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प्रश्न
A student is unable to see clearly the words written on the blackboard placed at a distance of approximately 4 m from him. Name the defect of vision the boy is suffering from. Explain the method of correcting this defect.
Draw ray diagram for the:-
(i) defect of vision and also
(ii) for its correction.
A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected?
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उत्तर
As the student is not able to clearly see the words written on the blackboard that is at a distance of approximately 4 m from him, the student is suffering from the defect called myopia or near-sightedness. A myopic eye has its far point nearer than infinity. It forms the image of a distant object in front of its retina. To correct a myopic eye, concave lens of a suitable focal length is used. The image is allowed to form at the retina by using a concave lens of suitable power.
(i) A myopic eye
(ii) Correction of myopia using concave lens
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संबंधित प्रश्न
Name the defect of vision in a person:
whose near point is more than 25 on away.
A student sitting in the last row of the class-room is not able to read clearly the writing on the blackboard.
How can this defect by corrected?
Name the defect of vision which can be corrected by a converging lens. Show clearly by a ray diagram how the lens corrects the defect.
A person suffering from the eye-defect myopia (short-sightedness) can see clearly only up to a distance of 2 metres. What is the nature and power of lens required to rectify this defect?
What is long-sightedness? State the two causes of long-sightedness (or hypermetropia). With the help of ray diagrams, show:
(i) the eye-defect long-sightedness.
(ii) correction of long-sightedness by using a lens.
Though a woman can see the distant object clearly, she cannot see the nearby objects clearly. She is suffering from the defect of vision called:
(a) long-sight
(b) short-sight
(c) hind-sight
(d) mid-sight
The defect of vision in which the eye-lens of a person gets progressively cloudy resulting in blurred vision is called:
(a) myopia
(b) presbyopia
(c) colourblindness
(d) cataract
Write whether the following is true or false:
A convex lens is used for correcting myopia.
Give Reason:
Why do we see clearly in the central region of the retina?
Correlate the given sequence:
Hypermetropia : Convex lens : ______ : Concave lens
