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OR (Class 10 Science 2023, Q25b)

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ScienceCBSE Class 10 · Board exam 2023, set 31/6/1 · 2 marks · Very short answer

CBSE Class 10 Science 2023: question 25(b)

Set in the CBSE Class 10 board exam of 2023, paper 31/6/1, section B, question 25(b), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q25(b) · 2 marks · Very short answerLight – Reflection and Refraction

OR

  1. (a)

    A ray of light starting from diamond is incident on the interface separating diamond and water. Draw a labelled ray diagram to show the refraction of light in this case.

    1 mark
  2. (b)

    Absolute refractive indices of diamond and water are 2.42 and 1.33 respectively. Find the value of refractive index of water w.r.t. diamond.

    1 mark

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/6/1.

Hints

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

Hint 1

Diamond has the higher refractive index, so light goes from denser to rarer.

Hint 2

The refractive index of medium 2 with respect to medium 1 is n₂/n₁.

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) Ray diagram (in words): Draw a horizontal interface with diamond below and water above, and a dashed normal at the point of incidence. Draw the incident ray in diamond, with an arrow, meeting the interface at angle . Draw the refracted ray in water bending away from the normal, at angle , because water is optically rarer than diamond. Label , , both media and the arrows.

    1 mark

  2. (b)

    ½ mark

  3. ½ mark

Answer: (a) Ray bends away from the normal in water (∠r > ∠i); (b) refractive index of water w.r.t. diamond ≈ 0.55

Where the marks are

  • Correct diagram, ray bending away from normal, with ∠i, ∠r and arrows marked (1 mark)
  • Uses n_wd = n_w/n_d with substitution (½ mark)
  • Answer ≈ 0.55 (½ 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 paper2023 board paper, set 31/6/1: 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.