P2: Living for the Future Revision List

GCSE Physics P2 (OCR B712): Living For The Future (Energy Resources)

Year 10 revision topics for P2 OCR GCSE Physics

P2: Living for the Future Revision List

October 22, 2017 admin

P2a Collecting energy from the Sun

  • Recall that photocells:
    • 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.

 

  • Recall that DC electricity is current in the same direction all the time.
  • Describe how the Sun’s energy can be harnessed:
    • radiation from the Sun can be absorbed by a surface and transferred into heat energy
    • produces 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.

 

  • Describe some advantages and disadvantages of using photocells to provide electricity:
    • low maintenance
    • no need for power cables
    • no need for fuel
    • long life
    • renewable energy resource
    • no polluting waste
    • no power at night or in bad weather

 

  • Describe how light produces electricity in a photocell (HL):
    • energy absorbed by photocell
    • electrons are knocked loose from the silicon atoms in the crystal
    • electrons flow freely.

 

  • Understand how the current and power produced in a photocell depends on (HL):
    • light intensity
    • surface area exposed
    • distance from the light source

 

  • Describe the advantages and disadvantages of wind turbines:
    • renewable
    • no polluting waste
    • visual pollution
    • dependency on wind speed
    • appropriate space and position needed.

 

  • Explain why passive solar heating works (HL):
    • glass is transparent to Sun’s radiation
    • heated surfaces emit infrared radiation of longer wavelength
    • glass reflects this longer wavelength infrared
  • Recall that an efficient solar collector must track the position of the Sun in the sky. (HL)

P2b Generating electricity

  • Describe how to generate electricity using the dynamo effect, by moving the coil or the magnet.
  • Recall that a generator produces alternating current(AC).
  • Recall that a battery produces direct current (DC).

 

  • Describe the main stages in the production and distribution of electricity:
    • source of energy
    • power station produces electricity
    • national grid of power lines connecting station to consumers
    • consumers are homes, factories, offices and farms

 

  • Recognise that there is significant waste of energy in a conventional power station.
  • Use the equation in the context of a power station:
  • given the useful energy output and the total energy input. Efficiency can be expressed in ratio or percentage terms.
    • coil of wire
    • magnetic field
    • coil and field close
    • relative motion between coil and field

 

  • Describe how simple AC generators work:
  • Describe and recognise the ways that the dynamo effect can be increased (to give more current).
  • Describe and interpret AC using a voltage-time graph.
  • Describe how electricity is generated at a conventional power station:
    • burning fuel
    • producing steam
    • spinning a turbine
    • turbine turns generator

 

  • Use the equation in the context of a power station: given the useful energy output, wasted energy and the total energy input. Efficiency can be expressed in ratio or percentage terms.
  • Use the equation in the context of a power station to calculate useful energy output, total energy input or wasted energy.(HL)Efficiency can be expressed in ratio or percentage terms.

P2c: Global warming

  • Understand that some gases in the Earth’s
  • atmosphere prevent heat from radiating into space.
  • Recall and recognise that this is known as the greenhouse effect.

 

  • Recall and identify examples of greenhouse gases to:
    • carbon dioxide
    • water vapour
    • methane

 

  • Describe reasons for climate change caused by increased global warming:
    • increased energy use
    • increased CO2 emissions
    • deforestation.
  • Describe the difficulties of measuring global warming.
  • Explain why scientists working on global warming should allow other scientists to use their data.
  • Describe how electromagnetic radiation at most wavelengths can pass through the Earth’s atmosphere, but certain wavelengths, particularly infrared, are absorbed by some gases in the atmosphere.

 

  • Explain the greenhouse effect in terms of: (HL)
    • 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.

 

  • Recall and identify natural and man-made sources of greenhouse gases (limited to water vapour, carbon dioxide and methane).
  • Interpret data about the abundance and relative impact of greenhouse gases (limited to water vapour,carbon dioxide and methane) (HL).
  • Explain how human activity and natural phenomena both have effects on weather patterns including dust in the atmosphere:
    • from factories reflecting radiation from the city back to Earth causing warming
    • from volcanic ash and gases reflecting radiation from the Sun back into space causing cooling.

