Question

How are we able to see a moving picture?

Answer 1

Hint: The reason why we are able to see moving pictures is connected to the persistence of vision. An object will continue to persist in the eye for a very short duration even after the removal of that object.
The average time taken for an impression of an image to persist in the eye is $\dfrac{1}{{16}}$ of a second. Using this we can explain the reason why the picture appears to be moving.

Complete Step by step solution:
We are able to see a moving object due to the persistence of vision.
Persistence of vision is an ability of the human eye by virtue of which the image of an object continues to persist in the eye for a very short duration even after the removal of that object. The image of one object persists on the retina until an image of the next picture falls on the screen and so on in the case of moving pictures.
The average time taken for an impression of an image to persist in the eye is $\dfrac{1}{{16}}$ of a second. So, if a flash of still images at a rate faster than $16$per second falls on the screen, then the eye will perceive the object as a moving object. This principle is used in motion pictures.
The moving picture that we see is actually a compilation of several shots taken at different times. The shots of the picture are flashed at a rate greater than $16$ pictures per second which enable us to see the picture as moving.
Thus, persistence of vision is a phenomenon by which an illusion of motion is created. Brain is not able to process more than $16$ pictures per second. So, when stills are flashed at a rate higher than this. Brain interprets multiple images as one moving picture.

Note: Illusion of continuity is created due to inability of both eye and brain to process images at a rate faster than $16$ image per second. The exact time of persistence of an image also depends upon the brightness of an image.