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? Express your answer in meters.

Answer 1

Answer:

f = 0.84 m

Explanation:

given,

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

focal length calculation = ?

distance he can read (d_o)= 0.350 m

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  

The focal length of the lens f = 0.84 m