 

  • Interpret data about increased global warming and climate change as a result of natural or human activity (no recall is expected) (HL).
  • Describe scientific evidence which supports or refutes the idea of man-made global warming.
  • Distinguish between opinion and evidence based statements in the context of the global warming debate.
  • Explain how it is possible to have good agreement between scientists about the greenhouse effect, but disagreement about whether human activity is affecting global warming. (HL)

P2d Fuels for power

  • Recall that fuels release energy as heat.
  • Recall the common fuels used in power stations:
    • fossil fuels
    • renewable biomass – wood, straw and manure
    • nuclear fuels – uranium and sometimes plutonium

 

  • Recall that transformers can be used to increase or decrease voltage.
  • Recall that the unit of power is the watt or kilowatt.
  • Interpret data to show that the cost of using expensive electrical appliances depends on:
    • power rating in watts and kilowatts
    • the length of time it is switched on.

 

  • Calculate the power rating of an appliance using the equation:
    • power = voltage × current

 

  • Describe and evaluate the advantages and disadvantages of different energy sources; availability, risks and environmental impact.
  • Calculate the power rating of an appliance using the equation, including conversion of power between watts and kilowatts:
    • power = voltage × current

 

  • State that the unit of electrical energy supplied is the kilowatt hour.
  • Calculate the number of kilowatt hours given the:
    • power in kilowatts
    • time in hours.

 

  • Use the equation:   energy supplied = power × time
  • Calculate the cost of energy supplied.
  • Use the kilowatt hour as a measure of the energy supplied. (HL)
  • Use and manipulate the equation:   power = voltage × current (HL)
  • Use the equation:  energy supplied = power × time   to calculate (HL):
    • power in kW or W
    • time in hours.

 

  • Describe the advantages and disadvantages (for consumers and producers) of using off-peak electricity in the home.
  • 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.

 

  • Explain how, for a given power transmission, an increased voltage reduces current, so decreasing energy waste by reducing heating of cables. (HL)

P2e: Nuclear radiations

  • Recognise examples where nuclear radiation can be beneficial or harmful:
    • state one example of a beneficial use
    • harmful effect: damages living cells/causes cancer.
  • Understand that radioactive materials give out nuclear radiation over time.

 

  • Recall the three types of nuclear radiation:
    • alpha – helium nuclei
    • beta – electrons
    • gamma
  • Understand that nuclear radiation causes ionisation and this is potentially harmful.

 

  • Describe how to handle radioactive materials safely:
    • protective clothing
    • tongs / keep your distance
    • short exposure time
    • shielded and labelled storage.

 

  • Describe waste from nuclear power as:
    • radioactive
    • harmful
    • not causing global warming

 

  • Describe examples of beneficial uses of radiation:
    • alpha – smoke detectors
    • beta – some tracers and paper thickness gauges
    • gamma – treating cancer, non-destructive testing,tracers and sterilising equipment

 

  • Describe the relative penetrating power of alpha, beta and gamma:
    • alpha stopped by a few sheets of paper
    • beta stopped by a few mm of aluminium
    • gamma mostly stopped by a few cm of lead.

 

  • Understand that nuclear radiation can form positive ions when electrons are lost from atoms.
  • Understand that nuclear radiation can form negative ions when electrons are gained by atoms.
  • Interpret data and describe experiments that show how alpha, beta and gamma can be identified by their relative penetrating powers. (HL)
  • Understand that ionisation can initiate chemical reactions. (HL)
  • Explain how ionisation can damage human cells. (HL)
  • Recall that uranium is a non-renewable resource.
  • Recall that plutonium:
    • is a waste product from nuclear reactors
    • can be used to make nuclear bombs

 

  • Describe some ways of disposing of radioactive waste eg:
    • low level waste in land-fill sites
    • encased in glass and left underground
    • reprocessed

 

  • Describe the advantages and disadvantages of nuclear power. (HL)
  • Explain the problems of dealing with radioactive waste (HL):
    • remains radioactive for a long time
    • terrorist risk
    • must be kept out of groundwater
    • acceptable radioactivity level may change over time

 

P2f: Exploring our Solar System

  • Identify the relative positions of the Earth, Sun and planets (includes the order of the planets).
  • Recall that the Universe consists of:
    • stars and planets
    • comets and meteors
    • black holes
    • large groups of stars called galaxies.

 

  • Explain why stars give off their own light and can be seen or detected even though they are far away.
  • Recall that radio signals take a long time to travel through the Solar System.
  • Compare the resources needed by manned and unmanned spacecraft.
  • Describe why unmanned spacecraft are sent into space.

