Question 366: Ray Optics

Question

A person can see clearly objects only when they lie between 50 cm and 400 cm from his eyes . In order to increase the maximum distance of distinct vision to infinity, the type and power of the correcting lens, the person has to use. will be

Accepted Answer

Given u = 400 cm = 4 m
v = $$\infty $$  and f = ?
Since, $${1 \over f} = {1 \over v} - {1 \over u}$$
= $${1 \over \infty } - {1 \over 4}$$
so,  f = Ã¢ÂÂ 4 m
Hence, lens will be concave.
Now P = $${1 \over f}$$ = $${1 \over { - 4}}$$ = - 0.25 D

Answer

convex, + 2.25 diopter

Answer

concave, $$-$$0.25 diopter

Answer

concave, $$-$$0.2 diopter

Answer

convex, + 0.15 diopter

Ray Optics

A person can see clearly objects only when they lie between 50 cm and 400 cm from his eyes . In order to increase the maximum distance of distinct vision to infinity, the type and power of the correcting lens, the person has to use. will be

Choose the correct answer: