THE ELECTROMAGNETIC SPECTRUM

THE ELECTROMAGNETIC SPECTRUM

1. Electromagnetic waves are electric and magnetic disturbances that transfer energy from one place to another.

   • They DO NOT transfer matter.
   • The amount of energy they transfer depends on the wavelength of the waves
     • The energy of the waves increases as the frequency increases

2. The speed of electromagnetic waves.

   • All electromagnetic waves travel at 300 million m/s through space (or in a vacuum).
   • v = f × λ
     • Links the speed of waves to their frequency and wavelength.

3. Light and Colour

   • White light is a mixture of all the colours from the visible spectrum
   • The wavelength increases across the spectrum as you go from violet to red.
   • Colours in spectrum seen when you look at a rainbow, or if you use a glass prism to split a beam of white light
   • Photographers need to know how the shades of colours and light affect the photograph they take
     • 1. On a film camera, the light is focused by the camera lens on to a light sensitive film. The film needs to be developed to see the image photographed.
     • 2. On a digital camera, the light is focused by the lens on to a sensor, which is made of light-sensitve cells called pixels. Each pixel gives a dot of the image. The image can be seen on the camera and is stored on a memory card,

4. Infrared radiation

   • All objects emit infrared radiation
   • The hotter an object is, the more infrared radiation it emits.
   • Infrared radiation is absorbed by the skin
     • Too much exposure heats cells up and can damage or kill them.

5. Microwaves

   • Between radio waves and infrared radiation
   • Used for communications
   • Don't spread out as much as radio waves
     • Can use be used to beam signals from one place to another.

6. Radiowaves

   • Longer in wavelength and lower in frequency than microwaves
   • Radiowaves are used to carry radio, TV and mobile phone signals.
   • Can be used instead of cables in computers
     • ie. bluetooth

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