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?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → +50 cm
For a normal person, the least distance of distinct vision = 25 cm
$∴v=-50cm$ [given]
$\frac{1}{f}=-\frac{1}{50}-(-\frac{1}{25})$
$=\frac{1}{50}$
$f=50cm$