Answer the following questions briefly :
Explain how the human eye adapts itself to bright light and dim light.

Explanation

When we move from a brightly lighted area to a dark room i.e., in dim light, we experience difficulty in seeing objects for some time. Slowly, our vision is improved. This is called dark adaptation. The pupil dilates to allow more light to enter the eyes and rhodopsin/ visual purple is generated. When we enter a brightly lighted area after being in a dimly lit area for a period of time, we experience a dazzling light for short period after which our vision improves. This is called the light adaptation. Pupil constricts to allow less light to enter our eyes and rhodopsin pigment is degenerate.