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प्रश्न
List three common refractive defects of vision. Suggest the way of correcting these defects.
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उत्तर
The three common refractive defects of vision are as follows:-
Myopia (short-sightedness):- It is corrected by using spectacles having concave lenses of appropriate power.
Hypermetropia (far-sightedness):- It is corrected by using spectacles having convex lenses of appropriate power.
Presbyopia:- This defect is corrected using bifocal lenses of appropriate power in which the upper part consists of a concave lens (to correct myopia) and the lower part consists of a convex lens (to correct hypermetropia).
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संबंधित प्रश्न
The kind of lens required to correct Myopia
What are the two most common defects of vision (or defects of eye)? How are they corrected?
The picture given here shows a person wearing 'half-moon' spectacles. What sort of eye-defect do do you think he has? Why are these particular spectacles useful to him?
Select the odd one in the following series:
Endolymph, Tympanic membrane, Semi-circular canal, Blind spot.
Write whether the following is true or false:
A convex lens is used for correcting myopia.
Given below is a diagram depicting a defect of the human eye? Study the same and answer the question that follow :
Name the type of lens used to correct this eye defect.
Explain the Term: Presbyopia
Assertion: Concave mirrors are used as reflectors in torches, vehicle head lights and in search lights.
Reason: When an object is placed beyond the center of curvature of a concave mirror, the image formed is real and inverted.
A person needs a lens of power –4.5 D for correction of her vision.
- What kind of defect in vision is she suffering from?
- What is the focal length of the corrective lens?
- What is the nature of the corrective lens?
