Question

The near point a certain hyperopic eye is 100 cm in front of the eye. To see clearly an object that is 25 cm in front of the eye, what contact lens is required?

Answer 1

Explanation:

It is given that,

The near point a certain hyperopic eye is 100 cm in front of the eye, image distance, v = -100 cm

Object distance, u = -25 cm

We need to find the type of contact lens required. It can be claimed by finding the power of the lens. Let f is the focal length of the lens. It can be calculated using lens formula as :

$\dfrac{1}{f}=\dfrac{1}{v}-\dfrac{1}{u}$

$\dfrac{1}{f}=\dfrac{1}{-100}-\dfrac{1}{-25}$

$f=33.33\ cm$

As the focal length is positive, the convex lens of focal length +33.33 cm is required. Hence, this is the required solution.