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प्रश्न
What are the two most common defects of vision (or defects of eye)? How are they corrected?
उत्तर
The two most common defects of vision (or defects of the eye) are the following.
1. Myopia (short-sightedness or near-sightedness): Myopia is an eye defect because of which a person cannot see faraway objects clearly but can see nearby objects normally. By using spectacles with concave lenses, myopia can be corrected, as a concave lens reduces the converging power of the eye lens and therefore forms the images of faraway objects on the retina of the myopic eye.
2. Hypermetropia (long-sightedness or far-sightedness): Hypermetropia is an eye defect because of which a person cannot see nearby objects clearly but can see faraway objects normally. By using spectacles with convex lenses, hypermetropia can be corrected, as a convex lens increases the converging power of the eye lens and therefore forms the images of nearby objects on the retina of the hypermetropic eye.
The two most common defects of vision (or defects of the eye) are the following.
1. Myopia (short-sightedness or near-sightedness): Myopia is an eye defect because of which a person cannot see faraway objects clearly but can see nearby objects normally. By using spectacles with concave lenses, myopia can be corrected, as a concave lens reduces the converging power of the eye lens and therefore forms the images of faraway objects on the retina of the myopic eye.
2. Hypermetropia (long-sightedness or far-sightedness): Hypermetropia is an eye defect because of which a person cannot see nearby objects clearly but can see faraway objects normally. By using spectacles with convex lenses, hypermetropia can be corrected, as a convex lens increases the converging power of the eye lens and therefore forms the images of nearby objects on the retina of the hypermetropic eye.
The two most common defects of vision (or defects of the eye) are the following.
1. Myopia (short-sightedness or near-sightedness): Myopia is an eye defect because of which a person cannot see faraway objects clearly but can see nearby objects normally. By using spectacles with concave lenses, myopia can be corrected, as a concave lens reduces the converging power of the eye lens and therefore forms the images of faraway objects on the retina of the myopic eye.
2. Hypermetropia (long-sightedness or far-sightedness): Hypermetropia is an eye defect because of which a person cannot see nearby objects clearly but can see faraway objects normally. By using spectacles with convex lenses, hypermetropia can be corrected, as a convex lens increases the converging power of the eye lens and therefore forms the images of nearby objects on the retina of the hypermetropic eye.v
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संबंधित 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.
Name any two defects of vision which can be corrected by using spectacles.
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?
Explain with the help of labelled ray-diagram, the defect of vision called hypermetropia, and hot it is corrected by a lens.
Describe the mechanism of focusing the image of a distant object in your eye when you raise your head after reading a book.
Have a look at the posture of this girl who is reading a book and answer the questions which follow:
Name the problem she is facing.
Observer the following diagram and answer the questions.
a) Which eye defect is shown in this diagram?
b) What are the possible reasons for this eye defect?
c) How this defect is corrected, write it in brief?
Rewrite the following table so as to match second and third column with first column.
|
Column I
|
Column II
|
Column III
|
|
(i) Myopia
|
Old age problem
|
Bifocal lens
|
|
(ii) Presbyopia
|
Nearsightedness
|
Concave lens.
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Mention, if the following statement is True or False
Hypermetropia is a defect of the eye caused due to the eyeball elongation
Given below is a diagram showing a defect of vision. Name the defect of vision and draw an accurately labelled diagram to correct this defect.
