CD Rainbow Activity

A simple yet exciting indoor activity to learn about light and colour at home or at school.

You will need:

CD / paper / stickytape / pencil or pen / scissors / torch

1. Trace a CD onto paper and cut out circle
2. Fold circle in half and in half again
3. Cut shapes out of your circle
4. Stickytape your paper onto the CD
5. Shine torch onto CD and reflect on wall

QUESTIONS TO DISCUSS

  • What shapes and colours can you see?

  • Does this change if you move the CD?

  • Where else have you seen rainbows and rainbow colours?

  • Why does putting your snowflake on the CD change the patterns? Try the activity without the paper to compare.

HOW DOES IT WORK?

A CD is a mirrored surface with spiral tracks that are evenly spaced. These tracks separate white light into all the colours that make it up. The colours from the torch light are reflected to your eye from the mirror of the CD, producing a rainbow effect. The colours you see reflecting from the CD are “interference colours”, like the moving colours you see on a bubble. The unique shapes appear because your paper snowflake blocks some of the light.

Credit to Buggy and Buddy for this fabulous STEM activity.

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