Presentation on theme: "Ideas about the solar system have changed over time"— Presentation transcript:
1 Ideas about the solar system have changed over time P1.1 The Solar SystemIdeas about the solar system have changed over timeGeocentric model = Ptolemy = explained the Sun, moon and the planets move in orbits and that Earth was at the centre.Heliocentric model = Copernicus= sun was at the centre and everything went round the Sun.Church = did not like Copernicus idea.Galileo = used telescope to prove Copernicus was right.Galileo observed Jupiter’s moons. By plotting their positions he provided more evidence for the heliocentric model.
2 We can detect these waves. P1.1 The Solar SystemHow do we know about the Solar System and the Milky Way?Telescope = observe space - advantage see more than just with the naked eye.Luminous Objects = give out light that travels as a wave.Non luminous objects = give out waves such as Radio waves and microwaves.We can detect these waves.As telescopes improved, more planets were discoveredComparing different ways of looking at space…Telescopes provide greater magnification than the naked eye.Telescopes provide continuous images.Photographs provide a picture from one moment in time.Photographs can be studied at a later date.You need a way to capture telescope images to preserve them.
3 P1.2 Refracting telescopes Key words:Lens - a transparent block that causes light to refract Refraction – changes the direction the light travels in. It occurs when light passes from one substance to another e.g. air and glass.Converging lens (or convex lens) - is curved on both sides. This means the light rays coming out of it come together at a point – they converge.Focal point – the point at which light rays from a very distant object meet.Measuring the focal lengthThe focal length is found by focussing a distant object on a piece of paper through the lens. The focal length is the distance between the centre of the lens and the image.A converging lens is used in a refracting telescope to focus the image. Galileo’s telescope would have been a refracting telescope.Waves are always refracted at boundaries between different materials
4 P1.2 Refracting telescopes A refracting telescope works bending light through a lens so that it forms an image.Large lenses are needed to collect a lot of light .The objective lens focuses the light to the focal point of the lens.This point is also the focal point of the more powerful eyepiece lens.The eyepiece lens produces a magnified image of the image from the objective lens which the viewer can see.You don’t need to draw this diagram but you do need to explain how the eyepiece lens enlarges the image
5 P1.2 Refracting telescopes RefractionLight waves change speed when they pass across the boundary between two substances with different densities, such as air and glass.This causes them to change direction and this effect is called refraction.There is one special case you need to know. There is no change in direction if they cross the boundary at an angle of 90° - in that case they carry straight on.normalincident rayrefracted rayRefracting telescopes need to be long in order to have large magnification.
6 P1.3 Lenses Converging lenses Their magnification is affected by How curved they areA real image can be projected onto a screen.A virtual image cannot be projected onto a screen. The image formed by a plane mirror is virtual
7 P1.4 Reflecting telescope Refracting telescope.P1.4 Reflecting telescopeIn order to collect as much light as possible, the objective lens needs a large diameter.Large lenses are very difficult to make and so are very expensive.Reflecting telescopes overcome this by using relatively cheap mirrors as their objective.These can be made extremely large.How they work…Reflecting telescopes have a curved mirror instead of an objective lens.The primary mirror focuses parallel light rays from a distant object.The eyepiece lens magnifies this image
8 P1.5 Waves Key definition: Waves transfer energy and information without transferring matter.Key words:Wavelength – The distance from one peak (or trough) to the next.Frequency – The number of waves passing a point per second.Amplitude – the maximum distance of particles in a wave from the normal.2 equations you need to be able to use:Wave speed = frequency x wavelengthWave speed = distance/time
9 P1.5 WavesLongitudinal waves The vibrations are parallel to the direction of travel of the wave e.g. sound waves. Transverse waves The vibrations are at 90 0 to the direction of travel of the wave e.g. electromagnetic waves. Seismic waves can be longitudinal (when the crust moves back and forth, or transverse when the crust moves up and down.
10 Know these two scientists and their work! P1.6 Beyond the visibleKnow these two scientists and their work!Herschel put dark coloured filters on telescope to observe the Sun.He noticed that the filters heated up the telescope to different extents.He used a prism to test this and put thermometers in each colour of light.As he moved from violet to red, the temperature increased.Just beyond the red was even hotter.He discovered infra red waves.Ritter investigated the violet end of the spectrum.He put silver chloride at each end of the spectrum. It turned black more quickly at the violet end than the red end.It turned black even more quickly just beyond the violet.This was called ultraviolet waves.All electromagnetic waves are transverse.They transmit energy at right angles to the direction of the vibration.
