Nooper needs a lens of power `- 4.5 D` for correction of her vision.
(a) What kind of defect in vision is she suffering from ?
(b) What is the focal length and nature of corrective lens ?
( c) Draw ray diagrams showing the defected eye and correction for the defect.
(d) What are the causes of this defect ?

Explanation

(a) As the power of lens is negative, she must be suffering from myopia.
(b) Power, P =-4.5 D, focal length, f = ?
`P = (1)/(f)`
`implies f = (1)/(P)=(1)/(-4.5) = - 0.222m = - 22.2 cm`
(c ) The nature of the corrective lens is concave or divergent.