A man cannot see distinctly less than $15 c m$ and more than $100 c m$ . He uses a concave lens of focal length $- 100 c m$ to see the distant objects clearly. What will be his new near point?

25 c m

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17.64 m

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21.64

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25.74 c m

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Solution

The correct option is B $17.64 m$
According to question:-
f= -100m
v= -15cm
To find:- u.
Solution:-From less formula.
$\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$
$\frac{- 1}{15} - \frac{1}{4} = \frac{- 1}{100}$
$\frac{- 1}{4} = \frac{1}{15} - \frac{1}{100} = \frac{85}{1500}$
$u = \frac{- 1500}{85}$

$u = - 17.64 m$

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A man cannot see distinctly less than 15cm and more than 100cm. He uses a concave lens of focal length −100cm to see the distant objects clearly. What will be his new near point?

The correct option is B 17.64mAccording to question:-f= -100mv= -15cmTo find:- u.Solution:-From less formula.1v−1u=1f−115−14=−1100−14=115−1100=851500u=−150085u=−17.64m

A man cannot see distinctly less than $15 c m$ and more than $100 c m$ . He uses a concave lens of focal length $- 100 c m$ to see the distant objects clearly. What will be his new near point?