Question

A person with a myopic eye cant see objects beyond 1.2 m distinctly . What can be said about the likely size of his eyeball? State the nature of the corrective lens that is needed to restore his proper vision.

Answer 1

MYPOIA :-
Myopia is a type of defect of vision in which the person is able to see the nearby objects clearly but unable to see the far objects. In this type of defect of vision the far point of a person comes near.


CAUSES OF THE MYOPIA:-

☸️ elongation of eyeball
☸️ excessive curvature of cornea


In the defect of vision called as myopia the eyeball increases in size. So, the person with a myopic eye which cannot see distant objects beyond 1.2 metre distinctly has an eyeball which is elongated in size.

CORRECTION OF MYOPIA :-

myopia can be corrected with the help of concave lens of appropriate focal length.

Now,
the myopic eye cannot see the distant objects beyond 1.2 m.
Hence,
The power of the concave lens must be equal to :-
$p = \dfrac{1}{f} \\ \\ p = \dfrac{1}{ - 1.2} \\ \\ p = \frac{ - 10}{12} = \frac{ - 5}{6} = ( - 0.833)$

So,

The myopic eye can be corrected by using a concave lens of power (-0.83) diopter.



RAY DIAGRAM OF MYOPIA :-

Please refer the above photograph for the ray diagram.

Hope this will be helping you.

Thanks!

Answer 2

here is your correct answer