9 Colour

The Visible Spectrum

visible spectrum

White light is, in fact, a collection of many different colours: each colour is made up of light waves of a different wavelength and frequency to the other waves.

When white light is refracted through a lens or prism the light can be split into the separate colours. This is what happens when light shines through water droplets (rain) to make a rainbow.
A deep blue/violet light gets refracted through a bigger angle (it gets bent more) than the red light. The order in which the colurs are bent is as follows:
Red : Orange : Yellow : Green : Blue : Indigo : Violet

Now answer these questions

  1. White light is made up of many different colours
  2. Which colour is bent the most by a prism ?
  3. Which colour is bent the least by a prism ?
  4. What is the scientific name for bending light waves ?
  5. What does light need to shine through to make a rainbow ?

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Why Objects have a Colour

Everything that we can see must reflect light waves in some way. Most objects also absorb some light waves as well.

If a mixture of coloured light is shone on an object it might absorb all the colours. If any colours are reflected instead then that object will look as if it has the same colour as the reflected light.

Look at the animation of Rudolph and his red hair.
When white light (a mixture of colour) shines on the hair all the colours are absorbed ... apart from the red light. The red light waves are reflected so the hair on Rudolph's head looks red.

If all the light waves are reflected in equal amounts then the object will appear to be white.
However, if all the light waves are absorbed then the object will look black.

Rudolph and his red hair

Now answer these questions

  1. Green leaves reflect mainly what colour light ?
  2. Green leaves absorb mainly what colour light ?
  3. What colour absorbs the most light ?
  4. What colour absorbs the least light ?
  5. What colour reflects the most light ?

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