Question

A person cannot see distinctly objects kept beyond $2$ $m$. This defect can be corrected by using a lens of power:

• A. $+0.5D$
• B. $-0.5D$
• C. $+0.2D$
• D. $-0.2D$

Answer 1

Answer: (B)

$-0.5D$

The person mentioned here is suffering from myopia and needs a concave lens to correct the defect.
Given:Cannot see the distinctly beyond $2m$ from the myopic eye.
The required focal length of the lens $\frac{1}{f}=P$
$P=-\frac{1}{2}=-0.5D$
A power of -0.5 Dioptres is required to correct the myopic eye.