A hyperopic eye has a near point at 2 m A Determine the powe

A hyperopic eye has a near point at 2 m. A) Determine the power of the corrective lens for reading (book at 25 cm from the eyes). B) Assuming that the focal length for the reduced eye focused at its near point is 2.098 cm, estimate the size of the eyeball (distance to the retina).

Solution

A)

From thin lens equation

1/f = 1/p + 1/q

1/f = 1/0.25 + 1/-2

f=3.5 m

Power of the corrective lens is

P=1/f =1/3.5

P=0.2857 Diopters

b)

=>1/3.5 =1/p -1/0.02098

p=0.02085 m or 2.085 cm