A person can see clearly object only when they lie between 50 cm to 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

Question

A person can see clearly object only when they lie between 50 cm to 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 (A) Convex, +2.25D (B) Concave, -0.25D (C) Concave, -0.2D (D) Convex, +0.15D

Tardigrade Admin · Accepted Answer

The maximum distance of distinct vision = 400cm . So the image of the object at infinity is to be formed at 400cm . Use lens formula (1/v)-(1/u)=(1/f) (1/- 400)-(1/∈ fty)=(1/f) P=-0.25 D

Q. A person can see clearly object only when they lie between $50 c m$ to $400 c m$ 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

Convex, $+ 2.25 D$

Concave, $- 0.25 D$

Concave, $- 0.2 D$

Convex, $+ 0.15 D$

The maximum distance of distinct vision = $400 c m$ . So the image of the object at infinity is to be formed at $400 c m$ .
Use lens formula
$\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$
$\frac{1}{- 400} - \frac{1}{\in f t y} = \frac{1}{f}$
$P = - 0.25 D$

Q. A person can see clearly object only when they lie between 50cm to 400cm 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

Convex, +2.25D

Concave, −0.25D

Concave, −0.2D

Convex, +0.15D