P2 - Radiation and Life

Ionisation
1. Only some types of electromagnetic radiation have enough energy to do it
  1. X - rays
  2. Gamma rays
  3. Ultraviolet rays
    1. Ionising ultraviolet rays are what cause sun burn and skin cancer
      1. Cells ionise in cells inside the skin
2. When electromagnetic radiation has enough energy to remove an electron from a cell or molecule
  1. Changes cell/molecule
3. Can be dangerous
  1. When ionisation happens happens inside the body, it can damage or kill the cell
    1. When the cell is killed, this is radiation sickness
    2. Ionisation can cause cells to continuously mutate
      1. Make copies of themselves over and over, without stopping
        This is cancer
  2. The longer cells are exposed to the ionising radiation, the more damage can potentially be caused
The electromagnetic spectrum
1. Includes seven types of radiation
  1. Radio
    1. Have the longest wavelength
    2. Least powerful
  2. Microwave
    1. Uses
      1. Mobile phones
      2. Microwaves
      3. Satellite communication
  3. Infra red
  4. Visible
    1. Makes up the colours of the rainbow
  5. X - rays
  6. Gamma rays
    1. Have the shortest wavelength
    2. Most powerful
2. No fixed boundaries between the types of radaiation
  1. High energy types of waves can overlap low energy types of waves next to them in the spectrum
Analogue and digital signals
1. Analogue
  1. Can contain any value in any range
  2. Generally worse quality than digital
    1. Any noise picked up is harder to get rid of
      1. Hard to tell what the original wave would have looked like
        Every value in a particular range
    2. Noise is amplified along with the original wave
2. Digital
  1. Contains only two values
    1. On or off
    2. True or false
    3. 0 or 1
    4. Results in a series of short pulses
  2. Generally better quality than analogue
    1. Noise is easier to get rid of
      1. It is obvious what the original wave would have looked like
        Only two values
      2. A wave with noise can easily be changed back to its original state by being amplified
Electromagnetic radiation and communication
1. Microwaves
  1. Satellite communication
    1. Waves are transmitted into space and absorbed by the satellite receiver dish
      1. Then transmitted back to Earth in a different direction
        Received by a satellite dish on the ground
        Made of metal
        Reflects microwaves rather than absorbs them
    2. Satellite TV
  2. Health risks
    1. Mobile phones
      1. When you make a call on your mobile, it emits microwave radiation
        Radiation could heat tissues such as the brain and jaw
        Could increase risk of medical conditions
        Cancers
        No conclusive evidence
        Won't find out until effects start to show
2. Radio waves
  1. Good for transmitting information over long distances
    1. Don't get absorbed by the Earth's atmosphere
  2. Uses
    1. TV
    2. FM radio

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P2 - Radiation and Life

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