When white light enters a glass prism, it splits into its constituent colours. This is due to:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → different refractive indices for different wavelengths of constituents of white light
The splitting of white light by a prism is dispersion. The refractive index of glass depends on the wavelength: it is largest for violet and smallest for red. Each colour is therefore deviated by a different angle, violet the most and red the least, and the colours emerge separated.
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), but it is still in the CUET 2026 syllabus, so do not skip it.
NCERT (Pre-rationalised edition, 2022-23):
Dispersion by a Prism – “… Dispersion takes place because the refractive index of medium for different wavelengths (colours) is different. For example, the bending of red component of white light is least while it is most for the violet.”