P2 Learning Outcome Questions

Transcription

1 Question Answer State 4 facts about photocells. Recall that DC electricity is current in the same direction all the time. Describe how the Sun s energy can be harnessed. Describe some advantages and disadvantages of using photocells to produce electricity. Describe how light produces electricity in a photocell. What factors affect the current and power produced by a photocell? disadvantages of wind turbines. Explain why passive solar heating works. transfer light into electricity produce direct current (DC) can operate in remote locations have a power or current that depends on the surface area exposed to sunlight radiation from the Sun can be absorbed by a surface and transferred into heat energy produce convection currents (wind) to drive turbines how glass can be used to provide passive solar heating for buildings light can be reflected to a focus by a curved mirror low maintenance no need for power cables no need for fuel long life renewable energy resource no polluting waste no power at night at night or in bad weather energy absorbed by photocell electrons are knocked loose from the silicon atoms in the crystal electrons flow freely light intensity surface area exposed distance from the light source renewable no polluting waste visual pollution dependency on wind speed appropriate space and position glass is transparent to suns radiation heated surfaces emit infrared radiation of longer wavelength glass reflects this longer wavelength infrared To be efficient a solar collector must track the position of the Sun in the sky. Why do some solar collectors change position during the day? Describe how to generate electricity. Take a coil of wire and a magnet and move either the wire or the magnet. This is called the dynamo effect. Describe and recognise the ways that the dynamo effect can be increased (to give more current). Describe how simple AC generators work. What type of current does a generator produce? stronger magnetic field more coils move magnet or coil faster coil of wire magnetic field coil and field close relative motion between coil and field alternating current (ac)

2 Draw a voltage-time graph to show alternating current. What type of current does a battery produce? Describe the main stages in the production and distribution of electricity. see your exercise book or revision guide direct current (dc) source of energy power station produces electricity national grid of power lines connecting station to consumers consumers are homes, factories, offices and farms. Describe how electricity is generated at a burning fuel conventional power station producing steam spinning a turbine turbine turns generator Do power stations convert all of the energy available into electrical energy? No lots of energy is wasted, mainly as heat energy. What does efficiency tell us? How much useful energy is produced compared to the input energy. Describe and explain the greenhouse effect. When some gases in the Earth s atmosphere prevent heat from radiating into space. Most wavelengths of radiation can pass through the Earth s atmosphere, but certain wavelengths particularly infrared, are absorbed by some gases in the atmosphere. short wavelength e-m radiation from the Sun is absorbed by and heats the Earth the Earth radiates heat as longer wavelength infrared radiation greenhouse gases absorb some infrared radiation, warming the atmosphere Name three greenhouse gases. carbon dioxide water vapour methane Describe three causes of global warming. increased energy use increased CO2 emissions deforestation Describe the difficulties of measuring Need data over many years global warming and explain why scientists working on global warming should allow other scientists to use their data. Other factors (ie the weather) effect the temperature Explain how dust in the atmosphere can affect the weather. from factories reflecting radiation from the city back to Earth causing warming from volcanic ash and gases reflecting radiation back from the Sun back into space causing cooling. What is a fuel? A substance that releases energy as heat. Name the common fuels used in power fossil fuels stations. renewable biomass wood, straw and manure nuclear fuels uranium and sometimes plutonium What is the unit of power? watt or kilowatt

