• Question: why are there so many colours in a rainbow?

    Asked by thefemaleboss26 to Amy, Karen, Sarah, Vijay, Will on 18 Jun 2012. This question was also asked by olaa, meg123, niamhcarr.
    • Photo: Will Reynolds

      Will Reynolds answered on 18 Jun 2012:

      Light is made up of lots of different colours that have different energies. When we see all these colours together it is white. Light that comes from the sun is almost white (but a little bit yellow!). Rainbows form when there are lots of water droplets in the air, like after rain or in a waterfall. Light travels slower through water than air so when it comes through the water droplets it is refracted into lots of different colours, the six main ones we can see with our eyes being red, yellow, orange, green, blue and purple. The song about the colours of the rainbow has seven because the number six used to be asociated with the devil and people didnt lilke it so they split purple into indigo and violet!

    • Photo: Karen Reed

      Karen Reed answered on 18 Jun 2012:

      White light is the collection of all the different wavelengths of light reaching the eye at the same time. Raindrops can bend – or refract – the different wavelendths as they travel through the rain drop, so when the come out the other side they are scattered apart from each other. Becuase then the different wavelenths are not all together you can see the different colours.

    • Photo: Amy Birch

      Amy Birch answered on 19 Jun 2012:

      Hi thefemaleboss26,
      Great answers by Will & Karen here!
      I just wanted to add a few interesting facts – we see colours based upon the stimulation of photoreceptors in the eye that transmit a signal to the brain. Each individual person’s photoreceptors will respond slightly differently to different wavelengths in light and therefore different people will actually slightly different colours in the rainbow!
      Also, people who are colourblind only see a small subset of the colours of a rainbow compared to people with normal colour vision.
      Great question! 🙂

    • Photo: Sarah Martin

      Sarah Martin answered on 20 Jun 2012:

      Hi boss!

      Great answers to a great question so far! I want to just add a diagram of how water droplets refract light. Because water droplets will release light of different energies at different angles – higher energy light (purple) bends stronger in the droplets than lower energy light (red). That’s why the red band of the rainbow is always at the top (with the largest angle between the sun, the drops and us), with then the higher energy bands orange, yellow, green, blue and finally purple with the highest angle right at the bottom. Check it out!

      🙂 Sarah

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