This hands-on physics investigation lets students explore the wave nature of light using everyday objects. In this activity, students use CDs and DVDs as diffraction gratings to measure the spacing of tracks on the discs. By shining lasers onto the discs and observing diffraction patterns, students gain an intuitive understanding of interference and how information density differs across optical storage media.
Grade Range: 8 to 12
Duration: 1 – 2 Hours
Supplies:
- Laser Blox in Red/Green/Violet
- CD
- DVD
- Blu-ray Disc (optional)
- Painter’s tape
- Polar graph paper (included in handout)
NGSS Connections
- PS4.A: Wave Properties – Waves can add or cancel as they overlap, affecting amplitude (interference).
- PS4.B: Electromagnetic Radiation – The spacing of tracks on a CD or DVD causes light to diffract, creating patterns related to wavelength.
- Science and Engineering Practices – Planning and carrying out investigations; using mathematics to analyze patterns.
- Crosscutting Concepts – Cause and effect relationships (how wavelength and track spacing determine diffraction).
