physics 5

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Created by: molly
Created on: 02-04-18 14:21

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Physics topic 5
- Colour
  - Specular refelction
    - this occurs when waves are reflected from a smooth surface
    - if parallel rays of light hit the surface the reflected light rays will also be parallel
  - Diffuse refelction
    - Diffuse reflection occurs when the surface is not smooth
    - The rays are then reflected in many different directions
  - colour spectrum
    - light from the sun or a lamps is white light-a mixture of different colours
      - White light can be slit up into the colours of the visible spectrum by a prism
      - When white light hits a coloured surface some colours are absorbed and some are reflected. The colours that are abosred you can not see and the colours that are reflected are the ones you can see.
  - Fitlers transmit colour
    - so white light hits a filter and the colour of the filter makes coloured light my absorbing some colours and transmitting some
- electromagnetic waves
  - Our eyes can detect certain frequencies-this is called visible light
  - All electromagnetic waves are transervese
    - They travel the same speed in a vacuum (300000000)
- The electromagnetic spectrum
  - see flash cards
- Using long wavelenghs
  - Visible light
    - only part our eyes can detect. Light bulbs emit it and cameras detect it.
  - Infared
    - used for communication, TV to remote, optical fibres sending informaton
    - A grill or toaster transfer energy to food by using infared
    - security systems have sensors that detect infrared, or beams..
  - Microwaves
    - communications and satellite transmissions, mobile phones
    - microwave oven sends microwaves to food to heat it up
  - Radiowaves
    - Transmitting radio broadcast and tv programmes