Noopur needs a lens of power -4.5D 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 the corrective lens? c) Draw ray diagrams showing the (a) defected eye and (b) correction for this defect. d) What are the causes of this defect?

a) Noopur is suffering from myopia, also known as nearsightedness. In myopia, distant objects appear blurry, while close objects can be seen more clearly.
b) For myopia correction, a concave lens is needed. The power of the lens is given as -4.5D. The negative sign indicates that it is a concave lens. The focal length (f) of the lens can be calculated using the formula:

f= (-1)/4.5= -0.22 cm,as concave lens.

c) Defective Eye (Myopia):
Parallel rays from a distant object converge in front of the retina, causing a blurry image. The image formed is in front of the retina.

Correction with Concave Lens: Parallel rays are diverged by the concave lens.
The diverged rays appear to come from a virtual focus point, resulting in the formation of a clear image on the retina.
Please note that drawing accurate ray diagrams requires specific measurements and angles, but a basic representation can be made to illustrate the concept.

d) Causes of Myopia:
Eyeball Shape: Myopia is often associated with an elongated eyeball, where the distance from the cornea to the retina is too long. And secondly, Due to excess curvature of eye lens.
Genetics: Family history plays a significant role, and individuals with myopic parents are more likely to develop myopia.

Environmental Factors: Excessive near work, such as reading or using digital devices for extended periods, can contribute to the development and progression of myopia.
It’s important for Noopur to consult an eye care professional for a comprehensive eye examination to determine the exact prescription and appropriate corrective measures. Regular eye check-ups are recommended for the timely detection and management of vision-related issues.