Rainbow Snowflake

This activity help kids understand diffraction and learn where rainbows come from.

Materials

  • Blank or old CD
  • Paper
  • Scissors
  • Tape
  • Pencil
  • Light source (like sunlight)

Directions

  1. Take your CD and shine a light on it. Make sure that you have a surface for the light to reflect onto.
  2. Notice the shape of the rainbow. How is it similar to the shape of the CD?
  3. Next, use the scissors and paper to make a paper snowflake.
  4. Tape the snowflake onto the CD and shine the light on it.
  5. How is the shape different? What does it have to do with the shape of your CD?

Explanation

The sun may look yellow, but the light we receive from it is actually white light. White light is a combination of every color in the rainbow and can be separated into individual colors. For example, when white light hits an apple, red is the only color that gets reflected. So how do we get every color to be separated and reflected?  A CD is a mirrored surface with spiral tracks or pits. These tracks are evenly spaced and diffract the sunlight (separating the colors). Because the CD’s surface is mirrored, the light is reflected to your eye. The paper is blocking some light rays from the CD, but letting others through creating all kinds of patterns and designs!