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Question
Name the common defects of the eye.
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Solution
Common defects of the eye:
(i) Near or short-sightedness (Myopia)
(ii) Far or long-sightedness (Hypermetropia)
(iii) Astigmatism.
(iv) Presbyopia.
(v) Night blindness.
(vi) Colour blindness.
(vii) Squint.
(viii) Cataract.
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Name the body part with which the terms myopia and hypermetropia are connected.
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Give Reason:
Deficiency of vitamin A causes night blindness.
Explain the Term: Cataract
Observe the given below the figure, correct it and explain and write about the concept depicted in this figure.
Myopia and hypermetropia can be corrected by:
A person is unable to see clearly a poster fixed on a distant wall. He however sees it clearly when standing at a distance of about 2 m from the wall.
- Draw ray diagram to show the formation of image by his eye lens when he is far away from the wall.
- List two possible reasons of this defect of vision.
- Draw ray diagram to show the correction of this defect using appropriate lens.