11 P1.7 The Electromagnetic Spectrum Learn these in orderAll electromagnetic waves are transverse.All electromagnetic waves travel at the same speed in a vacuum.The electromagnetic spectrum in continuous from radio waves to gamma raysThe different radiations are grouped in order of decreasing wavelength and increasing frequency
12 P1.8 electromagnetic dangers The higher the frequency the more energy that they carry.High-frequency electromagnetic waves, such as gamma rays, are potentially more harmful because they have more energy.All waves transfer energy.Bodies are made of mostly water - waves can heat water.At the moment there is no evidence to support mobile phones could be harmful to the bodyWaveEffect on the bodyMicrowavesInternal heating of body cellsInfra redBurns skinUltravioletDamage to surface cells and eyes leading to skin cancer and eye conditionsX-rays and gamma raysCauses mutations and damage to cells in the bodyIR radiation used in grills and toasters.Our skin absorbs IR = makes us warm.Too much can cause burns to the skin.
13 P1.9 using electromagnetic radiation UseRadio wavesBroadcasting, communication and satellite transmissionsMicrowavesCooking, communications and satellite transmissionsInfra redCooking, thermal imaging short range communication, optical fibres, television remote controls, security systemsVisibleVision, photography, illuminationUltravioletSecurity marking, fluorescent lamps, detecting forged bank notes, disinfecting waterX-raysObserving internal structure of objects, airport security scanners, medical x-raysGamma raysSterilising food and medical equipment, detection of cancer, treatment of cancer
14 P1.10 Ionising radiationIonising radiation is emitted all the time by radioactive sources.Ionising radiation includes alpha and beta particles and gamma rays.These three types of ionising radiation transmit energy and can all damage cells.It is called ionising as it removes electrons from atoms to form ions.Ions are very reactive and if there are a lot of them in cells, they can damage DNA.
16 P1.11 The Universe Facts: The moon is 30 ‘earths’ away The sun is 11,000 ‘earths’ awayP1.11 The UniverseKeywordsStar – a large ball of gas that produces heat and light energy from fusion reactionsMilky Way– The name of our galaxyNebula – a cloud of gas in space. Some objects that look like nebulae are actually cluster of stars or other galaxiesSolar system– an area of space in which object are influenced by the Sun’s gravityGalaxy– a group of millions of stars held together by gravityUniverse– all the stars, galaxies and space itselfAncient astronomers observations / ideas:Stars further away than planetsStars in a shell around earth at the same distanceSaw patches of ‘fuzz’ light (nebulae)Band of light across the sky = Milky WayGalileoUsed basic telescopes but could only see 6 planetsModern observations:8 planets plus dwarf plants, many moons and asteroidsSun is one of millions of stars in the galaxy (Milky Way)Billions of other galaxiesAll these galaxies make up the universe
17 P1.12, 1.13 – Spectrometers and Exploring the Universe KeywordsSpectrum – The range of colours between red and violet obtained when white light is split using a prism.Spectrometer – An instrument that can split up light to show the colours of the spectrumVisible light – Electromagnetic waves that can be detected by the human eyeElectromagnetic spectrum – The entire frequency range of electromagnetic wavesX-ray – electromagnetic radiation that has a shorter wavelength than UV but longer than gamma raysUltraviolet– electromagnetic radiation that has a shorter wavelength that visible light but longer than X raysFactsLight from the sun is a mixture of different colours.Each colour light has a different wavelength and frequency.They can be split with a prism or something with lots of lines like a CD or DVD.A device that can split different wavelengths is called a spectrometerThe atmosphere absorbs some wavelengths so they never reach earth.TelescopesEarly telescopes detected only visible lightModern telescopes detect all parts of the Electromagnectic spectrum (see diagram above)Hubble Space telescope – in orbit around earth since 1990Clear images as it is above the atmosphere so does not get interference from clouds and dust
18 Investigating the Solar System Beyond the Solar System P1.14 –Alien Life?Keywords – (all from previous slide B1.12 and 1.13 also needed)Landers – a space vehicle that lands on a planet or a moonSpace probes – a space vehicle that can be put into orbit around a planet or moon, or parachuted down through the atmosphere.Rovers– a space vehicle that can move about on a planet or moon.SETI - Search for Extraterrestrial Intelligence)Investigating the Solar SystemEarth is the only place where we know life exists.Viking landers have been to marsAnalysed soil for evidence of lifeNo evidence discoveredWater is needed for lifeSpace probes orbiting Mars have detecting channel caused by water flowingRovers used to take close up photographsBeyond the Solar SystemPlanets discovered orbiting other starsThey are too far away to get clear imagesOxygen in the atmosphere would be proof of life.SETIA project that analyses radio waves coming from space.Looks for signals that could be from intelligent being.No messages detected yet.
