Question

why object are not seen clearly when we enter from bright light to room with dim light.

Answer 1

in bright light our pupil is so small
anf when we enter a dark room very less light comes in eyes so objects are not seen clearly in a dark room

Answer 2

the pupil adjusts its opening according to the amount of light it gets from the surrounding if the light is more then the pupil will contract to avoid more light similarly when light is less it opens widely to receive more light
so when we are in bright light and suddenly go to dark room the pupil initially will be contracted and in dim light the light available will also be less so less light will be available to eye and gradually the pupil start expanding and vision become clearer