(C) The person wants to see an object placed at $u = -25\, cm$ as if it were at their near point $v = -50\, cm$.Using the lens formula: $\frac{1}{f} =

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Convex lens of focal length $50\, cm$

(C) The person wants to see an object placed at $u = -25\, cm$ as if it were at their near point $v = -50\, cm$.Using the lens formula: $\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$.Substituting the values: $\frac{1}{f} = \frac{1}{-50} - \frac{1}{-25}$.$\frac{1}{f} = -\frac{1}{50} + \frac{1}{25} = \frac{-1 + 2}{50} = \frac{1}{50}$.Thus,$f = +50\, cm$.$A$ positive focal length indicates a convex lens of focal length $50\, cm$.

Class 12 Physics Ray Optics and Optical Instruments Human Eye and Defects of Vision

Easy

$A$ person has a near point of $50\, cm$. What lens should they use to reduce it to $25\, cm$?

A
Concave lens of focal length $50\, cm$
B
Convex lens of focal length $25\, cm$
C
Convex lens of focal length $50\, cm$
D
Concave lens of focal length $25\, cm$

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Ray Optics and Optical Instruments

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Human Eye and Defects of Vision

Your friend is having an eyesight problem. She is not able to see a distant uniform window mesh clearly,and it appears to her as non-uniform and distorted. The doctor diagnosed the problem as:

MediumJEE MAIN 2021

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DifficultAIIMS 2019

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$A$ person uses a lens of power $+3 \text{ D}$ to normalize vision. The near point of the hypermetropic eye is ....... $m$.

Medium

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$A$ short-sighted person can see distinctly only those objects which lie between $10\, cm$ and $100\, cm$ from him. The power of the spectacle lens required to see a distant object is

Medium

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$A$ man with defective eyes cannot see objects distinctly at a distance of more than $60 \, cm$ from his eyes. The power of the lens to be used will be:

Medium

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$A$ person has a near point of $50\, cm$. What lens should they use to reduce it to $25\, cm$?

Similar Questions

Your friend is having an eyesight problem. She is not able to see a distant uniform window mesh clearly,and it appears to her as non-uniform and distorted. The doctor diagnosed the problem as:

$A$ person wears normal spectacles in which the distance between the glasses and the eyes is approximately $2 \, cm$. The power required is $-5 \, D$. If he wears contact lenses,then the required power is ......... $D$.

$A$ person uses a lens of power $+3 \text{ D}$ to normalize vision. The near point of the hypermetropic eye is ....... $m$.

$A$ short-sighted person can see distinctly only those objects which lie between $10\, cm$ and $100\, cm$ from him. The power of the spectacle lens required to see a distant object is

$A$ man with defective eyes cannot see objects distinctly at a distance of more than $60 \, cm$ from his eyes. The power of the lens to be used will be:

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