Question

A person with a myopic eye cannot see object beyond -1.2m distinctly .the power of the corrective lens used to restore proper vision is​

Answer 1

Answer:

We will be using a concave lens of power -0.83 D.

Explanation:

We will calculate this using the lens formula.

Here, we will take object distance (u) to be ∞, as it is the far point of a human eye. We will take the image distance (v) as - 1.2 m, as it is the person's far point.

Lens Formula: 1/v - 1/u = 1/f        Here f is the focal length

                       -1/1.2 - 1/∞ = 1/f

                        1/f = -1/1.2            (Because 1/∞ = 0)

                           f = -1.2 m

Power of the lens = 1/f = -1/1.2 = -0.83 D

Hence we will be using a concave lens of power -0.83 D.

Also, always make sure that while calculating power, focal length is in meters.