Question

A person can not see clearlt objects at a distance less than 100 cm. The power of the spectacles required to see clearly objects at 25cm is

Answer 1

Answer:

3D

$\frac{1}{f}$ = $\frac{1}{v}$-$\frac{1}{u}$

$\frac{1}{f} = \frac{1}{-100} - \frac{1}{-25} \\\frac{1}{f} = \frac{-1}{100} - \frac{4}{100} \\\frac{1}{f} = \frac{-3}{100}$

p= $\frac{100}{f} (in cm)$

p = 100 / $\frac{100}{3}$

p = 3D