According to Rayleigh's law, the intensity of scattered light varies with wavelength \( \lambda \) as
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \( \propto \displaystyle\frac{1}{\lambda^{4}} \)
Rayleigh's law applies to scattering by particles much smaller than the wavelength of light. The intensity of the scattered light is inversely proportional to the fourth power of the wavelength.
\( \displaystyle I_{\mathrm{scattered}} \propto \frac{1}{\lambda^{4}} \)
So light of shorter wavelength is scattered much more strongly than light of longer wavelength; violet scatters more than red by a factor of about \( (700/400)^{4} \approx 9 \).
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), and it also appears to be out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Scattering of Light – “… Light of shorter wavelengths is scattered much more than light of longer wavelengths. (The amount of scattering is inversely proportional to the fourth power of the wavelength. This is known as Rayleigh scattering).”