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A convex lens of focal length… (Class 10 Science 2026, Q30)

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ScienceCBSE Class 10 · Board exam 2026, set 31/1/1 · 1 mark · MCQ

CBSE Class 10 Science 2026: question 30

Set in the CBSE Class 10 board exam of 2026, paper 31/1/1, section C, question 30, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q30 · 1 mark · MCQLight – Reflection and Refraction

A convex lens of focal length 15 cm, is forming a real image. If the size of image is same as the size of object, then position of object and position of image will be, respectively:

  1. (A) cm and cm from lens
  2. (B) cm and cm from lens
  3. (C) cm and cm from lens
  4. (D) cm and cm from lens

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

Hints

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

Hint 1

Where must the object be for a real image of the same size?

Hint 2

The object is on the left (negative) and the real image on the right (positive).

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 convex lens forms a real image of the same size when the object is at . The image is then at .

  2. cm. By the sign convention, cm and cm. Check: . Correct option: (C).

    1 mark

Answer: −30 cm and +30 cm, option (C)

Where the marks are

  • Object at 2F₁ and image at 2F₂ with correct signs (1 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 31/1/1: 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.