produces heat. This heat turns water to steam. The steam turns a turbine which turns a generat which generates electricity. Describe the similarities and differences between biofuels and fossil fuels. (4 marks) Similarities: both involve burning fuel derived from living ganisms; both can be used to generate electricity (and the process is very similar). Differences: the ganisms which fmed fossil fuels died millions of years ago; fossil fuels are generally a me concentrated fm of chemical energy; biomass is carbon neutral; biomass is a renewable energy resource. Explain why biomass is described as carbon neutral. (2 marks) There is no increase of CO 2 in the atmosphere. Burning biomass only releases the CO 2 that the plant absbed when it was growing. Solar cells are used to provide electricity f garden lights. What is needed so that the lights can come on at night? (1 mark) Something to ste the energy/ such as a cell/battery

14 Why is electricity stepped up befe being distributed by the national grid? (1 mark) Energy losses from the high current would be much bigger; the cable would burn out. Why is electricity stepped down befe it enters the home? (2 marks) So it is safe to use; electrical devices are designed to be used at 230 V. The picture shows one type of solar water heater. Water from the tank is slowly pumped through copper pipes inside the solar panel where the water is heated by energy from the Sun. The water in the tank could be heated by using an electric immersion heater. Outline the advantages and the disadvantages of using solar energy to heat the water rather than using an electric immersion heater. (6 marks) Advantages: Renewable energy source Energy is free Does not pollute the atmosphere No fuel is burnt Energy can be sted in water Disadvantages: Only available in daylight Availability fluctuates Insufficient hours of sunlight in some countries Average low intensity in some countries Over the next 10 years, me than 300 kilometres of new high voltage transmission cables are to be added to the National Grid. Most of the new cables will be suspended from pylons and run overhead while the rest will be buried underground. Outline the advantages and disadvantages of both overhead transmission cables and underground transmission cables. (6 marks) Overhead advantages: - quick/easy to repair/access - less expensive to install/repair/maintain -cables cooled by air - air acts as insulat - can use thinner cables Overhead disadvantages - spoil the landscape - greater risk of electric shock - damaged/affected by severe weather - hazard to low flying aircraft/helicopters

15 Underground advantages: - cannot be seen - no hazard to aircraft/helicopters - unlikely to be damaged by severe weather - reduced shock hazard Underground disadvantages: - repairs take longer/me expensive - me difficult to access - very expensive to install - thicker cables required - need cooling systems - need layers of electrical insulation - land disruption

16 Waves What is gamma radiation? (1 mark) electromagnetic (wave / radiation) A student listens to the sound waves produced by a car siren. When the car is stationary, the student hears a constant frequency sound. Describe how the wavelength and frequency of the sound waves heard by the student change when the car is driven away from the student. (2 marks) wavelength increases accept the crests are further apart igne waves are further apart frequency decreases accept pitch decreases igne references to amplitude Explain why living near a mobile phone mast could cause ill health. (3 marks) emit / uses / transmit / receive microwaves some microwave / energy absbed by / enters the body raises temperature of (body) cells / tissue / water any mention of alpha, beta, gamma waves sces 0 marks accept radiation f microwaves throughout igne radio waves ecf f their given electromagnetic wave do not accept goes through the body accept reference to water molecules vibrating faster accept it could cause mutation / harm / kill cells do not accept answers in terms of ionisation igne references to cancer A person has naturally dark skin. Suggest why he can sunbathe with less risk of getting skin cancer than a fair- skinned person. (2 marks) me UV / radiation absbed by dark skin less UV penetrates deep to damage (living) cells / tissue accept darker skin has me melanin / pigment do not accept sunlight heat f ultraviolet Most people know that sunbathing can cause skin cancer. But most holidaymakers still like to come home with a suntan. Why is it imptant that people understand that there are dangers involved in sunbathing? (1 mark) so people can make up their minds about the potential risk to their health. accept so people know to take precautions

