When a compact disc is illuminated by a source of white light, coloured lines are observed. This is due to

Options

A. (a) diffraction
B. (b) dispersion
C. (c) interference
D. (d) refraction

Answer

A

Explanation

Diffraction is the process of bending and spreading of waves when they meet an obstruction. Also diffraction grating is a reflecting or transparent substance whose surface contains fine parallel grooves or rulings that are equally spaced. When light is incident on grating coloured pattern are formed due to diffraction. When a compact disc is illuminated, then coloured lines are observed because as one surface of the CD has many small pits in the plastic, arranged with concentric rings, that surface has a thin layer of metal applied to make the pits more visible. These pits function as diffraction gratings.