Question

The distance of the eye-lens from the retina is x. For a normal eye, the maximum focal length of the eye-lens
(a) = x
(b) < x
(c) > x
(d) = 2 x

Answer 1

$\Large\underline{\underline{\sf \red{Given}:}}$

• Distance of eye lens from retina (v)= x

• Object is at infinity because , we have to find focal lenght (u) = ∞

$\Large\underline{\underline{\sf \red{To\:Find}:}}$

• Maximum focal lenght of eye lens (f) = ?

$\Large\underline{\underline{\sf \red{Solution}:}}$

Lens formula :-

$\large{\boxed{\sf \dfrac{1}{f}=\dfrac{1}{v}-\dfrac{1}{u} }}$

$\implies{\sf \dfrac{1}{f}=\dfrac{1}{v}-\dfrac{1}{∞} }$

$\implies{\sf \dfrac{1}{f}=\dfrac{1}{v}}$

$\implies{\sf f=v}$

$\implies{\sf f=x}$

$\Large\underline{\underline{\sf \red{Answer}:}}$

Option (a)= x

•°• For a normal eye, the maximum focal length of the eye-lens =x