Formation of a rainbow: Which phenomena are essential? Sunlight falls on raindrops; identify the correct combination from the listed phenomena. Choose the correct option.

Concept

• A primary rainbow forms due to refraction at entry, internal reflection inside the drop, and dispersion (wavelength-dependent refraction).

NoteThe list uses “diffusion”; the physically relevant term is dispersion. Among the listed choices, the best correct pair is refraction + internal reflection.

Final AnswerRefraction and internal reflection