Skip to content

A person uses lenses of +2.0… (Class 10 Science 2025, Q32)

questionbuddy.in/q/cbse-10-science-2025-31-6-1-q32-person-uses-lenses-power-his

ScienceCBSE Class 10 · Board exam 2025, set 31/6/1 · 3 marks · Short answer

CBSE Class 10 Science 2025: question 32

Set in the CBSE Class 10 board exam of 2025, paper 31/6/1, section C, question 32, for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q32 · 3 marks · Short answerThe Human Eye and the Colourful World

A person uses lenses of +2.0 D power in his spectacles for the correction of his vision.

  1. (a)

    Name the defect of vision the person is suffering from.

    0 marks
  2. (b)

    List two causes of this defect.

    0 marks
  3. (c)

    Determine the focal length of the lenses used in the spectacles.

    0 marks

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 31/6/1.

Hints

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

Hint 1

A positive power means which type of lens, and which defect does that lens correct?

Hint 2

Power in dioptre is the reciprocal of focal length in metres.

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) The positive power shows a convex (converging) lens, so the defect is hypermetropia (far-sightedness).

    1 mark

  2. (b) Cause 1: the eyeball has become too small (shortened).

    ½ mark

  3. (b) Cause 2: the focal length of the eye lens is too long, i.e. the lens has become less converging.

    ½ mark

  4. (c)

    ½ mark

  5. m cm (convex lens)

    ½ mark

Answer: (a) Hypermetropia; (b) eyeball too short, focal length of eye lens too long; (c) f = +0.5 m (+50 cm)

Where the marks are

  • Names hypermetropia (1 mark)
  • Two causes (½ × 2 = 1 mark)
  • Uses f = 1/P (½ mark)
  • f = +0.5 m (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 31/6/1: 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.