P1 Learning Outcome Questions

Transcription

1 P1 Learning Outcome Questions Question 1. Do hot things or warm things cool down more quickly? 2. In which direction does heat energy always move? Answer Hot things cool down more quickly From a warmer object to a cooler object. 3. What is the name of a photograph that shows thermomgram different temperatures as different colours? 4. What colours are the hottest and coldest temperatures on a thermogram? hottest parts: white/yellow/red coldest parts: black/dark blue/purple. 5. What is heat measured in? Joules 6. What does the temperature of a substance tell us about the particles? Temperature tells us the average kinetic energy of the particles 7. What is the difference between temperature and heat? Temperature a measurement of hotness on an arbitrary or chosen scale. 8. Describe three factors that affect the amount of energy needed to raise the temperature of an object. Heat measurement of energy on an absolute scale mass the material from which it is made the temperature change. 9. Describe what you need to measure in an experiment to measure the energy required to change the temperature of a body. 10. What is the difference between a material with a high specific heat capacity and a material with a low specific heat capacity. 11. Describe and explain what happens to the temperature of an object when it is boiling, melting or freezing?. 12. Explain the meaning of: the specific latent heat of a material. 13. Explain how energy is transferred in terms of: conduction convection radiation 14. Describe how energy is transferred by: conduction convection radiation 15. Explain how there will be energy loss in a cavity wall and what further measures could be taken to limit this loss. 16. Describe everyday examples of energy saving methods in the home. 17. Explain why trapped air in a material is a very good insulator 18. Explain how the property that air is a very good insulator is used to keep homes warm: 19. What happens to infra-red radiation when it hits: a) a shiny surface? b) a dull surface? temperature change mass of material specific heat capacity of material A material with a high specific heat capacity will: need more energy to make it get hotter need to lose more energy before it gets colder. store more energy take longer to heat up take longer to cool down Temperature stays constant (even though energy is still being transferred) For melting and boiling, the energy is being used to break bonds. For freezing, energy is being released when the bonds are made. How much energy is needed to melt or evaporate 1kg of the substance Conduction: energy is transferred from particle to particle Convection: Hot air rises and cool air falls Radiation: Infra-red waves are absorbed and emitted by hot objects conduction transfer of KE between particles. Free electrons in metals transfer energy between particles. convection how expansion when a liquid or gas is heated causes a change of density which results in (bulk) fluid flow radiation infrared radiation is an electromagnetic wave and needs no medium. Energy is lost by convection and conduction between the warm air and the walls. Foam or polystyrene stops the air moving and this reduces the heat loss. loft insulation double glazing cavity wall insulation. reflective foil in or on walls draught-proofing. The particles are far apart and so energy cannot be transferred between the particles fibreglass, mineral or rock wool in loft insulation double glazing in windows insulation foam or fibreglass in cavity walls curtains at windows. reflected from a shiny surface absorbed by a dull or rough surface.

