PDF chapter test TRY NOW

Make a round mark and a cross on a sheet of paper with the spot to the right of the cross (Fig.). The distance between two marks may be 6-8 cm. Hold the sheet of paper at an arm’s length from the eye. Close your left eye. Look continuously at the cross. Move the sheet slowly towards you, keeping your eye on the cross. What do you find? Does the round mark disappear at some point? Now close your right eye. Look at the round mark now and repeat the activity. Does the cross disappear?
  
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Demonstration of blind spot
 
, the cross .
 
This shows that there  on the retina which cannot send messages to the brain when light falls on it.