Question

When a compact disc (CD) is illuminated by small source of white light coloured band are observed. This is due to

• A. Interference
• B. Scattering
• C. Reflection
• D. Diffraction

Answer 1

The Correct Option is D

Diffraction refers to the phenomenon where waves bend or spread as they encounter obstacles or pass through openings. In the context of a CD, its surface features a series of closely spaced tracks or grooves. When white light strikes the CD, these grooves function as diffracting elements. They cause the light to spread out and interact with one another, leading to interference. This interference produces the appearance of colored bands or a rainbow-like pattern. Therefore, the correct answer is (D) diffraction.

Answer 2

The phenomenon of diffraction is responsible for the colored bands observed when a compact disc (CD) is illuminated by a small source of white light. Diffraction occurs when a wave encounters an obstacle or a slit that is comparable in size to its wavelength. In the case of a CD, the surface of the disc contains a series of closely spaced microscopic grooves or tracks. When white light illuminates the CD, these grooves act as diffracting elements.

The diffracted light waves interfere with each other, resulting in both constructive and destructive interference. This interference causes different wavelengths (colors) of light to be reinforced or canceled out at different angles, creating the observed colored bands on the CD surface. Therefore, the correct answer is diffraction.