Moving Pictures

The principle of persistence of vision is used in making movies (also known as motion pictures.) Movies and cartoons are made up of a series of separate pictures, flashed on the screen at a speed of 24 per second. When you’re watching a movie, each image lingers on the retina long enough to merge with the next image and you get the illusion of motion. You don’t even notice that the movie screen is dark half the time!

You can see this yourself with motion toys like flipbooks and thaumatropes.