Question

If a farsighted person has a near point that is 0.600 m from the eye, what is the focal length f2 of the contact lenses that the person would need to be able to read a book held at 0.350 m from the person's eyes?

Answer 1

Answer:

f = 0.84 m

Explanation:

given,

near point of the distance from eye(d_i) = 0.60 m

distance he can read (d_o)= 0.350 m

focal length of the contact lens = ?

now,

Using lens formula

$\dfrac{1}{f} = \dfrac{1}{d_0} + \dfrac{1}{d_i}$

$\dfrac{1}{f} = \dfrac{1}{0.35} + \dfrac{1}{-0.6}$

$\dfrac{1}{f} = 1.19$

$f = \dfrac{1}{1.19}$

f = 0.84 m

Hence, The focal length of the contact lens that person needed is equal to

f = 0.84 m