Which of the following is/are responsible for the formation of Rainbow?
(A) Dispersion of light
(B) Interference of light
(C) Reflection of light
(D) Refraction of light
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (C) and (D) only
A rainbow is formed when sunlight passes through raindrops. In the primary rainbow, sunlight is refracted on entering a drop and split into colours, reflected once from the back surface inside the drop, and refracted again on leaving it.
(A) Dispersion of light — Correct. Different colours have different refractive indices in water, so they are bent by different amounts and spread out. This gives the band of colours.
(B) Interference of light — Incorrect. The rainbow is explained fully by ray optics; no superposition of coherent waves is needed to form it.
(C) Reflection of light — Correct. The light is reflected from the inner back surface of the drop, which sends it back towards the observer standing with the Sun behind.
(D) Refraction of light — Correct. Refraction at entry and at exit bends the light and produces the dispersion.
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):
The Rainbow – “The rainbow is an example of the dispersion of sunlight by the water drops in the atmosphere. This is a phenomenon due to combined effect of dispersion, refraction and reflection of sunlight by spherical water droplets of rain.”