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

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Q: 102 (IAS/2000)
When a CD (Compact Disc used in audio and video systems) is seen in sunlight, rainbow like colours are seen. This can be explained on the basis of the phenomenon of

question_subject: 

Science

question_exam: 

IAS

stats: 

0,38,58,47,8,3,38

keywords: 

{'cd': [0, 2, 0, 0], 'compact disc': [0, 2, 0, 0], 'sunlight': [0, 0, 1, 0], 'colours': [0, 2, 4, 9], 'refraction': [0, 0, 1, 0], 'diffraction': [0, 2, 2, 9], 'reflection': [1, 1, 2, 19], 'video systems': [0, 1, 0, 0], 'phenomenon': [3, 4, 7, 15]}

The phenomenon of seeing rainbow-like colours on a CD under sunlight can be explained based on refraction, diffraction, and transmission – which is the correct answer (option 4). Here`s a basic explanation of each process:

1. Refraction: When light hits the CD, it enters the device at an angle different from the one it had prior to contact, causing the light to "bend." This bending separates the white light into its constituent color spectrum (much like a rainbow).

2. Diffraction: As the light hits the microscopic grooves on the CD, it spreads out and interferes with itself. This interference pattern creates the different colors we see.

3. Transmission: The light also passes through the CD, and this process can contribute to the final colours observed.

The other three options involving only two of these phenomena would not fully cover the broad range of colors seen on a CD in sunlight. For instance, reflection alone (options 1 and 2) wouldn`t cause colour dispersion. Similarly, option 3 lacks refraction, which is crucial for light dispersion.