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Draw a ray diagram to show… (Class 10 Science 2025, Q25b)

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ScienceCBSE Class 10 · Board exam 2025, set 31/3/1 · 2 marks · Very short answer

CBSE Class 10 Science 2025: question 25(b)

Set in the CBSE Class 10 board exam of 2025, paper 31/3/1, 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 answerThe Human Eye and the Colourful World

Draw a ray diagram to show the path of a ray of light falling obliquely on one of the refracting faces of a triangular glass prism and mark the angle of deviation on it.

Figure in the paper: Student to draw a ray diagram of a triangular glass prism with an oblique incident ray striking one refracting face, the refracted ray inside the prism, and the emergent ray; the angle of deviation is to be marked between the extended incident ray and the emergent ray. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 31/3/1.

Hints

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

Hint 1

Light bends towards the normal on entering glass and away on leaving.

Hint 2

Extend the incident and emergent rays to see the angle between them.

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. Diagram: draw triangular prism ABC. Incident ray PE strikes face AB obliquely at E; draw the normal at E. The ray bends towards the normal inside the glass along EF to face AC; draw the normal at F. The ray bends away from the normal and emerges along FS, bending towards the base BC.

    1 mark

  2. Mark arrows on the incident ray, refracted ray and emergent ray to show the direction of light.

    ½ mark

  3. Produce the incident ray forward and the emergent ray backward (dotted) until they meet; the angle between them is the angle of deviation ; mark it.

    ½ mark

Answer: Ray diagram through prism with incident ray, refracted ray, emergent ray bent towards base, and angle of deviation D between extended incident and emergent rays.

Where the marks are

  • Correct diagram with normals and bending at both faces (1 mark)
  • Arrows showing direction of rays (½ mark)
  • Angle of deviation correctly marked (½ 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 paper2025 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.