17 Visible light travels through air at m/s. Why can we assume that radio waves travel through air at the same speed as light? all electromagnetic waves travel at the same speed through a vacuum, (so assume same speed in air) Who is likely to be exposed to me ultraviolet radiation, a skier a golfer? Draw a ring around your answer. A skier a golfer Give a reason f your answer. (2 marks) skier exposed to high(er) level reflected UV less UV absbed by the atmosphere golfer out when Suniś intensity is highest larger area of skin / body exposed accept radiation f UV accept snow is a good reflect of UV do not accept snow reflects UV accept snow is a po absber of UV do not accept snow absbs UV accept when Sun is stronger / hotter accept golfer is outside f longer Some scientists think that there is a link between using a mobile phone and some types of illness. Other scientists disagree. They say that the evidence is limited and unreliable. Suggest what scientists could do to show a link between using a mobile phone and illness. (1 mark) compare (the health of) mobile phone users with non-mobile phone users How could scientists improve the reliability of the evidence? (1 mark) Repeat/increase sample size Devices designed to protect a mobile phone user from microwave radiation are now available. Why is it imptant that these devices are tested by scientists who are not wking f the company that makes the devices? (1 mark) any one from: to get an independent opinion company scientists may be biased What is meant by the term radioactive? (1 mark) substances that give out radiation Which type of electromagnetic wave has a lower frequency than microwaves? (1 mark) Radio waves

18 What do all types of electromagnetic wave transfer from one place to another? (1 mark) Energy Microwaves and visible light are two types of electromagnetic wave. Both can be used f communications. Give two properties that are common to both visible light and microwaves. (2 marks) any two from: travel at the same speed (through a vacuum) can travel through a vacuum / space transfer energy can be reflected can be refracted can be diffracted can be absbed can be transmitted transverse Name two me types of electromagnetic wave that can be used f communications. (2 marks) infra red radio(waves) What type of wave is used to send infmation to and from satellites? (1 mark) Microwaves What property of this type of wave makes it suitable f satellite communications? (1 mark) Can pass through ionosphere In 2009, parts of the African country Kenya, were linked to the Internet by a super-fast optical fibre. Befe that, all Internet connections had to be made via a satellite link. Complete the following sentence. Signals can be sent along an optical fibre using either visible light Microwaves Microwaves and radio waves are both part of the electromagnetic spectrum. How are microwaves different from radio waves? (1 mark) higher frequency shter wavelength greater energy How fast do microwaves travel through the air a vacuum compared to radio waves? (1 mark) Same speed

19 As the loudspeaker moves towards the students, the frequency of the note heard by the students increases. What happens to the note heard by the students as the loudspeaker moves away from them? (1 mark) frequency / pitch decreases accept wavelength increases accept it Describe how a string could be used to demonstrate transverse and longitudinal waves. (2 marks) Vibrate one end of the spring (the other end should be fixed). Moving the vibrating end in the same direction as the spring, creates a longitudinal wave. Moving the end at 90 to the spring creates a transverse wave. Describe how a speaker produces compressions and rarefactions. (2 marks) The cone moves in and out. When it moves out, it creates a compression; when it moves back in, it creates a rarefaction. Explain why in some valleys you can t get a TV signal but you can pick up longer wavelength radio signals. (2 marks) The longer the wavelength the greater the diffraction. Radio waves have a longer wavelength than TV waves and so when they travel around obstacles (like hills); they diffract me. This allows the signal to reach the bottom of some valleys. TV signals have a shter wavelength and so they do not diffract as much; the signal does not reach all parts of the valley. Why are X-rays potentially hazardous and what measures, can be taken to reduce the risks when using them? (2 marks) They have a sht wavelength (high frequency); this means they can transfer a lot of energy and they are very penetrating. To reduce the risks from X-rays you could limit your exposure time wear shielding (lead-lined apron). Explain why TV signals are generally a shter wave length than radio signals? (2 marks) Me infmation needs to be sent in a TV signal (pictures and sound). Therefe shter wavelengths are used. Describe what causes the Doppler effect. (2 marks) When the wave source moves towards a listener/receiver the waves are bunched up. This causes an increase in frequency/decrease in wavelength. When the wave source moves away from the listener/receiver the opposite happens. Explain what would happen to the change in pitch if the F1 car was moving much faster. (2 marks) It would be me noticeable; the sound would be of much higher pitch as the car moved towards the observer, and much lower pitch as it moved away.

