Question

The far point of a myopic person is $80cm$ in front of the eye. What is the nature and power of lens required to correct the problem?

Answer 1

The person is suffering from myopia and hence need a concave lens to correct the defect. The lens should be such that an object at infinity must form its image at the far point.

Hence, $f=-80cm=-0.8m$

The power of the lens can be obtained as:

$P=\frac{1}{f}$

$P=\frac{1}{(-0.8)}=-1.25D$