Question

When we enter from bright sunlight to a dark room, we cannot see initially, why?

Answer 1

When we enter a darkened room from bright sunlight, we are unable to see at first. This is because the size of the pupil is small. When we enter the dark room, the pupil expands and more light enters the eye enabling us to see.

Answer 2

The eyes need to adjust pupil when it enters from the bright sunlight to dark room.

Explanation:

When the eyes are in bright light the pupil of the eyes shrinks in order to allow less light to enter the eyes.

But suddenly when we enter the dark room the pupil takes sometime to adjust to the darkness in the room.

The pupil needs to expand in order to see in the dark room. This is done so that the pupil can allow some light to enter the eyes.

This is the reason eyes cannot see anything suddenly when entering a dark room after bright sunlight.