Question

A person needs a lens of power -4.5d for correcting his vision. name the defect of vision he is suffering from?what is the focal length of the corrective lens? What is the nature of the corrective lens

Answer 1

He is suffering from a defect called myopia.

We know,
$P = \frac{1}{f}$

- 4.5 D = $\frac{1}{f}$

   f       = $\frac{-1}{4.5}$

 ∴ f = 0.2 m = 20 cm