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?
Vhon​

Answer 1

dont know dear so sorry

Answer 2

Answer:

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,

⟹$\large{\frac{1}{f}}$=$\large{\frac{1}{v}}$-$\large{\frac{1}{u}}$

⟹$\large{\frac{1}{f}}$= $\large{\frac{1}{-75}}$-$\large{\frac{1}{infinity}}$

⟹f=−75cm

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