Question

a person with myopia can see objects placed at a distance of 4m.If he wants to see objects at a distance of 20m ,what should be the focal length and power of the concave lens he must wear. ​

Answer 1

Answer:

The distance of far point X=2m

To view distant object clearly, concave lens of focal length −2m should be used.

i.e. f=−X=−2m

Power of lens =P=

f

1

=

−2

1

=−0.5D