NEET Physics Question - Ray Optics - Refraction by Spherical Surfaces

Assertion (A): Rainbow is an example of the dispersion of sunlight by the water droplets.

Reason (R): Light of shorter wavelength is scattered much more than light of larger wavelength.

(1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)

(2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)

(3) (A) is true but (R) is false

(4) Both (A) and (R) are false

Solution:

Rainbows are formed due to dispersion and total internal reflection of sunlight by water droplets. Thus, (A) is true.
Rayleigh scattering states that the intensity of scattered light is inversely proportional to the fourth power of its wavelength \((I \propto 1/\lambda^4)), meaning shorter wavelengths (blue, violet) are scattered more than longer wavelengths (red). Thus, (R) is true.
However, (R) explains scattering, which is distinct from dispersion (dependence of refractive index on wavelength) responsible for the separation of colors in a rainbow. So, (R) does not explain (A).

Rankers Physics

Rainbow Dispersion

Solution:

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