2 20. If heat is lost from the home, what is the heat source and what is the heat sink? 21. If a person buys loft insulation for their house, what is meant by the payback time? 22. Name and label the main features of a transverse wave: Heat source the home Heat sink the surroundings The time taken for the person to save the cost of the loft insulation on their energy bills. trough and crest amplitude wavelength. Use your exercise book or revision book to check the diagram 23. What does frequency mean? The number of waves per second 24. Give two facts about how electromagnetic waves travel In straight lines (unless they change what they are travelling through) at the same high speed in space or a vacuum 25. Draw a diagram to show how a wave is Use your exercise book or revision book to check the diagram reflected. 26. When is a wave refracted? A wave will change direction when it passes from one medium to another. 27. Explain why refraction occurs at the boundary Because the speed of the wave changes between mediums. 28. What is diffraction? When waves spread out at an opening or gap 29. Draw diagrams to show waves being diffracted Use your exercise book or text book to check the diagram. at wide and narrow gaps. 30. For maximum diffraction, how wide should the About the same width as the wavelength gap be? 31. How does diffraction affect the use of telescopes The light is diffracted by small gaps. This can make the and microscopes? image blurred. 32. Describe an example of a communications use Radio radio stations for radio, microwave, infrared and visible light Microwave mobile phones Infra-red TV remote controls 33. State the seven types of electromagnetic waves that comprise the spectrum and place them in order of frequency or wavelength. 34. Why are radio aerials longer than mobile phone aerials? 35. Describe how, historically, light was used as a means of communication Visible light morse code Radio waves (longest wavelength, shortest frequency) Microwaves Infra-red Visible Ultra-violet X rays Gamma rays (shortest wavelength, highest frequency) Because the receiver needs to be about the same size as the wavelength of the radiation they are receiving. signals sent in the form of Morse code which is a series of on off signals signals relayed between stations to cover larger distances. 36. Is morse code an analogue or digital signal? Why? 37. Draw a diagram to show light travelling along an optic fibre. Label where total internal reflection occurs. Digital because it can either be on or off. Use your exercise book or text book to check the diagram. 38. Draw diagrams to show refraction and total internal reflection, and explain the importance of the critical angle Use your exercise book or text book to check the diagrams 39. What type of light does a laser produce? produces a narrow beam of light of a single colour (monochromatic). 40. Explain why most lasers produce an intense waves have the same frequency coherent beam of light: waves are in phase with each other waves have low divergence.

3 41. Explain how a laser beam is used in a CD player By reflection from the shiny surface: information is stored on the bottom surface information is stored digitally information in the form of patterns of bumps (known as pits) a CD will contain billions of pits. 42. State 4 uses of lasers surgery and dental treatment cutting materials in industry weapon guidance laser light shows. 43. Explain the advantages and disadvantages of using light, radio and electrical signals for communication. 44. Explain how the properties of surfaces affect the emission and absorption of infrared radiation. surface (temperature) colour (black or white) texture (shiny or dull). 45. How do microwaves heat up food? The microwaves are absorbed by fat or water in the food and this heats it up. 46. Which type of radiation do mobile phones use? microwaves 47. Describe 2 properties of infrared radiation. heats the surface of the food is reflected by shiny surfaces. 48. Describe 4 properties of microwaves. penetrate (about 1cm) into food are reflected by shiny metal surfaces can cause burns when absorbed by body tissue pass through glass and plastics. 49. Describe and explain how signal loss with microwaves happens 50. Describe how the problems of signal loss are reduced. adverse weather and large areas of surface water scatter signals loss of line of sight due to curvature of the Earth no diffraction of microwaves around large objects interference between signals limiting the distance between transmitters high positioning of transmitters. 51. Explain how microwaves and infrared transfer energy to materials. 52. Describe how the energy associated with microwaves and infrared depend on their frequency and relate this to their potential dangers. infrared is absorbed only by particles on the surface of the food increasing their KE KE is transferred to the centre of the food by conduction or convection microwaves are absorbed only by water or fat particles in outer layers of the food increasing their KE. High frequency = higher energy Higher energy = higher potential danger 53. List the key points about the possible dangers of mobile phones. There may or may not be dangers: - to residents near the site of a mobile phone transmitter mast - to users of mobile phones (especially children) Potential dangers may be increased by frequent use. Publishing scientific studies into the effects of mobile phone microwave radiation enables results to be checked. In the presence of conflicting evidence individuals and society must make choices about mobile phone usage and location of masts in terms of balancing risk and benefit. 54. Describe uses of infrared radiation. in remote controls (TV, video and DVD players, automatic doors) short distance data links for computers or mobile phones. 55. Explain how passive infrared sensors and thermal imaging cameras work. infrared sensors detect body heat.