20 Earth Satellites fitted with various telescopes bit the Earth. These telescopes detect different types of electromagnetic radiation. Why are telescopes that detect different types of electromagnetic waves used to observe the Universe? (1 mark) stars / galaxies / sources emit all / accept two me named different types of electromagnetic waves / electromagnetic waves radiation accept answers in terms of frequencies / wavelengths In 2005 a space telescope detected a star that exploded 13 billion years ago. The light from the star shows the biggest red-shift ever measured. What is red-shift? (1 mark) wavelength (of light) increases accept frequency decreases light moves to red end of spectrum accept redder but do not accept red alone What does the measurement of its red-shift tell scientists about this star? (1 mark) it is the star (detected) furthest from the Earth it is moving away the fastest Red-shift provides evidence f the big bang they. Describe the big bang they. (2 marks) all matter compressed to / starts at / comes from a single point (massive) explosion sends matter outwards do not accept increasing gravitational pull accept everything / the universe f all matter accept explosion causes universe to expand igne explosion creates the universe further reference to star / Earth fmation Suggest what scientists should do if new evidence were found that did not suppt the big bang they. (1 mark) check validity / reliability of the evidence change the they to match the new accept comparison of new and old evidence evidence

21 Explain how the spectrum shift of the dark line suppts the they that the Universe began from a very small point. (3 marks) line shifts towards red end of spectrum wavelength (appears) to increase galaxy is moving away (from the Earth) galaxy moving away from initial point do not accept reference to e red lighti do not accept e red shifti as a stand alone response do not accept universe expanding do not accept planet on its own The steady state they was once a popular alternative to the big bang they. The steady state they suggested that the universe, although expanding, had no igin and it has always existed. As the universe expands, a small amount of matter is created to keep the universe looking exactly the same all of the time. (a) When considering the igin of the universe, what is the difference between the big bang they and the steady state they? big bang they - universe started at one point (then expanded) steady state they - universe has no igin / has always existed The light from distant galaxies shows a red-shift. What is red-shift? (1 mark) wavelength (of light) increases wavelength / light moves to red end of spectrum accept answers in terms of frequency decrease accept wavelength stretched but not wave stretched do not accept galaxy moves to the red end of the spectrum do not accept light becomes red / redder Why does red-shift provide evidence to suppt both the big-bang they and the steady state they? (2 marks) red-shift is evidence / suppts idea of expanding universe both theies use the idea / accept / explain why the universe is expanding The steady state they was imptant in encouraging new research into the universe. Suggest a reason why scientists were keen to carry out new research. (1 mark) to find evidence to suppt one both theies to find evidence to disprove one both theies accept prove f suppt accept to gain me knowledge about the universe

22 Scientists can answer many questions about the universe, but not the question: Why was the universe created? Suggest a reason why this question cannot be answered by scientists. (1 mark) answer involves (religious) belief accept it cannot be tested no / insufficient evidence The Big Bang they is one they of the igin of the Universe. Explain what is meant by the Big Bang they. (2 marks) Universe began at a (very) small (initial) point explosion sent matter outwards explosion causing Universe to expand The light arriving from distant galaxies provides scientists with evidence to suppt the Big Bang they. Explain how. (2 marks) light shows a red shift galaxies moving away (from the Earth) At a meeting held in 2005, a group of scientists claimed that new data had been collected that showed the Big Bang they to be wrong. Other scientists said that there was no reason to doubt the Big Bang they. What should scientists do when a they does not appear to be suppted by new data? (2 marks) check reliability / validity of data amend they discount the data accept check data accept collect me data accept replace old they with new they The Ancient Greeks believed that the Universe went on fever ; it never changed and had no beginning. It had always existed. How are the ideas put fward by the big bang they different from the beliefs of the Ancient Greeks? (2 marks) Universe had a start point Universe is (still) changing / expanding

23 Describe what scientists have noticed about the red shift from galaxies further away from us and explain what this means about those galaxies. (2 marks) The red-shift is greater; this means the galaxy is moving away faster. What would happen to the light observed from a galaxy that was moving towards us? Suggest a name f this effect. (2 marks) Light from galaxies moving towards us would be compressed (its wavelength would decrease). This might be called blue- violet-shift. Explain the igin of cosmic background radiation. (2 marks) The heat left over from the Big Bang. As the Universe has expanded it has cooled, and this heat is in the microwave region of the electromagnetic spectrum. Explain why the Big Bang they is at present the most widely accepted they on the igin of the Universe. (1 mark) It is the only they that explains the igin of cosmic microwave background radiation. How is the red shift used to suppt the Big Bang they? (2 marks) Further away galaxies are moving fastest; this suggests that the Universe is expanding. Current evidence suggests that the universe is expanding. Most scientists currently believe that the universe began with a huge explosion called the Big Bang. Describe how observed evidence suppts this they. (6 marks) Examples of scientific points made in the response: If a wave is moving relative to the observer there will be a change in the observed wavelength And/ frequency Increase in wavelength of light from distant galaxies Further away the galaxy, the faster it is moving And bigger observed increase in wavelength This is called red shift Observed red shift suppts big bang they