P2 - Radiation and Life

P2 - Radiation and Life

1. Ionisation

   • Only some types of electromagnetic radiation have enough energy to do it
     • X - rays
     • Gamma rays
     • Ultraviolet rays
       • Ionising ultraviolet rays are what cause sun burn and skin cancer
         • Cells ionise in cells inside the skin
   • When electromagnetic radiation has enough energy to remove an electron from a cell or molecule
     • Changes cell/molecule
   • Can be dangerous
     • When ionisation happens happens inside the body, it can damage or kill the cell
       • When the cell is killed, this is radiation sickness
       • Ionisation can cause cells to continuously mutate
         • Make copies of themselves over and over, without stopping
           • This is cancer
     • The longer cells are exposed to the ionising radiation, the more damage can potentially be caused

2. The electromagnetic spectrum

   • Includes seven types of radiation
     • Radio
       • Have the longest wavelength
       • Least powerful
     • Microwave
       • Uses
         • Mobile phones
         • Microwaves
         • Satellite communication
     • Infra red
     • Visible
       • Makes up the colours of the rainbow
     • X - rays
     • Gamma rays
       • Have the shortest wavelength
       • Most powerful
   • No fixed boundaries between the types of radaiation
     • High energy types of waves can overlap low energy types of waves next to them in the spectrum

3. Analogue and digital signals

   • Analogue
     • Can contain any value in any range
     • Generally worse quality than digital
       • Any noise picked up is harder to get rid of
         • Hard to tell what the original wave would have looked like
           • Every value in a particular range
       • Noise is amplified along with the original wave
   • Digital
     • Contains only two values
       • On or off
       • True or false
       • 0 or 1
       • Results in a series of short pulses
     • Generally better quality than analogue
       • Noise is easier to get rid of
         • It is obvious what the original wave would have looked like
           • Only two values
         • A wave with noise can easily be changed back to its original state by being amplified

4. Electromagnetic radiation and communication

   • Microwaves
     • Satellite communication
       • Waves are transmitted into space and absorbed by the satellite receiver dish
         • 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
       • Satellite TV
     • Health risks
       • Mobile phones
         • 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
   • Radio waves
     • Good for transmitting information over long distances
       • Don't get absorbed by the Earth's atmosphere
     • Uses
       • TV
       • FM radio