Tag: physics

The eye lens is made up of a fibrous, jelly-like material. Its curvature can be modified to change its focal length to some extent by the ciliary muscles. When the muscles are relaxed, the curvature decreases making the lens thin and the focal length increases. Similarly when the ciliary muscles contract the curvature of the eye lens increases making them thicker, this decreases the focal length of the eye.

Images formed on retina of human eye are real and inverted by the convex nature of lens in eye. 

Persistence of Vision is used in cinematography or movie projectors. Persistence of vision works because the human eye and brain can only process 10 to 12 separate images per second, retaining an image for up to a sixteenth of a second. If a subsequent image replaces it in this period of time it will create the illusion of continuity. Animation works by using an optical illusion. By presenting a sequence of still images in quick enough succession, the viewer interprets them as a continuous moving image. This is the same principle that enables live action film making and projection to work. Film theorists often refer to this illusion of movement as the persistence of vision.

Retina is a part of human eye which act as a screen with photo receptor where image will be formed and signal will be sent to the brain.

The least distance of distinct vision for a normal eye is 25 cm.

Most of the refraction for the light rays entering the eye occurs at the outer surface of the cornea.

True

A. Iris is the muscular diaphragm in the human eye that controls the pupil.

In long sightedness eyes ball's size decrease or focal length of the lens increase due to which image will form behind in the retina.