A person has a minimum distance of distinct vision as 50 cm . The power of lenses required to read a book at a distance of 25 cm is

Question

A person has a minimum distance of distinct vision as 50 cm . The power of lenses required to read a book at a distance of 25 cm is (A) 3 D (B) 1 D (C) 2 D (D) 4 D

Tardigrade Admin · Accepted Answer

(1/f)=(1/v)-(1/u) =-(2/50)+(1/25)=(-1+2/50) (1/f)=(1/50) ⇒ f=50 cm P=(100/50)=2 D

Q. A person has a minimum distance of distinct vision as $50 c m$ . The power of lenses required to read a book at a distance of $25 c m$ is

3 D

1 D

2 D

4 D

$\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$
$= - \frac{2}{50} + \frac{1}{25} = \frac{- 1 + 2}{50}$
$\frac{1}{f} = \frac{1}{50}$
$\Rightarrow f = 50 c m$
$P = \frac{100}{50} = 2 D$

Q. A person has a minimum distance of distinct vision as 50cm . The power of lenses required to read a book at a distance of 25cm is

3 D

1 D

2 D

4 D

f1​=v1​−u1​ =−502​+251​=50−1+2​ f1​=501​ ⇒f=50cm P=50100​=2D

Q. A person has a minimum distance of distinct vision as $50 c m$ . The power of lenses required to read a book at a distance of $25 c m$ is

$\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$
$= - \frac{2}{50} + \frac{1}{25} = \frac{- 1 + 2}{50}$
$\frac{1}{f} = \frac{1}{50}$
$\Rightarrow f = 50 c m$
$P = \frac{100}{50} = 2 D$