Persistence of vision.
Human eyes work through chemical processes and cannot respond instantaneously to changes in light input. For this reason we still see things for a fraction of a second after they have actually changed.
This fact is exploited by movie projectors, TVs and computer monitors. Such systems project a successive sequence of still images at a very high rate - typically 48 (film - 24 frames shown twice per second), 50 or 60 (TV) or higher (computer monitors) times a second. This is so rapid that the human eye sees the resultant image as fairly flicker-free continuous motion.
Entry last updated 2002-01-16. Term 897 of 1487.
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