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When do we say that a… (Class 10 Science 2024, Q24)

questionbuddy.in/q/cbse-10-science-2024-31-3-1-q24-say-particular-person-suffering-hypermetropia

ScienceCBSE Class 10 · Board exam 2024, set 31/3/1 · 2 marks · Very short answer

CBSE Class 10 Science 2024: question 24

Set in the CBSE Class 10 board exam of 2024, paper 31/3/1, section B, question 24, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q24 · 2 marks · Very short answerThe Human Eye and the Colourful World

When do we say that a particular person is suffering from hypermetropia ? List two causes of this defect. Name the type of lens used to correct this defect.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 31/3/1.

Hints

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

Hint 1

Hyper- means 'far': which objects can this person see well?

Hint 2

Think about where the image forms (in front of or behind the retina) and what could make that happen.

Hint 3

To pull the image forward onto the retina, you need extra 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. When: A person has hypermetropia (far-sightedness) when he can see distant objects clearly but cannot see nearby objects distinctly. The near point of the eye moves farther away than the normal 25 cm, because light from a nearby object focuses behind the retina.

    ½ mark

  2. Cause 1: The focal length of the eye lens is too long, so the eye lens is not converging enough.

    ½ mark

  3. Cause 2: The eyeball has become too small, so the distance from the lens to the retina is too short.

    ½ mark

  4. Correction: A convex (converging) lens of suitable power is used. It brings the image back onto the retina.

    ½ mark

Answer: Hypermetropia: nearby objects are not seen clearly while far objects are seen clearly. Causes: focal length of eye lens too long; eyeball too small. Correction: convex (converging) lens.

Where the marks are

  • States that nearby objects cannot be seen distinctly while far objects are clear (½ mark)
  • Cause: focal length of eye lens too long (½ mark)
  • Cause: eyeball too small/shortened (½ mark)
  • Names convex/converging lens for correction (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 31/3/1: 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.