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Draw a ray diagram to show… (Class 10 Science 2025, Q25A)

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ScienceCBSE Class 10 · Board exam 2025, set 31/4/1 · 2 marks · Very short answer

CBSE Class 10 Science 2025: question 25(A)

Set in the CBSE Class 10 board exam of 2025, paper 31/4/1, section B, question 25(A), for 2 marks. Try it first; the hints and our step-by-step solution are below.

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

Draw a ray diagram to show the refraction of a ray of light passing through an equilateral glass prism. Mark the angle through which the emergent ray bends from the direction of the incident ray and also name it.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 31/4/1.

Hints

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

Hint 1

At each face, decide whether the ray goes from rarer to denser or denser to rarer, and bend it accordingly.

Hint 2

Extend the incident and emergent rays until they meet. What is the angle between them called?

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. Ray diagram (described): Draw an equilateral triangle PQR as the prism. A ray EF from the left strikes face PQ at F and bends towards the normal on entering glass. The refracted ray FG travels inside the prism and meets face PR at G. There it bends away from the normal and emerges as ray GH.

    1 mark

  2. Labels: incident ray, refracted ray, emergent ray, the normals at F and G, angle of incidence , angle of refraction , angle of emergence , and the angle of the prism at P.

    ½ mark

  3. Extend the incident ray EF forward and the emergent ray GH backward as dotted lines until they meet. The angle between them, , is marked and named the angle of deviation.

    ½ mark

Answer: Ray bends towards the base at both faces; the angle between the extended incident ray and the emergent ray is the angle of deviation ().

Where the marks are

  • Correct ray diagram of refraction through the prism (1 mark)
  • Correct labelling of rays, normals and angles (½ mark)
  • Marks the angle between incident and emergent directions and names it the angle of deviation (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 paper2025 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.