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Draw ray diagrams to show the… (Class 10 Science 2025, Q31)

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ScienceCBSE Class 10 · Board exam 2025, set 31/1/1 · 3 marks · Short answer

CBSE Class 10 Science 2025: question 31

Set in the CBSE Class 10 board exam of 2025, paper 31/1/1, section C, question 31, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q31 · 3 marks · Short answerLight – Reflection and Refraction

Draw ray diagrams to show the nature, position and relative size of the image formed by a convex mirror when the object is placed (i) at infinity and (ii) between infinity and pole P of the mirror.

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

Hints

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

Hint 1

For a convex mirror, F and C lie behind the mirror.

Hint 2

A ray parallel to the axis reflects as if coming from F; a ray aimed at C comes straight back.

Hint 3

Use dotted lines for extensions behind the mirror.

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. (i) Object at infinity – ray diagram: Draw a convex mirror with its pole P, and mark F and C behind it on the principal axis. Draw two rays parallel to the principal axis striking the mirror. After reflection they diverge. Extend them backwards with dotted lines; they appear to meet at F behind the mirror. Mark arrows on all rays.

    1 mark

  2. (i) Image: at the focus F, behind the mirror; highly diminished (point-sized); virtual and erect.

    ½ mark

  3. (ii) Object between infinity and P – ray diagram: Place object AB in front of the mirror. From A, draw (1) a ray parallel to the axis, which reflects as if coming from F (dotted backwards), and (2) a ray directed towards C, which reflects back along the same path. The dotted extensions meet behind the mirror between P and F at A'. Draw the image A'B' (small, upright). Mark arrows on all rays.

    1 mark

  4. (ii) Image: between P and F, behind the mirror; diminished; virtual and erect.

    ½ mark

Answer: (i) At F behind mirror, highly diminished, virtual, erect; (ii) between P and F behind mirror, diminished, virtual, erect

Where the marks are

  • Correct ray diagram for object at infinity, with arrows (1 mark)
  • Image at F, highly diminished, virtual and erect (½ mark)
  • Correct ray diagram for object in front of the mirror, with arrows (1 mark)
  • Image between P and F, diminished, virtual and erect (½ mark)
  • ½ mark is deducted if arrows are missing

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 31/1/1: 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.