Question

The far point of myopic person is 80m infront of the eye. What's the nature and power of the lens required to correct the problem????

Answer 1

We need to use the concave lens and the power of the lens should be 1.25 Dioptre.

Workout:

The person is suffering from myopia so, he need concave lens to correct his vision.
For this,
image distance,v=-80cm
object distance,u=infinitey
now by lens formula
1/v-1/u=1/f
1/-80-1/infinity=1/f
1/-80-0=1/f            ( 1/infinity=0)
1/-80=1/f
f=-80cm
=-0.8m
Now power=1/f
                   =1/-0.8
                   =-1.25D
therefore the power of concave lens required is -1.25D!
Hope u understand and helps u!!