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A ray of light enters into… (Class 10 Science 2026, Q33)

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ScienceCBSE Class 10 · Board exam 2026, set 31/3/1 · 2 marks · Very short answer

CBSE Class 10 Science 2026: question 33

Set in the CBSE Class 10 board exam of 2026, paper 31/3/1, section C, question 33, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q33 · 2 marks · Very short answerLight – Reflection and Refraction

A ray of light enters into medium B from medium A as shown in the given figure :

  1. (a)

    Which one of these two media is optically denser than the other medium ? Justify your answer.

    0 marks
  2. (b)

    If the speed of light in medium A is and in medium B is , then what is the refractive index of medium B with respect to medium A ?

    0 marks

Figure in the paper: Interface between medium A (below) and medium B (above) drawn as a vertical line with a horizontal normal NN′. The incident ray in A approaches the boundary at a small angle to the normal line and the refracted ray in B bends away from the normal (larger angle). See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/3/1.

Hints

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

Hint 1

Compare the angle of the ray with the normal in A and in B.

Hint 2

Refractive index of medium 2 with respect to medium 1 = speed in medium 1 ÷ speed in medium 2.

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) Medium A is optically denser. The ray going from A into B bends away from the normal NN′, and light bends away from the normal only when it passes from a denser to a rarer medium.

    1 mark

  2. (b) Refractive index of B with respect to A:

    1 mark

Answer: (a) Medium A, since the ray bends away from the normal on entering B; (b)

Where the marks are

  • Identifies A as denser, justified by the ray bending away from the normal (1 mark)
  • Writes (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Light – Reflection and Refraction, one at a time, marked against the answer key and marking points.Back to the full paper2026 board paper, set 31/3/1: 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.