Question

a person is unable to see object distinctively placed within 50 cm from his eyes . (a)Name the defect of vision the person is suffering from analysis to possible causes(b) draw a ray diagram to show the defect in the above case (c )mention the type of lens used by him for the correction of the defect and calculate its power assume that near point for the normal eye is 25 cm (d) draw a level diagram for the correction of the defect in the above case

Answer 1

Hypermetropia

for ray diagrams refer ncert

convex lens of power+2D

using xd/x-d

where x is the near point of affected eye

and d is the normal near point

Answer 2

Hii friend,

◆ Answers -
1) Hypermetropia.
Hypermetropia is a condition of the eye where close objects appear blurry but far ones appear clearly.

Causes of hypermetropia -
a) Eyeball is too short
b) Abnormal shape of cornea/lens
c) Refractive index of lens is decreased
d) Focal length of lens in increased

2) [Refer to image attachment for ray diagram]

3) Hypermetropia is managed with providing patients with convex lens (positive leans).

Focal length of lens -
P = 1/f = 1/v - 1/u
P = 1/-0.5 - 1/-0.25
P = +2 D

4) [Refer to image attachment for ray diagram]


Hope that was useful...