Question

a person from bright sunlight outside enters a poorly lit room and feels blinded for a while

Answer 1

When a person from bright sunlight enters a poorly lit room he feels blinded for a short while, this phenomenon is known as light adaptation. It is a process of adjusting the diameter of pupil to low levels of illumination; cones cells meant for colours and fine details adapt first; rods works in dim light takes more time in order to adapt. In the bright light, cones pick up sharp images and colours. But once in low light, the cones become inoperative which leads to reduced vision. Slowly diameter size of pupil is adjusted and switch over between cones and rods takes place, which makes the light adaptation in the retina. 

Answer 2

Answer:

• The iris muscles contract and the pupils shrink when we are in bright light, allowing less light to enter the eye.
• The eyes need time to acclimatise and the iris muscles need time to dilate the pupils so that more light may reach the eye when we transition from bright light to a dark room.
• As a result, we experience blindness during the time when the eye muscles are attempting to adjust the eyes to the amount of light.
• Coming out of a dark room temporarily renders one blind. This is referred to as eye light adaption.
• It is caused by the pupil contracting to block light from entering the eye and the pigment rhodopsin being bleached to lessen the sensitivity of the rods.

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