Question

Assertion: The clouds in the sky generally appear to be white in colour.
Reason: Diffraction due to clouds is efficient in equal measure at all wavelengths.
A. Both assertion and reason are true and the reason correctly explains the assertion.
B. Both assertion and reason are true but the reason doesn’t explain the assertion correctly.
C. Assertion is true but reason is false.
D. Assertion is false but reason is true.
E. Both the assertion and the reason are false.

Answer 1

Hint: The size of the particles in the clouds is very large as compared to the wavelength of the incident light from the sun. Due to which diffraction/scattering of light hardly happens. Therefore, all the rays reflected are seen white. Hence, clouds normally appear to be whitish in colour.

Complete step by step answer:
Let us first discuss the terms diffraction and scattering of light.
The phenomenon in which the bending of light waves around the edges or corners of an obstacle or aperture happens is known as diffraction of light.
When light passes through a medium in which the size of the particles present in it is of the order of wavelength of light, then light striking these particles deviates in different directions. This phenomena is known as scattering of light.
The size of the particles in the clouds is very large as compared to the wavelength of the incident light from the sun. Due to which diffraction/scattering of light hardly happens. Therefore, all the rays reflected are seen white. Hence, clouds normally appear to be whitish in colour.
Therefore, the assertion is true but reason is false.
Hence, option C is correct.

Note: Apart from the clouds there many such daily life examples of scattering of light such as the red colour of signals of danger, black colour of sky in the absence of atmosphere, red colour of sky at the time sunrise and sunset, the human eye is most sensitive to yellow colour, etc.