Distinguish between myopia and hypermetropia. Draw diagrams to show how these defects can be corrected by using suitable lenses..
Answers
Answer:
1) Myopia: In this defect, human eye can see nearby objects distinctly but is unable to see distant objects clearly.
Image of distant object is formed in front of retina. Eye ball is lengthened or lens is curved. This defect is corrected using concave lens.
This defect can be corrected by using a concave lens of suitable power. A concave lens of suitable power will bring the image back on to the retina and thus the defect is corrected.
2) Hypermetropia: In this defect human eye can see distant objects distinctly but is unable to see nearby objects clearly. Image of nearby objects falls behind retina.
Eye ball is shortened or lens is flattened. This defect is corrected using convex lens.
This defect can be corrected by using a convex lens of appropriate power. Eye-glasses with converging lenses provide the additional focussing power required for forming the image on the retina.
Answer:
Hypermetropia
It is a type of eye disease in which the person is unable to see the objects placed near to him. It is also called long sightness. In this the image is formed behind the retina. Convex lens is used to correct it.
Myopia
It is a type of eye problem in which a person is unable to see the objects placed far to him. It us also called near sightness. In it the image us formed in front of retina. Concave lens is used to correct it.
