Question

the far point of a myopic person is 80 cm in front of the eye. What is the nature and

the power of lens required to enable him to see very distant objects clearly?

Answer 1

For a person suffering from Myopia, a concave lens should be prescribed.

The power of the lens can be calculated using the lens formula

1/f = 1/v - 1/u

here

v = -80 cm

u = infinity

so,

1/f = 1/-80 - 1/∞

1/f = -1/80

or

f = -80 cm = -0.8m

the power of the lens would be

P =(1/-0.8) D

thus

P = -1.25 D