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Study the diagram given… (Class 10 Science 2024, Q31a)

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ScienceCBSE Class 10 · Board exam 2024, set 31/5/1 · 3 marks · Short answer

CBSE Class 10 Science 2024: question 31(a)

Set in the CBSE Class 10 board exam of 2024, paper 31/5/1, section C, question 31(a), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q31(a) · 3 marks · Short answerThe Human Eye and the Colourful World

Study the diagram given below and answer the questions that follow.

  1. (i)

    Name the defect of vision depicted in this diagram stating the part of the eye responsible for this condition.

    1 mark
  2. (ii)

    List two causes of this defect.

    1 mark
  3. (iii)

    Name the type of lens used to correct this defect and state its role in this case.

    1 mark

Figure in the paper: Eye diagram: an object placed on the horizontal principal axis at points N and N' on the left. Light rays from these points pass through the eye lens and converge at a point in front of the retina, shown at the right side of the eyeball, with the eye lens drawn inside the eyeball outline. See it in the official paper.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 31/5/1.

Hints

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

Hint 1

Points N and N′ mark near points. Which defect makes it hard to see objects close to the eye?

Hint 2

In this defect the eye lens does not converge light strongly enough. Which type of lens adds converging power?

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) The defect is hypermetropia (long-sightedness): a nearby object, at the near point N, is not focused on the retina.

    ½ mark

  2. The part responsible is the eye lens, whose converging power the ciliary muscles cannot increase enough.

    ½ mark

  3. (ii) Cause 1: the focal length of the eye lens is too long.

    ½ mark

  4. Cause 2: the eyeball has become too small (too short).

    ½ mark

  5. (iii) It is corrected with a convex (converging) lens of suitable power.

    ½ mark

  6. Role: the convex lens provides the additional focusing (converging) power needed to form the image of a nearby object on the retina.

    ½ mark

Answer: (i) Hypermetropia, eye lens/ciliary muscles; (ii) focal length of eye lens too long, eyeball too small; (iii) convex lens, which gives the extra converging power to focus the image on the retina.

Where the marks are

  • Names hypermetropia (½ mark)
  • Names the eye lens / ciliary muscles as responsible (½ mark)
  • States that the focal length of the eye lens is too long (½ mark)
  • States that the eyeball is too small (½ mark)
  • Names a convex / converging lens (½ mark)
  • States that it supplies the additional converging power to form the image on the retina (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 paper2024 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.