19 P1.15 Life cycles of stars Keywords Protostar – A cloud of gas drawn together by gravity that has not yet started to produce its own energy.Fusion reaction– when the nuclei of two atoms join together and release energyRed giant– A start that has used up all the hydrogen in its core and is now using helium as a fuel. It is bigger than a normal star.White dwarf– A very dense star that is not very bright. A red giant turns into a white dwarf.Supernova – An explosion produced with the core of a red supergiant collapses.Red Supergiant– A star that has used up all the hydrogen in its core and has a mass much higher than the Sun.Black hole– Core of a red supergiant that has collapsed. Only created when the remaining core has a mass 3-4 times that of the sun.Neutron Star– Core of a red supergiant that has collapsed.
20 P1.15 Life cycles of stars (cont’d) NebulaSuns remain stable for billions of years.As the nebula heat up it glowsMore mass attracted which increases gravity and compresses material into a protostar.ProtostarTemperatures and pressure increase.Hydrogen nuclei fuse to make helium.Fusion reactions release energy as EM radiation.MAIN SEQUENCE of the life cycleRed GiantOnce most Hydrogen fused the star is not hot enough to withstand gravity and collapsesForms a Red giantWhite DwarfStar is Red giant for billions of yearsGas shell thrown off so it collapses into a white dwarf.Cools slowly to become a black dwarf.P1.15 Life cycles of stars (cont’d)Massive starsHotter and brighterFusion reactions are fasterBecome red supergiantsRapidly collapses and explode (supernova)SupernovaOuter layers cast off and expand outwardsTwo optionsIf 3-4 times heavier than the sun = Black hole (gravity so strong not even light can escape)Anything smaller forms a neutron star.
21 P1.16 Theories about the Universe Light moving away from us is detected with a longer wavelength than expected. It is shifted towards the Red end of the spectrum = RED SHIFTLight from other galaxies does this showing they are moving away from us.UNIVERSE IS EXPANDINGSTEADY STATE THEORYUniverse always existed and is expandingNew matter continuously created so it always looks the sameRed shift supports this theory as well as the Big Bang theory.No longer accepted theoryBIG BANG THEORYStart - Tiny point of concentrated energy billions of years agoAll matter existed at this pointExpanding from this pointGravity caused matter to clump forming starsCosmic Microwave Background (CMB) radiation (microwave signals from all over the sky) provided proof for the Big Bang TheoryAccepted theory today
22 P1.17 – Red shiftKeywordsRed Shift– waves emitted by something moving away from an observer have their wavelength increased and frequency decreased compared to waves from a stationary object.Doppler Effect – the change in pitch of a sound coming from a moving sourcePitch – whether a sound is high or lowSound waves behind a moving source become stretched making the frequency lower and the wavelength longer. Similar effect occurs in RED SHIFTVISIBLE SPECTRUM contains gaps. If they are red shifted the star is moving away from usFurther away galaxies are moving the fastest
24 Studying animal movements P1.18 – InfrasoundKeywordsFrequency – number of complete waves that pass a point in one secondHertz – unit of measurement for frequencyLongitudinal waves– the direction of energy is parallel to the direction of vibration which causes themInfrasound – sound with frequency below 20Hz (cannot be heard)Uses of infrasoundStudying animal movementsElephants, whales and giraffes communicate using infrasoundAnimals can be tracked in difficult areas (forests)Monitoring volcanoesInfrasound travels a long wayUsed to monitor volcanoes in remote locations from a distanceDetecting meteorsSome enter atmosphere unseenHelps us determine how many enter and the risks of impact
25 P1.19 – Ultrasound Keywords Ultrasound – sound waves with a frequency above 20,000Hz, which is too high for the human ear to detect.Sonar – a way of determining distance to an object by timing how long it takes for a pulse of ultrasound to be reflected.Reflected – when a wave bounces off a boundary between two materialsUltrasoundHumans detect sound waves between 20 – 20,000HzAbove 20,000Hz = UltrasoundSome animals use it to communicate (dolphins)SonarUsed by some animals (bats) to detect obstaclesUltrasound waves made by animals reflect as echoesUsed by humans in ships to detect fish, sea depthEquationDistance (m) = speed(m/s) x time (s)Ultrasound ScanMake images of things inside the bodyExample of use – to scan an unborn baby to check developmentdifferent parts of the baby reflect the sound in different ways to create the image on the screen.
