Question

A person near point of vision is $100cm$. Then, the power of lens he must wear so as to have normal vision is

• A. -3 D
• B. + 3 D
• C. -1 D
• D. +1 D

Answer 1

Answer: (B)

$f=\frac{yD}{y-D}=\frac{100\times 25}{100-25}$
$=\frac{100}{3}cm=\frac{1}{3}m$
$P=\frac{1}{f}=+3D$