If the least distance of distinct vision for a person is 50 cm, what should be the focal length of the reading spectacles for him?

+50 cm

The correct answer is Option (4) → +50 cm

For a normal person, the least distance of distinct vision = 25 cm

$∴v=-50cm$ [given]

$\frac{1}{f}=-\frac{1}{50}-(-\frac{1}{25})$

$=\frac{1}{50}$

$f=50cm$