 

  • Recall the relative sizes and nature of planets, stars, comets, meteors, galaxies and black holes.
  • Recall that circular motion requires a centripetal force. (HL)
  • Understand that gravitational attraction provides the centripetal force for orbital motion.
  • Describe a light-year as the distance light travels in a year.
  • Describe some of the difficulties of manned space travel between planets.

 

  • Explain why a light-year is a useful unit for measuring very large distances in space. (HL)
  • Recall that unmanned spacecraft can withstand conditions that are lethal to humans.
  • Compare how information from space is returned to Earth from different distances:
    • distant planets require data to be sent back
    • nearby samples can be brought back to Earth for analysis.

 

  • Explain the advantages and disadvantages of using unmanned spacecraft to explore the Solar System. (HL)

P2g: Threats to Earth

  • Recall that asteroids are rocks.
  • Recall that large asteroids have collided with the Earth in the past.
  • Understand that the Moon may be the remains of a planet which collided with the Earth billions of years ago.

 

  • Describe some of the consequences of a collision with a large asteroid:
    • crater
    • ejection of hot rocks
    • widespread fires
    • sunlight blocked by dust
    • climate change
    • species extinction
  • Describe the make up of a comet:
    • made from ice and dust
    • has a tail formed from a trail of debris.

 

  • Describe a Near Earth Object (NEO) as an asteroid or comet on a possible collision course with Earth.
  • Describe how NEOs may be seen.
  • Describe how a collision between two planets can result in an Earth-Moon system:
    • the planets collide
    • their iron cores merge to form the core of the Earth
    • less dense material orbits as the Moon

 

  • Discuss the evidence for the Earth-Moon system as the result of a collision between two planets. (HL)
  • Describe asteroids:
    • as being left over from the formation of the Solar System
    • as being in orbit between Mars and Jupiter.

 

  • Describe some of the evidence for past asteroid collisions:
    • layers of unusual elements in rocks
    • sudden changes in fossil numbers between adjacent layers of rock

 

  • Explain why the asteroid belt is between Mars and Jupiter (HL):
    • the gravitational attraction of Jupiter disrupts the formation of a planet.

 

  • Describe comets:
    • as having highly elliptical orbits
    • as coming from objects orbiting the Sun far beyond the planets.

 

  • Describe how the speed of a comet changes as it approaches a star.
  • Explain in terms of changing gravitational attraction, why the speed of a comet changes as it approaches a star (HL)
  • Describe how observations of NEOs can be used to determine their trajectories.
  • Explain why it is difficult to observe NEOs.

 

  • Suggest and discuss possible actions which could be taken to reduce the threat of NEOs (HL):
    • surveys by telescope
    • monitoring by satellites
    • detection by explosions (when they are distant enough from Earth)

P2h Big Bang

  • Describe some ideas about the Big Bang theory for the origin of the Universe:
    • started with an explosion
    • the Universe is still expanding.
  • Recall that stars:
    • have a finite life’
    • start as a huge gas cloud
    • are different sizes.

 

  • Understand why not even light can escape from black holes.
  • Recognise that the accepted models of the size and shape of the Universe have changed over time.
  • Describe and recognise the Ptolemaic and Copernican models of the Universe, and describe how they differ from each other and the modern day model.
  • Recall that:
    • most galaxies are moving away from us
    • distant galaxies are moving away more quickly
    • microwave radiation is received from all parts of the Universe

 

  • Explain how the Big Bang theory accounts for (HL):
    • light from other galaxies shifting to the red end of the spectrum
    • 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 small star:
    • red giant
    • planetary nebula
    • white dwarf.

 

  • Describe the end of 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: (HL)
    • interstellar gas cloud
    • gravitational collapse producing a proto star
    • thermonuclear fusion
    • long period of normal life (main sequence)
    • end depends on mass of star.

 

  • Explain the properties of a black hole (HL):
    • large mass, small volume and high density
    • strong gravitational attraction due to the large mass.

 

  • Describe the evidence or observations that caused Copernicus and Galileo to develop new scientific models of the Universe, and explain how technological advances contributed to the new models.
  • Explain why the theories of the Copernicus and Galileo models were considered controversial when they were announced, and were not widely adopted until many years had passed. (HL)