Consider the situation shown in fig. The two slits `S_(1)` and `S_(2)` placed symmetrically around the central line are illuminated by monochromatic light of wavelength `lambda`. The separation between the slit is d. The ligth transmitted by the slits falls on a screen `S_(0)` placed at a distance D form the slits. The slit `S_(3)` is at the central line and the slit `S_(4)` is at a distance z from `S_(3)` Another screen `S_(c)` is placed a further distance D away from `S_(c)` Find the ratio of the maximum to minimum intensity observed on `S_(c)`

If `z = (lambda D)/(4 d)`