CBSE Class 10 Science 2017 · Paper 31/1/1/C · Question 7

The Human Eye and the Colourful World 3 marks Medium

Varun instead of copying from the black board use to copy regularly from the note book of his friend, Sudhir with whom he sat on the same desk. Sudhir told the teacher about it. The teacher asked Varun to get his eyes checked by a doctor and explained to whole class the reason why Varun copied from Sudhir’s notebook.

(i)What in your view, is wrong with Varun’s eyes and how can it be corrected ?
(ii)If the doctor prescribes Varun to use lenses of power $- 0.5$ D, write the type of these lenses.
(iii)Write the values displayed by Sudhir and his teacher.

Answer

Varun has myopia, corrected by a concave lens; $- 0.5$ D lenses are concave; Sudhir and the teacher show care and concern.

(i) Varun is suffering from myopia (near-sightedness): he sees nearby objects, such as the notebook on his desk, clearly, but distant objects, such as the blackboard, look blurred, because the image of a distant object is formed in front of the retina. It can be corrected by using spectacles with a concave (diverging) lens of suitable power. (ii) The power is negative, so these are concave (diverging) lenses; their focal length is

f = \frac{1}{- 0.5}

= - 2

m. (iii) Sudhir: concern and care for his friend, and a sense of responsibility — he reported the problem so that Varun could get help. The teacher: care and sensitivity towards the student, and a scientific attitude — instead of punishing Varun, the teacher found the real cause, sent him for an eye check-up and made the whole class aware of it.

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CBSE Class 10 Science 2017 · Paper 31/1/1/C · Question 7

Answer

From the board papers

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