Question

If D is the distance of far point for a Myopic eye then what is the focal length of

concave lens required to rectify the deffect ​

Answer 1

Answer:

Explanation:

Given: the far point of a myopic person is 75 cm

To find: the focal length of the lens used to rectify this defect

Solution:

The person suffering from myopia should use a concave lens such that the image of an object at infinity is formed at a distance of 75 cm. i,e

u=∞

v=−75cm

Applying lens formula,

f

1

​  

=  

v

1

​  

−  

u

1

​  

 

⟹  

f

1

​  

=  

−75

1

​  

−  

∞

1

​  

 

⟹f=−75cm

is the required focal length of the lens to be used to rectify the defect.

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