Question

A zone plate differ from a convex lens because 1- it forms coloured images 2- it form real images 3- it form multiple images 4- it does not form images

Answer 1

    1. At infinity 
    2. Beyond 2F 
    3. At 2F 
    4. Between F and 2F 
    5. At the focus F 
    6. Between the focus F and optical centre C 

Answer 2

I think answer is 5