P2: Radiation and Life

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  • P2: Radiation and Life
    • Uses of electromagnetic radiation
      • Microwaves
        • cooking food
          • Microwave ovens protect people by having metal doors and cases that absorb or reflect the radiation, stopping it from leaking out
        • mobile phone signals
      • Radiowaves
        • transmitting radio and TV signals
      • Infrared
        • to measure temperature in medicine
        • As 'night vision' goggles
          • The hotter the temperature of something the more infrared radiation it emits
            • to measure temperature in medicine
        • optical fibre communication
      • ultraviolet
        • to detect fake bank notes
        • tanning beds
      • visible light
        • Allows humans to see
        • create energy in solar panels
        • helps plants to photosynthesize
      • X-rays
        • To produce pictures of bones in medicine
          • X-rays are weakly absorbed by skin and muscle but strongly absorbed by dense material such as bone and metal
        • To find cracks in metal
          • X-rays are weakly absorbed by skin and muscle but strongly absorbed by dense material such as bone and metal
      • Gamma rays
        • to kill harmful bacteria in food
        • to sterilise surgical instruments
        • used in low doses in cancer traetments
    • dangers of electromagnetic radiation
      • X-rays
        • are ionising so it can change a cell causing damage in in some cases cancer
          • cell damage and death
          • in ionisation, and electron is removed from the atom
      • Gamma rays
        • are ionising so it can change a cell causing damage in in some cases cancer
          • cell damage and death
          • in ionisation, and electron is removed from the atom
      • ultra violet
        • suppression of immune system
        • cataracts
        • sunburn
      • microwaves
        • there is no evidence that exposure to microwaves will harm you however they have a heating effect and so may cause burns in extreme cases
      • radiowaves
        • may lead to Alzheimer's disease
      • infrared
        • can cause cataracts
      • visible light
        • too much light can damage your retina
      • ALARA
        • ALARA stands for As Low As Reasonably Achievable
        • It is a way of making the risk of being exposed to radiation (e.g. when having an X-ray) as small as possible
    • signals
      • analouge
        • can have any range of values
        • vinyl records, tapes
        • includes the whole range of notes in a song- some say this makes it sound better
      • digital
        • can only have two values 0 and 1 (on or off)
        • other sound can disrupt it but it is easier to remove this sound as there are a set amount of values the original wave could be
        • CDs, MP3 files
    • The electromagnetic spectrum from low to high energy:
      • radiowaves, microwaves, infrared, visible light ultra violet, x rays gamma rays
    • Photons
      • Radiation travels in 'packets' called photons
      • the energy of each photon depends on the type of radiation
        • radiowave photons have to lowest energy
        • gamma ray photons have the highest energy
    • Intensity
      • Intensity= the energy arriving at a surface each second
      • the intensity of radiation will decrease the further you are from the source of the radiation
        • some radiation is absorbed
        • the radiation spreads out as it travels

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