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(a) A ray of light after… (Class 10 Science 2026, Q36)

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ScienceCBSE Class 10 · Board exam 2026, set 31/5/1 · 3 marks · Short answer

CBSE Class 10 Science 2026: question 36

Set in the CBSE Class 10 board exam of 2026, paper 31/5/1, section C, question 36, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q36 · 3 marks · Short answerLight – Reflection and Refraction

(a) A ray of light after reflection from a concave mirror becomes parallel to its principal axis. Draw a labelled ray diagram to show this.

(b) (i) Differentiate between the virtual images formed by a convex mirror and concave mirror.
(ii) "The value of magnification 'm' for a mirror is –2." Calculate the height of object if the height of image is 20 cm.

  1. (a)

    A ray of light after reflection from a concave mirror becomes parallel to its principal axis. Draw a labelled ray diagram to show this.

    0 marks
  2. (b)(i)

    Differentiate between the virtual images formed by a convex mirror and concave mirror.

    0 marks
  3. (b)(ii)

    "The value of magnification 'm' for a mirror is –2." Calculate the height of object if the height of image is 20 cm.

    0 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 31/5/1.

Hints

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

Hint 1

Which special point must a ray pass through so that after reflection it goes parallel to the axis?

Hint 2

Compare the size of virtual images in the two mirrors.

Hint 3

Magnification = image height ÷ object height; a negative m means an inverted image.

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) Draw a concave mirror with pole , principal focus and centre of curvature on the principal axis. Draw a ray from the object passing through (or directed from) towards the mirror; after reflection it travels parallel to the principal axis. Show arrows on both rays and label , , and the principal axis.

    1 mark

  2. (b)(i) Virtual image by a convex mirror is always diminished and is formed for all positions of the object; virtual image by a concave mirror is enlarged and is formed only when the object lies between and .

    1 mark

  3. (b)(ii) ; image is inverted (since is negative), so cm.

    ½ mark

  4. cm. Height of object = 10 cm.

    ½ mark

Answer: (b)(i) Convex: diminished, for all positions; concave: enlarged, only when object between P and F; (b)(ii) h = 10 cm

Where the marks are

  • Correct labelled ray diagram: ray through F reflects parallel to axis (1 mark)
  • Any one correct difference between virtual images (1 mark)
  • Uses with cm (½ mark)
  • Obtains cm (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 paper2026 board paper, set 31/5/1: 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.