What is meant by persistence of vision ? Give one example from daily life.

Answer: The impression of an image remains on the retina for about 1/16th of a second after the object is removed; this is persistence of vision. Example: motion pictures (cinema).

Because the impression lasts for about 1/16 s, if separate pictures are shown to the eye at a rate faster than about 16 per second, the eye cannot see them separately and we see continuous motion. This is how a film is seen as a moving picture.

Other examples: the blades of a fast-rotating fan look like a disc; a burning incense stick moved quickly in a circle looks like a ring of light.