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Saturday Science: Make a Rainbow

Ever wonder how a rainbow forms? In this experiment, your family will understand how a rainbow works...by making one yourself! 

Materials

  • Water
  • Mirror
  • Scissors
  • Dark room
  • Flashlight

Process

  1. Position your glass of water on a table and then place the mirror inside it at an angle.
  2. Make sure that the room is completely dark. Close all the curtains and the blinds so it gets pitch dark.
  3. Take the flashlight and aim the light towards the mirror that you placed inside the glass.
  4. Watch a rainbow appear from the angle of your mirror. Adjust the angle of the mirror as you wish!

Results

You've just made your own rainbow, but do you know the explanation behind your creation? A rainbow is an optical phenomenon that appears as a band of colors in an arc, resulting from the refraction of the sun's light rays by the rain. When the sun shines on the droplets of water in the atmosphere, a rainbow, as people see it, is formed.
 
A rainbow displays the colors red, orange, yellow, green, blue, indigo and violet, in that order. Its formation can also be caused by mist, dew, and spray. When light strikes the surface of a water drop, it changes speed, causing it to bend. It is refracted as it enters the water and then refracts again as it leaves the droplet. The outcome is light being reflected in varying angles, creating a rainbow.
 
Light travels in waves where the length of each would depend upon the color. When light retracts, the different colors refract and bend in different amounts as well. This is the reason why we see different colors in a spectrum when there is a rainbow.
 
This experiment is adapted from the activity on the Explorable blog.
 
Want more Saturday Science? See all of our at-home activities on the blog or on Pinterest