Explain why, when it is getting dark at night, it is impossible to make out the color of cars on the road.

An object is moved closer to an eye. What changes must take place in the eye in order to keep the image in Sharp focus?

Why does the eye-lens not have to do all the work of converging incoming light rays?

Nocturnal animals (animals which sleep during the day and come out at night) tend to have wide pupils and lot of rods in their retinas. Suggest reasons for this.

Name one of the common defects of vision and the type of lens used to remove it.