demonstrations:make_rainbow_with_a_cd
Make Rainbow With a CD
Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required
Categories: Electromagnetic Spectrum and Waves, Light
Alternative titles: Creating Light Patterns with a CD
Summary
This colorful experiment explores how light interacts with the reflective surface of a CD to create rainbow patterns.
Procedure
- Gather materials: a blank or old CD, paper, scissors, tape, and a pencil.
- Find a sunny location where the CD can reflect sunlight onto a blank wall or white poster board.
- Hold the shiny side of the CD toward the sunlight and observe the rainbow reflection on the wall. Note the colors and shapes.
- Trace the CD onto sheets of paper several times and cut out circular pieces.
- Fold and cut these circles into snowflake or geometric designs.
Links
How to make a rainbow colors with a CD - Kids Fun Science:
📄 Rainbow Science: Creating Light Patterns with a CD - Buggy and Buddy: https://buggyandbuddy.com/rainbow-science-create-light-patterns-with-a-cd/
Variations
- Use a flashlight instead of sunlight for indoor exploration.
- Try using colored or translucent paper snowflakes to see how color affects the light patterns.
- Experiment with DVDs or Blu-ray discs and compare the sharpness and color of the reflections.
- Use black paper cutouts to create shadow-based rainbow designs.
Safety Precautions
- Never look directly at the sun while using the CD, only observe the reflection on a surface.
- Supervise young children when using scissors to cut paper.
- Avoid using sharp or cracked CDs that could cause injury.
Questions to Consider
- Why does a CD produce rainbow colors when light hits it? (The CD’s surface has tiny, evenly spaced grooves that act as a diffraction grating, separating white light into its component colors.)
- What happens when you change the angle of the CD? (The reflected light shifts, altering the shape and position of the rainbow.)
- How does adding paper snowflakes change the light pattern? (The paper blocks some light rays, creating new shadow and diffraction patterns.)
- How is this similar to how a prism creates a rainbow? (Both separate white light into its spectrum through diffraction or refraction.)