3 What is the unit of electrical energy kilowatt hour supplied? What factors affect the cost of using an power rating in watts and kilo watts electrical appliance? the length of time it is switched on. What does a transformer do? Increase or decrease voltage Explain why transformers are used in the National Grid to increase the voltage. electrical energy is transmitted at high voltage to reduce energy waste and costs for a given power transmission, an increased voltage reduces current, so decreasing energy waste by reducing heating of cables. disadvantages (for consumers and producers) of using off-peak electricity in the home. Name the three types of nuclear radiation. Describe uses of the three types of radiation. Describe the relative penetrating power of alpha, beta and gamma. Interpret data and describe experiments that show how alpha, beta and gamma can be identified by their relative penetrating powers. Why can nuclear radiation be dangerous? Demand is spread throughout the day and night Cheaper for consumers. alpha beta gamma alpha smoke detectors beta some traces and paper thickness gauges gamma treating cancer, non-destructive testing tracers and sterilising equipment. alpha stopped by a few sheets of paper beta stopped by a few sheets of aluminium gamma mostly stopped by a few cm of lead see your exercise books or revision guide. It causes ionisation, which can damage the cells and cause cancer. What is ionisation? Nuclear radiation can form positive ions when electrons are lost from atoms Nuclear radiation can for negative ions when electrons are gained by atoms. Ionisation can initiate chemical reactions that damage human cells. Describe how to handle radioactive protective clothing materials safely. tongs / keep your distance short exposure time shielded and labelled storage State three facts about waste from radioactive nuclear power stations. harmful not causing global warming plutonium Name a use of plutonium make nuclear bombs Is uranium a renewable or nonrenewable Non-renewable source. Describe some ways of disposing of low level waste in land-fill sites radioactive waste. encased in glass and left underground reprocessed

4 Explain the problems of dealing with radioactive waste. remains radioactive for a long time terrorist risk must be kept out of groundwater acceptable radioactivity level may change over time relatively cheap disadvantages of nuclear power. abundant supply of uranium does not release greenhouse gases potentially dangerous (e.g. Fukushima, Chenobyl) State the order of the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto Why can stars be seen or detected even They are very large and give off their own light. though they are far away? What is a group of stars called? A Galaxy Put the following in order of size; planets, stars, comets, meteors, galaxies. (smallest) meteor, comet, planet, star, galaxy (largest) Why do the planets orbit the sun? Gravity provides the force to attract the planet to the Sun. This force makes the planet travel in a circle and is called the centripetal force. What is a light year? The distance light travels in a year. Compare the differences between manned and unmanned spacecraft. Describe how information from space can be returned to Earth. See your exercise book or revision guide. distant planets require data to be sent back nearby samples can be brought back to Earth for analysis. Describe how a collision between two the planets collide planets can result in an Earth-Moon system their iron cores merge to form the core of the Earth less dense material orbits as the Moon What are asteroids? rocks as being left over from the formation of the Solar System as being in orbit between Mars and Jupiter Describe some of the consequences of a crater collision of Earth with a large asteroid. ejection of hot rocks widespread fires sunlight blocked by dust climate change species extinction State 4 facts about comets made from ice and dust has a tail formed from a trail of debris have highly elliptical orbits come from objects orbiting the Sun far beyond the planets Describe and explain how the speed of a comet changes as it approaches a star. Explain why the asteroid belt is between Mars and Jupiter. What does NEO stand for? Near Earth Object The comet is fastest when it is close to the star and becomes slow when it is furthest away from the start. This is because the gravitational force is strongest when the comet is close to the star. The gravitational attraction of Jupiter disrupts the formation of a planet.

5 What is an NEO and how can they be seen? How can the threat of NEOs be reduced? An asteroid or comet on a possible collision course with Earth. Seen with a telescope (either on the Earth or on a Satellite). Surveys by telescope Monitoring by Satellites Deflection by explosions (when they are distant enough from Earth) Big Bang started with an explosion the Universe is still expanding expanding How do scientists think the Universe began? What do scientists think the Universe is still doing? Describe the evidence for the Big Bang most galaxies are moving away from us Describe the end of the life cycle of a distant galaxies are moving away more quickly large star; microwave radiation is received from all parts of Red supergiant the Universe Supernova light from other galaxies shifting to the red end of Neutron star or a black hole (for the spectrum massive stars) more distant galaxies generally showing greater red shift estimating the age and starting point of the Universe Describe the end of the life cycle of a red giant small star planetary nebula white dwarf Describe the life cycle of a large star red supergiant supernova neutron star or black hole (for massive stars) Describe the life history of a star interstellar gas cloud gravitational collapse producing a proto star thermonuclear fusion long period of normal life (main sequence) end depends on mass of star What is a black hole? The remains of a star that is so dense that light cannot escape it. Large mass, small volume and high density Strong gravitational attraction due to the large mass Describe and recognise the Ptolemaic See your exercise book and revision guide. and Copernican models of the Universe, and describe how they differ from each other and the modern day model.