Persistence of vision

Persistence of Vision

The image formed on the retina of the eye does not fade away instantaneously, when the object is removed from the sight. The impression (or sensation) of the object remains on the retina for about (1/16)th of a second, even afterthe object is removed from the sight. This continuance of the sensation of eye is called the persistence of vision.

Let a sequence of still pictures is taken by a movie camera. If the sequence of these still pictures is projected on a screen at a rate of 24 images or more per second then the successive impressions of the images on the screen appear to blend or merge smoothly into one another. This is because an image (or a scene) on the screen appears just before the impression of previous image on the retina is lost. Hence, the sequence of images blend into one another giving the impression of a moving picture. This principle is used in motion picture projection or in cinematography. NCERT solutions for class 8 Science prepared by Physics Wallah will help you to solve your NCERT text book exercise. 

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