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Explain the phenomenon of… (Class 10 Science 2026, Q36)

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ScienceCBSE Class 10 · Board exam 2026, set 31/4/1 · 3 marks · Short answer

CBSE Class 10 Science 2026: question 36

Set in the CBSE Class 10 board exam of 2026, paper 31/4/1, section C, question 36, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q36 · 3 marks · Short answerThe Human Eye and the Colourful World

Explain the phenomenon of rainbow formation in the sky. Draw the labelled ray diagram in support of your explanation.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/4/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Think of each raindrop as a tiny prism.

Hint 2

Light undergoes three processes inside the drop: two refractions and one reflection.

Hint 3

In your diagram, show where the white light splits and label at least the red and violet rays.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. A rainbow is a natural spectrum seen in the sky after a shower, always on the side opposite to the Sun. It is caused by dispersion of sunlight by tiny water droplets in the atmosphere, which act like small prisms.

    1 mark

  2. In each droplet, sunlight is first refracted and dispersed on entering. The light is then internally reflected at the back surface of the drop. Finally it is refracted again as it comes out. The colours are separated, so red and violet emerge at different angles and reach the observer to form the bands of the rainbow.

    1 mark

  3. Labelled diagram: a spherical raindrop with a ray of sunlight entering it. The ray splits into colours at the first refraction, is internally reflected at the back of the drop, and is refracted again on emerging. Label the incoming sunlight, the raindrop, internal reflection, and the emergent red and violet rays.

    1 mark

Answer: Rainbow is formed by dispersion of sunlight by raindrops: refraction with dispersion, then internal reflection, then refraction again on leaving the drop; seen opposite the Sun.

Where the marks are

  • Rainbow caused by dispersion of sunlight by water droplets acting as prisms (1 mark)
  • Sequence: refraction + dispersion, internal reflection, refraction on emergence (1 mark)
  • Correct labelled ray diagram of a raindrop showing red and violet rays (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from The Human Eye and the Colourful World, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 31/4/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.