26 P1.20 – Seismic wavesSeismic waves – Waves produced by an explosion or earthquake and which travel through the earth.Focus (of earthquake) – the place where an earthquake begins (usually under the surface)Epicentre – The point on the surface of the Earth directly above the focus of an earthquakeP waves – Longitudinal seismic waves that travel through the earthS waves – Transverse seismic waves that travel through the earthMovements inside the earth cause seismic waves to be transmittedWhen waves reach the surface = ground shakesSeismometers detect these wavesPlace where the original movement or fracture occurs = focus and the epicentre is the surface directly above the focus.Investigating the EarthScientists investigate waves but setting controlled explosions or dropping masses from a truckThe waves reflect and refract giving information about the rocks belowUsed to look fro oil or locate changes in rock type.
27 P1.21 and 1.22 – Earthquakes and Detecting Earthquakes Keywords Tsunami – a huge wave caused by an earthquake or landslide on the sea bed Tectonic Plates – Pieces of the surface of the Earth, which can move around very slowly Convection currents – a current caused by parts of a fluid being at a different temperature and so a different density to the rest of the fluid.Detecting earthquakesNetwork of seismometers around the worldCalculate the arrival times of different waves (P and S) to work out epicentre of earthquakePredicting earthquakes and tsunamisUse plate boundaries to predict likely locationsCannot measure the forces moving plates or the friction which makes predicting earthquakes difficult.An earthquake under the sea causes a huge wave (Tsunami)Tsunami warning systems include pressure sensors to detect wavesSeisometer traces do not give warningTsunamis travel at different speeds so this can give an opportunity for warnings to be given.EarthquakesOuter layer of earth = tectonic platesThey are pushed slowly by convection currents in the mantleFriction between them stops the movement until the force gets big enough and a jerk happens = earthquake
28 1.23 Renewable resources for electricity Key words:Current – the flow of charge.Voltage – electrical pressure giving a measure of the energy transferred.Renewable energy source – will not run out.
29 Type of energyAdvantagesDisadvantagesSolarPotentially infinite energy supply.Single dwellings can have own electricity supply.No harmful gases produced.Manufacture and implementation of solar panels can be costly.WindCan be found singularly, but usually many together in wind farms.Manufacture and implementation of wind farms can be costly.Some local people object to on-shore wind farms, arguing that it spoils the countryside.TidalIdeal for an island such as the UK.Potential to generate a lot of energy.Tidal barrage can double as a bridge, and help prevent flooding.Construction of barrage is very costly.Only a few estuaries are suitable.Opposed by some environmental groups as having a negative impact on wildlife.May reduce tidal flow and impede flow of sewage out to sea.WaveIdeal for an island country.More likely to be small local operations, rather than done on a national scale.Construction can be costly.May be opposed by local or environmental groups.GeothermalUsed successfully in some countries, such as New Zealand and Iceland.Can be expensive to set up and only works in areas of volcanic activity.Geothermal and volcanic activity might calm down, leaving power stations redundant.Dangerous elements found underground must be disposed of carefully.Hydrological or Hydroelectric Power (HEP)Creates water reserves as well as energy supplies.Costly to build.Can cause the flooding of surrounding communities and landscapes.Dams have major ecological impacts on local hydrology.
30 P1.24 Non-renewable resources Type of fuelAdvantagesDisadvantagesCoal (fossil fuel)Ready-made fuel.It is relatively cheap to mine and to convert into energy.Coal supplies will last longer than oil or gas.When burned coal gives off atmospheric pollutants, including greenhouse gases.Oil (fossil fuel)Oil is a ready-made fuel.Relatively cheap to extract and to convert into energy.When burned, it gives off atmospheric pollutants, including greenhouse gases.Only a limited supply.Natural gas (fossil fuel)Gas is a ready-made fuel.It is a relatively cheap form of energy.It's a slightly cleaner fuel than coal and oil.Only limited supply of gas.NuclearA small amount of radioactive material produces a lot of energy.Raw materials are relatively cheap and can last quite a long time.It doesn't give off atmospheric pollutants.Nuclear reactors are expensive to run.Nuclear waste is highly toxic, and needs to be safely stored for hundreds or thousands of years (storage is extremely expensive).Leakage of nuclear materials can have a devastating impact on people and the environment. The worst nuclear reactor accident was atChernobyl, Ukraine in 1986.
