Question

my brother's question of class 8th. plz explain this line

Answer 1

It means if you are shown an image for lesser time than 1/16th of a second then your eyes won't recognize the object ...Means you won't be able to see it.To see it the object must be present for at least 1/16th of a second..

Answer 2

this means that an image will be persist on retina for 1/16th of seconds only after 1/16th seconds we can focus on any other image

eg Newton's disc.,we find white colour only when we rotate the disc (with 7 colours) faster