Question

1) What is the far point and the near point of the human eye ?

2) A convex mirror of focal length $f$ produces an image ${ \binom{1}{n} }^{th}$of the size of the object. Calculate the distance of the object from the mirror .​

Answer 1

$\sf\small\underline\pink{Question:-}$

What is the far point and the near point of the human eye ?

$\sf\small\underline\pink{Answer:-}$

=> $\blue{\bold{Far\:Point}}$ : The farthest point up to which the eye can see objects cleanly is called the far point of the eye. It is infinity for the normal eye.

=> $\blue{\bold{Near\:Point}}$ : The nearest point up to which the eye can see an object clearly without any strain, is called the near point of the eye. It is at a distance of 25 cm from the eye.

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$\sf\small\underline\pink{Question:-}$

A convex mirror of focal length $f$ produces an image ${ \binom{1}{n} }^{th}$of the size of the object. Calculate the distance of the object from the mirror .

$\sf\small\underline\pink{Answer:-}$

⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀$m = \frac{v}{u} = \frac{1}{n}$

Therefore,⠀⠀⠀⠀⠀ ⠀⠀⠀$v = \frac{u}{n}$

We have,⠀⠀⠀⠀⠀⠀⠀$\frac{1}{v} + \frac{1}{u} = \frac{1}{f}$

Therefore,⠀⠀⠀⠀ ⠀⠀$\frac{n}{u} - \frac{1}{u} = \frac{1}{f}$

or

⠀⠀⠀⠀ ⠀⠀$[u = (n - 1)f]$

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