31 P1.26 Generating Electricity Factors that affect the size of an induced current:Using a coil of wire or increasing the number of turns on the coil.Use an iron core.Use a stronger magnet.Move the wire faster.Factors that affect the direction of an induced current:The direction of the movement of the wire.The direction of the movement og the magnet.
32 P1.26 Generating Electricity Key words:Direct Current (D.C.) – A current that flows in one direction.Alternating Current (A.C) – A current whose direction changes many times a second.Electromagnetic Induction – The process of making a current in a wire as it is passed through a magnetic field.For a continuous current, the wire or the magnet must be continually moving.In a power station, a large current needs to be induced.Electromagnets are used as they are more powerful than permanent magnets.
33 P1.26 Generating Electricity A GeneratorCurrent is induced in the coil. And transferred to a circuit through the slip rings which touch carbon brushes.As the coil turns the direction of the induced current changes.Alternating Current (A.C.) is induced
34 P1.26 Generating Electricity A DynamoUsed to produce electricity to power cycle lights.Magnet spins inside a coil of wireA current is induced.Direct current (D.C)Other examples are wind up torches or radios.
35 P1.27 Transmitting Electricity Key words:Transformers – change the size of an alternating voltage.Step up transformer – increases the voltageStep down transformer – decreases the voltageElectricity is transmitted at high voltages as it increases efficiency by reducing heat loss in the power lines.
36 P1.27 Transmitting Electricity A transformer consists of two coils wrapped around an iron core.Electricity is supplied to the primary coil and obtained in the secondary coil at a different voltage.You need to be able to use this formula to work out the turns of the voltage:Try these examples…
37 P1.27 Transmitting Electricity Voltage increased to 400,000V to reduce heat lossVoltage reduced to 33,000V for factoriesVoltage reduced to 230/240V for homesHazards of electrical transmissionHigh voltages are likely to kill.
38 P1.28 Paying for Electricity 3 formulae you need to know…Formula 1Key words:Power – the energy transferred per second. Measured in watts (W)Energy from the mains supply is measured in Kilowatt-hours (Kwh)What is the power if the voltage is 12V and the current is 5A?power = 5 × 12= 60W
39 P1.28 Paying for Electricity Formula 2Formula 3Electricity meters measure the number of units of electricity used in a home or other building. The more units used, the greater the cost. The cost of the electricity used is calculated using this equation:cost = power (kW) × time (hour) × cost of 1 kWh (pence)How much energy is used by a 2000W appliance running for 60 seconds?power = 2000 × 60= 120000An electric fire needs 2 kW. It is switched on for 3 hours. If each kWh costs 10p, how much does it cost to run the fire?cost = power × time × cost of 1 kWh = 2 kW × 3 h × 10p = 60p
40 P1.30 Reducing energy use Disadvantages of low energy appliances: initial costuse of extra resources to manufacture new devicecost of disposal of old device.Advantages of low energy appliances:cost efficiencysaving energy and resources.
41 P.31 Energy TransfersEnergy cannot be created or destroyed. It can only be transferred from one type to another.8 types of energy:HeatLightSoundElectricalChemicalNuclear potentialPotential (Gravitational or elastic)KineticEnergy input = Energy output
42 P1.31 Energy TransfersEnergy transfer diagrams show how energy is transferred.The width of the arrows represents the amount of energy transferred at each stage.Example – an old style light bulb.100J of energy are supplied to the bulb. 10J are usefully transferred as light. 90J are transferred as heat.
43 P1.32 EfficiencyKey word:Efficiency – the proportion of energy transferred into useful forms.Example – a new style light bulb.100J of energy are supplied to the bulb. 75J are usefully transferred as light. 25J are transferred as heat.= (75 / 100 ) x 100%= 75%
44 P1.33 Heat RadiationBlack cars heat up more than other cars because they absorb more radiation from the sun.Black is the best colour for radiating heat and absorbing heat.
45 P1.34 The Earth’s temperature For a system to be at a constant temperature, it needs to absorb the same amount of power as it radiates out.