Name the defects of vision of the human eye.

The focal length of the eye lens increases when eye muscles

$A$ person with a myopic eye cannot see objects beyond $1.2\, m$ distinctly. What should be the type of the corrective lens used to restore proper vision?

$(a)$ State two main causes of a person developing near-sightedness (myopia). With the help of a ray diagram, suggest how this disability can be corrected.
$(b)$ The far point of a myopic person is $150 \ cm$ in front of the eye. Calculate the focal length and power of the lens required to enable him to see distant objects clearly.

$(a)$ Explain how a normal human eye is able to see distinctly objects placed at a distance as well as those placed at a nearer distance.
$(b)$ What are the far point and near point of a normal human eye?

Why does it take some time to see objects in a cinema hall when we just enter the hall from bright sunlight? Explain in brief.