Electro magnetic spectrum

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  • Electro magnetic spectrum
    • Goes from smallest to biggest in colours: Infared, Red, Orange, Yellow, Green, Blue, Indigo, Violet
      • Red has the longest wavelength but the lowest freq but violet has the shortest wavelength, higher freq.
      • Infared Waves: have a wavelength between 1 millimetre and 1 thousandth of a mm
        • Emitted by warm or hot objects and reflected by shiny surfaces but absorbed by dark surfaces
    • Radio Waves: sent out in all directions  that are on at all masts on big hills
      • Carry speech or music which is then detected and reproduced  by radio sets in nearby areas
    • Microwaves: are electro magnetic waves with a wavelength from a few mm to a meter
      • Used to send information to satalites into space making possible instant communication around the world
        • Can carry speech, music and pictures info and go straight through ionsphere which is a layer of electronically charged particles high in earths atmosphere
    • Visible Light waves:  Stimlates the light sensitive cells on the retina of the human eye and makes human eyes work
      • The wavelength is less than 1 thousandth of a millimetre.
    • Ultraviolet waves: emitted by suns and lamps that are used in sun beds
      • Can cause skin cancer and damage to human eyes
        • Some chemicals are in hair dye and can absorb uv   rays and re-emit them as visible light
    • Gamma Rays: wavelength is about 0.1 nanometers or less.
      • They can pass through soft materials but harder materials absorb them eg bone
        • `They can also be used to treat life threatening illnesses like cancer as they can be used to chemotherapy but can cause genetic mutation
          • They can kill living bacteria and so are use to clean surgical equipment
            • All travel at the speed of: 3 x 10 to the 8

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