UPSC Prelims 2000·GS1·science-and-technology·science and technology

When a CD (Compact Disc used in audio and video systems) is seen in sunlight, rainbow like colours is seen. This can be explained on the basis of the phenomenon of

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Last updated 23 May 2026, 3:31 pm IST
  1. Areflection and diffraction
  2. Breflection and transmission
  3. Cdiffraction and transmission
  4. Drefraction, diffraction and transmissionCorrect

Explanation

The rainbow like colors on a CD are primarily caused by three phenomena working together. First, the surface of a CD contains millions of tiny pits and tracks that act as a diffraction grating. When sunlight hits these tracks, it undergoes diffraction, which means the light waves bend and spread out. Second, these diffracted light waves are reflected back to our eyes from the shiny aluminum layer of the disc. Third, as the light travels through the thin protective plastic coating of the CD, transmission occurs. The combination of diffraction and reflection causes different wavelengths of light to interfere with each other, separating white light into its component colors. Therefore, the most comprehensive explanation involves refraction, diffraction, and transmission.
science-and-technology: When a CD (Compact Disc used in audio and video systems) is seen in sunlight, rainbow like colours is seen. This can be
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