Question

Noopor needs a lens of power - 4.5D for correction of her vision.

What is the focal lens and the nature of the corrective leans?

Answer 1

As its power is negative its focal length is also negative. We know that concave lens has a negative focal length. Therefore he needs a concave lens for correction. Thus he is suffering from myopia.

f = 1/P
= 1/-4.5
= -10/45
= -0.2222 m
= -22.2 cm
Thus he needs a concave lens of focal length 22.2 cm.