Question

Which of the following optical phenomena is used in cinematography or movie projectors ?
(A) Accommodation
(B) Persistence of vision
(C) Long sightedness
(D) Short sightedness

Answer 1

Hint:In order to solve this problem we must know about the vision range of the human eye i.e., the human eye and brain can only process 10 to 12 separate images per second retaining an image for up to a sixteenth of a second.

Complete step by step answer:
We know that animation works by using an optical illusion. By presenting a sequence of still images in quick enough succession, the viewer interprets them as continuous moving images.
-Accommodation is the process in which the eyes see objects at different distances and maintain clear images of the objects by the convergence and divergence of light. Hence option A is not correct.
-This is the same principle that enables line action film making and projection to work. So, film theorists often refer to this illusion of movement as the persistence of vision. This optical phenomena is the persistence of vision. Hence, option B is the correct answer.
-Long sightedness means your long vision is clear while your near vision is blurry. Hence option C is not correct.
-Short sightedness means your near vision is clear while your long vision is blurry. Hence, option D is not correct.

Note:Here one point is noted that persistence of vision happens when the human brain perceives more than two images that are formed on the retina within a time period 1/16 th of a second. But many times students may confuse between short sightedness and long sightedness. So, students always remember the difference between them.