4 56. Explain how different remote controls are programmed to control different devices 57. Describe the differences between analogue and digital signals 58. Draw graphs to show analogue and digital signals 59. Explain why it is easier to remove noise from most digital signals. 60. Describe advantages of using optical fibres to allow more information to be transmitted. the signal from an infrared remote control uses a set of digital signals (or codes) to control different functions of electrical or electronic devices. analogue signals have a continuously variable value digital signals are either on (1) or off (0). Slight variations of signal will not affect whether at signal is either on or off. multiplexing lack of interference in the final signal. 61. Why is digital TV better than analogue TV? less noise or interference (a clearer picture) multiplexing = more channels 62. Describe the transmission of light in optical fibres. optical fibres allow the rapid transmission of data optical fibres allow the transmission of data pulses using light. 63. Describe the advantages of wireless technology. no external/direct connection to a telephone line needed portable and convenient allows access when on the move but an aerial is needed to pick up the signals. 64. Draw diagrams to show how radiation can be reflected and refracted. 65. Explain how reflection and refraction can be an advantage or disadvantage for good signal reception. 66. Explain how the refraction and diffraction of radiation can affect communications. 67. Describe common uses of wireless technology. TV and radio mobile phones laptop computers. 68. Explain the role of the ionosphere and satellites in long-distance communication. 69. Explain why nearby radio stations use different transmission frequencies. 70. Describe advantages and disadvantages of DAB broadcasts. 71. How can shockwaves caused by earthquakes be measured? 72. What are the possible effects of shockwaves caused by earthquakes? 73. Name the two types of seismic wave and describe their properties. Use your exercise book revision guide to check the diagrams Advantages Radio waves are reflected off the ionosphere. Satellite dishes reflect TV signals to focus them. The atmosphere refracts radio waves so they can curve around the horizon. Disadvantages Mobile phone signals reflect off mountains, causing lack of signal. Refraction of radio waves by the layers of the atmosphere can cause signal loss refraction at the interfaces of different layers of Earth s atmosphere diffraction by transmission dishes results in signal loss the refraction and resulting reflection of waves from the ionosphere (similar to TIR for light) being received by and re-transmitted from satellites. To prevent interference between the different signals more stations available less interference with other broadcasts poorer audio quality compared to FM not all areas covered. be detected by seismometers be recorded on a seismograph cause damage to buildings and the Earth s surface cause a tsunami. longitudinal P waves which travel through both solids and liquids and travel faster than S waves transverse S waves which travel through solids but not through liquids and travel slower than P waves.

5 74. Describe how data on seismic waves transmitted through the Earth can be used to provide evidence for its structure. 75. State the effects of ultraviolet radiation suntan sunburn skin cancer cataracts 76. What are the advantages of using higher factor sunscreens? P waves travel through solid and liquid rock (ie all layers of the Earth) S waves cannot travel through liquid rock (ie the outer core). premature skin aging. less damage when higher factors are used high factors allow longer exposure without burning. 77. Explain how darker skins reduce cancer risk. absorb more ultraviolet radiation less ultraviolet radiation reaches underlying body tissues. 78. Explain how to calculate how long a person can spend in the Sun without burning from knowledge of the sun protection factor (SPF) of sunscreens (eg sun block or suncream). 79. Describe and explain how scientists have discovered a hole in the ozone layer and the effects this has had on society. The SPF tells us how many times longer a person can stay in the sun without burning. The discovery of the reduction of ozone levels over Antarctica was unexpected. Scientists used existing scientific ideas to explain their measurements Scientists verified their measurements of ozone reduction, and the took steps to increase confidence in their explanation: - measurements repeated with new equipment - measurements repeated by different scientists - predictions tested based on the explanation people have been informed of the risk of exposure to ultraviolet radiation, including from the use of sun beds, in order to improve public health. The ozone layer protects the Earth from ultraviolet radiation. Environmental pollution from CFCs has depleted the ozone layer - this allows more ultraviolet radiation to reach Earth - the potential danger to human health increases because of this. The discovery of the hole in the ozone layer over Antarctica changed the behaviour of society at an international level.