Question

The clear sky appears blue because
(a) blue light gets absorbed in the atmosphere.
(b) ultraviolet radiations are absorbed in the atmosphere.
(c) violet and blue lights get scattered more than all other colours
by the atmosphere.
(d) light of all other colours is scattered more than the violet and
blue colour lights by the atmosphere.

NCERT Class X
Science - Exemplar Problems

Chapter_SAMPLE QUESTION PAPER-I

Answer 1

The clear sky appears blue because (c) violet and blue lights get scattered more than all other colors by the atmosphere.

Why does the sky seem blue?

• Rayleigh scattering, a phenomenon, is what gives the sky its blue color.
• The electromagnetic radiation (of which light is a kind) that is scattered by particles with a considerably shorter wavelength is referred to as this scattering.

About Rayleigh scattering:

• Rayleigh scattering is the primarily elastic scattering of light or other electromagnetic radiation by particles considerably smaller than the wavelength of the radiation. It is named after the 19th-century British scientist Lord Rayleigh.
• Every photon moves at the speed of light, c, as it passes through a substance.
• The transmitted wave, however, is out of phase with the originating (free-space) wave due to Rayleigh scattering.
• As the light passes through the medium, it is dispersed several times.

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