Question

Anupama needs a lens of power -4.5D for correction of her vision.
1. What kind of defect in vision she is suffering from?
2. What is the focal length and nature of the corrective lens?
3. What are the causes of this defect?

Answer 1

she is suffering from Myopia/near-sightedness.

D=1/f

f=1/-4.5

f=-0.22m

nature of lens is concave lens/diverging lens.

causes:

1) excessive curvature of eye lens

2) elongation of eye ball

Answer 2

1. She is suffering from myopia.

2. we know that ,

P = 1/f

f = 1/P

f = 1/-4.5

f =0.2m

Therefore, it's a concave lens of 0.2m.

3. It is caused due to :

Excessive curvature of the eye lens or elongation of the eyeball.

Hope this answer helps u..