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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
A student suffering from myopia is not able to see distinctly the objects placed beyond 5 m. List two possible reasons due to which this defect of vision may have arisen. With the help of ray diagrams, explain
(i) why the student is unable to see distinctly the objects placed beyond 5 m from his eyes.
(ii) the type of the corrective lens used to restore proper vision and how this defect is corrected by the use of this lens.
(b) If, in this case, the numerical value of the focal length of the corrective lens is 5 m, find the power of the lens as per the new Cartesian sign convention
What are the two most common defects of vision (or defects of eye)? How are they corrected?
Explain with the help of labelled ray-diagram, the defect of vision called hypermetropia, and hot it is corrected by a lens.
A person can read a book clearly only if he holds it at an arm's length from him. Name the defect of vision:
if the person is a young man
Which part of the eye is grafted in a needy patient from a donated eye?
Choose the correct answer :
Presbyopia is a disease of _____________
Give Reason:
Older people require glasses to read and write.
Choose the Odd One Out:
Observe the figure whether it is correct or not and explain the phenomenon.
