Question

A person suffering from a defect of vision uses a corrective lens of power 4D . (a) Name the defect of vision and draw the ray diagrams for the defect and it's correction .
(b) Find the nature and focal length of the corrective lens.

Answer 1

à)the person is suffering from hypermetropia as he should use convex lens.
b) pic
c)focal length of the lens=
P=1/F
4D =1/F
F=100/4
F=25.

Answer 2

Answer:

the person is suffering from hypermetropia the corrective lens is convex lens

P=1/f

f=1/P

f=1/4 (meters)

f=0.25m